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URLhttps://github.com/casey/just
Last Crawled2026-04-02 09:16:32 (4 days ago)
First Indexed2016-07-14 16:09:52 (9 years ago)
HTTP Status Code200
Meta TitleGitHub - casey/just: šŸ¤– Just a command runner Ā· GitHub
Meta DescriptionšŸ¤– Just a command runner. Contribute to casey/just development by creating an account on GitHub.
Meta Canonicalnull
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Table of Contents ā†—ļø just is a handy way to save and run project-specific commands. This readme is also available as a book . The book reflects the latest release, whereas the readme on GitHub reflects latest master. (äø­ę–‡ę–‡ę”£åœØ čæ™é‡Œ , åæ«ēœ‹čæ‡ę„!) Commands, called recipes, are stored in a file called justfile with syntax inspired by make : You can then run them with just RECIPE : $ just test-all cc *.c -o main ./test --all Yay, all your tests passed! just has a ton of useful features, and many improvements over make : just is a command runner, not a build system, so it avoids much of make 's complexity and idiosyncrasies . No need for .PHONY recipes! Linux, MacOS, Windows, and other reasonable unices are supported with no additional dependencies. (Although if your system doesn't have an sh , you'll need to choose a different shell .) Errors are specific and informative, and syntax errors are reported along with their source context. Recipes can accept command line arguments . Wherever possible, errors are resolved statically. Unknown recipes and circular dependencies are reported before anything runs. just loads .env files , making it easy to populate environment variables. Recipes can be listed from the command line . Command line completion scripts are available for most popular shells . Recipes can be written in arbitrary languages , like Python or NodeJS. just can be invoked from any subdirectory, not just the directory that contains the justfile . And much more ! If you need help with just please feel free to open an issue or ping me on Discord . Feature requests and bug reports are always welcome! Installation Prerequisites just should run on any system with a reasonable sh , including Linux, MacOS, and the BSDs. Windows On Windows, just works with the sh provided by Git for Windows , GitHub Desktop , or Cygwin . After installation, sh must be available in the PATH of the shell you want to invoke just from. If you'd rather not install sh , you can use the shell setting to use the shell of your choice. Like PowerShell: # use PowerShell instead of sh: set shell := [ " powershell.exe" , " -c" ] hello : Write-Host " Hello, world!" ā€¦or cmd.exe : # use cmd.exe instead of sh: set shell := [ " cmd.exe" , " /c" ] list : dir You can also set the shell using command-line arguments. For example, to use PowerShell, launch just with --shell powershell.exe --shell-arg -c . (PowerShell is installed by default on Windows 7 SP1 and Windows Server 2008 R2 S1 and later, and cmd.exe is quite fiddly, so PowerShell is recommended for most Windows users.) Packages Cross-platform Package Manager Package Command arkade just arkade get just asdf just asdf plugin add just asdf install just <version> Cargo just cargo install just Cargo Binstall just cargo binstall just Conda just conda install -c conda-forge just Homebrew just brew install just Nix just nix-env -iA nixpkgs.just npm rust-just npm install -g rust-just pipx rust-just pipx install rust-just Snap just snap install --edge --classic just uv rust-just uv tool install rust-just BSD Operating System Package Manager Package Command FreeBSD pkg just pkg install just OpenBSD pkg_* just pkg_add just Linux Operating System Package Manager Package Command Alpine apk-tools just apk add just Arch pacman just pacman -S just Debian 13 and Ubuntu 24.04 derivatives apt just apt install just Fedora DNF just dnf install just Gentoo Portage dev-build/just emerge -av dev-build/just NixOS Nix just nix-env -iA nixos.just openSUSE Zypper just zypper in just Solus eopkg just eopkg install just Void XBPS just xbps-install -S just Windows Package Manager Package Command Chocolatey just choco install just Scoop just scoop install just Windows Package Manager Casey/Just winget install --id Casey.Just --exact macOS Package Manager Package Command MacPorts just port install just Pre-Built Binaries Pre-built binaries for Linux, MacOS, and Windows can be found on the releases page . You can use the following command on Linux, MacOS, or Windows to download the latest release, just replace DEST with the directory where you'd like to put just : curl --proto '=https' --tlsv1.2 -sSf https://just.systems/install.sh | bash -s -- --to DEST For example, to install just to ~/bin : # create ~ /bin mkdir -p ~/bin # download and extract just to ~ /bin/just curl --proto '=https' --tlsv1.2 -sSf https://just.systems/install.sh | bash -s -- --to ~/bin # add ` ~/bin ` to the paths that your shell searches for executables # this line should be added to your shells initialization file, # e.g. ` ~/.bashrc ` or ` ~/.zshrc ` export PATH="$PATH:$HOME/bin" # just should now be executable just --help Note that install.sh may fail on GitHub Actions, or in other environments where many machines share IP addresses. install.sh calls GitHub APIs in order to determine the latest version of just to install, and those API calls are rate-limited on a per-IP basis. To make install.sh more reliable in such circumstances, pass a specific tag to install with --tag . Another way to avoid rate-limiting is to pass a GitHub authentication token to install.sh as an environment variable named GITHUB_TOKEN , allowing it to authenticate its requests. Releases include a SHA256SUM file which can be used to verify the integrity of pre-built binary archives. To verify a release, download the pre-built binary archive along with the SHA256SUM file and run: shasum --algorithm 256 --ignore-missing --check SHA256SUMS GitHub Actions just can be installed on GitHub Actions in a few ways. Using package managers pre-installed on GitHub Actions runners on MacOS with brew install just , and on Windows with choco install just . With extractions/setup-just : - uses : extractions/setup-just@v3 with : just-version : 1.5.0 # optional semver specification, otherwise latest Or with taiki-e/install-action : - uses : taiki-e/install-action@just Docker just is available as a Docker image from the GitHub Container Registry . To copy just into a Docker image, add the following line to your Dockerfile : COPY --from=ghcr.io/casey/just:latest /just /usr/local/bin/ After copying, just may also be used as part of a docker build: RUN just Release RSS Feed An RSS feed of just releases is available here . Node.js Installation just-install can be used to automate installation of just in Node.js applications. just is a great, more robust alternative to npm scripts. If you want to include just in the dependencies of a Node.js application, just-install will install a local, platform-specific binary as part of the npm install command. This removes the need for every developer to install just independently using one of the processes mentioned above. After installation, the just command will work in npm scripts or with npx. It's great for teams who want to make the set up process for their project as easy as possible. For more information, see the just-install README file . Nix Flake The just repository includes a flake.nix that defines a nix flake , allowing you to use just as an input to another flake: { inputs = { just . url = "github:casey/just" ; } outputs = { self , nixpkgs , just } : { } } Backwards Compatibility With the release of version 1.0, just features a strong commitment to backwards compatibility and stability. Future releases will not introduce backwards incompatible changes that make existing justfile s stop working, or break working invocations of the command-line interface. This does not, however, preclude fixing outright bugs, even if doing so might break justfiles that rely on their behavior. There will never be a just 2.0. Any desirable backwards-incompatible changes will be opt-in on a per- justfile basis, so users may migrate at their leisure. Features that aren't yet ready for stabilization are marked as unstable and may be changed or removed at any time. Using unstable features produces an error by default, which can be suppressed by passing the --unstable flag, set unstable , or setting the environment variable JUST_UNSTABLE , to any value other than false , 0 , or the empty string. Editor Support justfile syntax is close enough to make that you may want to tell your editor to use make syntax highlighting for just . Vim and Neovim Vim version 9.1.1042 or better and Neovim version 0.11 or better support Justfile syntax highlighting out of the box, thanks to pbnj . vim-just The vim-just plugin provides syntax highlighting for justfile s. Install it with your favorite package manager, like Plug : call plug#begin () Plug ' NoahTheDuke/vim-just ' call plug#end () Or with Vim's built-in package support: mkdir -p ~/.vim/pack/vendor/start cd ~/.vim/pack/vendor/start git clone https://github.com/NoahTheDuke/vim-just.git tree-sitter-just tree-sitter-just is an Nvim Treesitter plugin for Neovim. Emacs just-mode provides syntax highlighting and automatic indentation of justfile s. It is available on MELPA as just-mode . justl provides commands for executing and listing recipes. You can add the following to an individual justfile to enable make mode on a per-file basis: # Local Variables: # mode: makefile # End: Visual Studio Code An extension for VS Code is available here . Unmaintained VS Code extensions include skellock/vscode-just and sclu1034/vscode-just . JetBrains IDEs A plugin for JetBrains IDEs by linux_china is available here . Kakoune Kakoune supports justfile syntax highlighting out of the box, thanks to TeddyDD. Helix Helix supports justfile syntax highlighting out-of-the-box since version 23.05. Sublime Text The Just package by nk9 with just syntax and some other tools is available on PackageControl . Micro Micro supports Justfile syntax highlighting out of the box, thanks to tomodachi94 . Zed The zed-just extension by jackTabsCode is available on the Zed extensions page . Other Editors Feel free to send me the commands necessary to get syntax highlighting working in your editor of choice so that I may include them here. Language Server Protocol just-lsp provides a language server protocol implementation, enabling features such as go-to-definition, inline diagnostics, and code completion. Model Context Protocol just-mcp provides a model context protocol adapter to allow LLMs to query the contents of justfiles and run recipes. Quick Start See the installation section for how to install just on your computer. Try running just --version to make sure that it's installed correctly. For an overview of the syntax, check out this cheatsheet . Once just is installed and working, create a file named justfile in the root of your project with the following contents: recipe-name : echo ' This is a recipe!' # this is a comment another-recipe : @ echo ' This is another recipe.' When you invoke just it looks for file justfile in the current directory and upwards, so you can invoke it from any subdirectory of your project. The search for a justfile is case insensitive, so any case, like Justfile , JUSTFILE , or JuStFiLe , will work. just will also look for files with the name .justfile , in case you'd like to hide a justfile . Running just with no arguments runs the first recipe in the justfile : $ just echo 'This is a recipe!' This is a recipe! One or more arguments specify the recipe(s) to run: $ just another-recipe This is another recipe. just prints each command to standard error before running it, which is why echo 'This is a recipe!' was printed. This is suppressed for lines starting with @ , which is why echo 'This is another recipe.' was not printed. Recipes stop running if a command fails. Here cargo publish will only run if cargo test succeeds: publish : cargo test # tests passed, time to publish! cargo publish Recipes can depend on other recipes. Here the test recipe depends on the build recipe, so build will run before test : build : cc main.c foo.c bar.c -o main test : build . / test sloc : @ echo " `wc -l *.c` lines of code" $ just test cc main.c foo.c bar.c -o main ./test testingā€¦ all tests passed! Recipes without dependencies will run in the order they're given on the command line: $ just build sloc cc main.c foo.c bar.c -o main 1337 lines of code Dependencies will always run first, even if they are passed after a recipe that depends on them: $ just test build cc main.c foo.c bar.c -o main ./test testingā€¦ all tests passed! Recipes may depend on recipes in submodules: mod foo baz : foo :: bar Examples A variety of justfile s can be found in the examples directory and on GitHub . Features The Default Recipe When just is invoked without a recipe, it runs the recipe with the [default] attribute, or the first recipe in the justfile if no recipe has the [default] attribute. This recipe might be the most frequently run command in the project, like running the tests: test : cargo test You can also use dependencies to run multiple recipes by default: default : lint build test build : echo Buildingā€¦ test : echo Testingā€¦ lint : echo Lintingā€¦ If no recipe makes sense as the default recipe, you can add a recipe to the beginning of your justfile that lists the available recipes: default : just --list Listing Available Recipes Recipes can be listed in alphabetical order with just --list : $ just --list Available recipes: build test deploy lint Recipes in submodules can be listed with just --list PATH , where PATH is a space- or :: -separated module path: $ cat justfile mod foo $ cat foo.just mod bar $ cat bar.just baz: $ just --list foo bar Available recipes: baz $ just --list foo::bar Available recipes: baz just --summary is more concise: $ just --summary build test deploy lint Pass --unsorted to print recipes in the order they appear in the justfile : test : echo ' Testing!' build : echo ' Building!' $ just --list --unsorted Available recipes: test build $ just --summary --unsorted test build If you'd like just to default to listing the recipes in the justfile , you can use this as your default recipe: default : @ just --list Note that you may need to add --justfile {{justfile()}} to the line above. Without it, if you executed just -f /some/distant/justfile -d . or just -f ./non-standard-justfile , the plain just --list inside the recipe would not necessarily use the file you provided. It would try to find a justfile in your current path, maybe even resulting in a No justfile found error. The heading text can be customized with --list-heading : $ just --list --list-heading $' Cool stuffā€¦ \n ' Cool stuffā€¦ test build And the indentation can be customized with --list-prefix : $ just --list --list-prefix Ā·Ā·Ā·Ā· Available recipes: Ā·Ā·Ā·Ā·test Ā·Ā·Ā·Ā·build The argument to --list-heading replaces both the heading and the newline following it, so it should contain a newline if non-empty. It works this way so you can suppress the heading line entirely by passing the empty string: $ just --list --list-heading ' ' test build Invoking Multiple Recipes Multiple recipes may be invoked on the command line at once: build : make web serve : python3 -m http.server -d out 8000 $ just build serve make web python3 -m http.server -d out 8000 Keep in mind that recipes with parameters will swallow arguments, even if they match the names of other recipes: build project : make {{ project }} serve : python3 -m http.server -d out 8000 $ just build serve make: *** No rule to make target `serve'. Stop. The --one flag can be used to restrict command-line invocations to a single recipe: $ just --one build serve error: Expected 1 command-line recipe invocation but found 2. Working Directory By default, recipes run with the working directory set to the directory that contains the justfile . The [no-cd] attribute can be used to make recipes run with the working directory set to directory in which just was invoked. @ foo : pwd [ no-cd ] @ bar : pwd $ cd subdir $ just foo / $ just bar /subdir You can override the working directory for all recipes with set working-directory := 'ā€¦' : set working-directory := ' bar' @ foo : pwd $ pwd /home/bob $ just foo /home/bob/bar You can override the working directory for a specific recipe with the working-directory attribute 1.38.0 : [ working-directory : ' bar' ] @ foo : pwd $ pwd /home/bob $ just foo /home/bob/bar The argument to the working-directory setting or working-directory attribute may be absolute or relative. If it is relative it is interpreted relative to the default working directory. Aliases Aliases allow recipes to be invoked on the command line with alternative names: alias b := build build : echo ' Building!' $ just b echo 'Building!' Building! The target of an alias may be a recipe in a submodule: mod foo alias baz := foo ::bar Settings Settings control interpretation and execution. Each setting may be specified at most once, anywhere in the justfile . For example: set shell := [ " zsh" , " -cu" ] foo : # this line will be run as `zsh -cu 'ls **/*.txt'` ls ** / *.txt Table of Settings Name Value Default Description allow-duplicate-recipes boolean false Allow recipes appearing later in a justfile to override earlier recipes with the same name. allow-duplicate-variables boolean false Allow variables appearing later in a justfile to override earlier variables with the same name. dotenv-filename string - Load a .env file with a custom name, if present. dotenv-load boolean false Load a .env file, if present. dotenv-override boolean false Override existing environment variables with values from the .env file. dotenv-path string - Load a .env file from a custom path and error if not present. Overrides dotenv-filename . dotenv-required boolean false Error if a .env file isn't found. export boolean false Export all variables as environment variables. fallback boolean false Search justfile in parent directory if the first recipe on the command line is not found. ignore-comments boolean false Ignore recipe lines beginning with # . lazy 1.47.0 boolean false Don't evaluate unused variables. positional-arguments boolean false Pass positional arguments. quiet boolean false Disable echoing recipe lines before executing. script-interpreter 1.33.0 [COMMAND, ARGSā€¦] ['sh', '-eu'] Set command used to invoke recipes with empty [script] attribute. shell [COMMAND, ARGSā€¦] - Set command used to invoke recipes and evaluate backticks. tempdir string - Create temporary directories in tempdir instead of the system default temporary directory. unstable 1.31.0 boolean false Enable unstable features. windows-powershell boolean false Use PowerShell on Windows as default shell. (Deprecated. Use windows-shell instead. windows-shell [COMMAND, ARGSā€¦] - Set the command used to invoke recipes and evaluate backticks. working-directory 1.33.0 string - Set the working directory for recipes and backticks, relative to the default working directory. Boolean settings can be written as: set NAME Which is equivalent to: set NAME := true Non-boolean settings can be set to both strings and expressions. 1.46.0 However, because settings affect the behavior of backticks and many functions, those expressions may not contain backticks or function calls, directly or transitively via reference. Allow Duplicate Recipes If allow-duplicate-recipes is set to true , defining multiple recipes with the same name is not an error and the last definition is used. Defaults to false . set allow-duplicate-recipes @ foo : echo foo @ foo : echo bar $ just foo bar Allow Duplicate Variables If allow-duplicate-variables is set to true , defining multiple variables with the same name is not an error and the last definition is used. Defaults to false . set allow-duplicate-variables a := " foo" a := " bar" @ foo : echo {{ a }} $ just foo bar Dotenv Settings If any of dotenv-load , dotenv-filename , dotenv-override , dotenv-path , or dotenv-required are set, just will try to load environment variables from a file. If dotenv-path is set, just will look for a file at the given path, which may be absolute, or relative to the working directory. The command-line option --dotenv-path , short form -E , can be used to set or override dotenv-path at runtime. If dotenv-filename is set just will look for a file at the given path, relative to the working directory and each of its ancestors. If dotenv-filename is not set, but dotenv-load or dotenv-required are set, just will look for a file named .env , relative to the working directory and each of its ancestors. dotenv-filename and dotenv-path are similar, but dotenv-path is only checked relative to the working directory, whereas dotenv-filename is checked relative to the working directory and each of its ancestors. It is not an error if an environment file is not found, unless dotenv-required is set. The loaded variables are environment variables, not just variables, and so must be accessed using $VARIABLE_NAME in recipes and backticks. If dotenv-override is set, variables from the environment file will override existing environment variables. For example, if your .env file contains: # a comment, will be ignored DATABASE_ADDRESS=localhost:6379 SERVER_PORT=1337 And your justfile contains: set dotenv-load serve : @ echo " Starting server with database $DATABASE_ADDRESS on port $SERVER_PORTā€¦" . / server --database $DATABASE_ADDRESS --port $SERVER_PORT just serve will output: $ just serve Starting server with database localhost:6379 on port 1337ā€¦ ./server --database $DATABASE_ADDRESS --port $SERVER_PORT Export The export setting causes all just variables to be exported as environment variables. Defaults to false . set export a := " hello" @ foo b : echo $a echo $b $ just foo goodbye hello goodbye Lazy The lazy setting 1.47.0 causes the evaluator to skip evaluating unused variables. This can be beneficial when a justfile contains variables that are expensive to evaluate but only sometimes used. In the following justfile , token will be skipped when only invoking bar : set lazy token := ` expensive-script-to-get-credentials ` foo : curl -H " Authorization: Bearer {{ token }} " https: // example.com / foo bar : cargo test Because just cannot determine when exported variables are used, assignments with export and assignments in a module with set export will always be evaluated. Positional Arguments If positional-arguments is true , recipe arguments will be passed as positional arguments to commands. For linewise recipes, argument $0 will be the name of the recipe. For example, running this recipe: set positional-arguments @ foo bar : echo $0 echo $ 1 Will produce the following output: $ just foo hello foo hello When using an sh -compatible shell, such as bash or zsh , $@ expands to the positional arguments given to the recipe, starting from one. When used within double quotes as "$@" , arguments including whitespace will be passed on as if they were double-quoted. That is, "$@" is equivalent to "$1" "$2" ā€¦ When there are no positional parameters, "$@" and $@ expand to nothing (i.e., they are removed). This example recipe will print arguments one by one on separate lines: set positional-arguments @ test * args = ' ' : bash -c ' while (( "$#" )); do echo - $1; shift; done' -- " $@" Running it with two arguments: $ just test foo " bar baz " - foo - bar baz Positional arguments may also be turned on a per-recipe basis with the [positional-arguments] attribute 1.29.0 : [ positional-arguments ] @ foo bar : echo $0 echo $ 1 Note that PowerShell does not handle positional arguments in the same way as other shells, so turning on positional arguments will likely break recipes that use PowerShell. If using PowerShell 7.4 or better, the -CommandWithArgs flag will make positional arguments work as expected: set shell := [ ' pwsh.exe' , ' -CommandWithArgs' ] set positional-arguments print-args a b c : Write-Output @($args[ 1. .($args.Count - 1 )]) Shell The shell setting controls the command used to invoke recipe lines and backticks. Shebang recipes are unaffected. The default shell is sh -cu . # use python3 to execute recipe lines and backticks set shell := [ " python3" , " -c" ] # use print to capture result of evaluation foos := ` print( " foo " * 4) ` foo : print( " Snake snake snake snake." ) print( " {{ foos }} " ) just passes the command to be executed as an argument. Many shells will need an additional flag, often -c , to make them evaluate the first argument. Windows Shell just uses sh on Windows by default. To use a different shell on Windows, use windows-shell : set windows-shell := [ " powershell.exe" , " -NoLogo" , " -Command" ] hello : Write-Host " Hello, world!" See powershell.just for a justfile that uses PowerShell on all platforms. Windows PowerShell set windows-powershell uses the legacy powershell.exe binary, and is no longer recommended. See the windows-shell setting above for a more flexible way to control which shell is used on Windows. just uses sh on Windows by default. To use powershell.exe instead, set windows-powershell to true. set windows-powershell := true hello : Write-Host " Hello, world!" Python 3 set shell := [ " python3" , " -c" ] Bash set shell := [ " bash" , " -uc" ] Z Shell set shell := [ " zsh" , " -uc" ] Fish set shell := [ " fish" , " -c" ] Nushell set shell := [ " nu" , " -c" ] If you want to change the default table mode to light : set shell := [ ' nu' , ' -m' , ' light' , ' -c' ] Nushell was written in Rust, and has cross-platform support for Windows / macOS and Linux . Documentation Comments Comments immediately preceding a recipe will appear in just --list : # build stuff build : . / bin / build # test stuff test : . / bin / test $ just --list Available recipes: build # build stuff test # test stuff The [doc] attribute can be used to set or suppress a recipe's doc comment: # This comment won't appear [ doc ( ' Build stuff' )] build : . / bin / build # This one won't either [ doc ] test : . / bin / test $ just --list Available recipes: build # Build stuff test Variables and Assignments Module-level variables may be created by assigning them a value with := : foo := " hello" bar := " world" baz : echo {{ foo + " " + bar }} All variables in a module may be printed: $ just --evaluate bar := "world" foo := "hello" Or the value of a single variable: $ just --evalaute foo hello All variables in a submodule or a single variable in a submodule may be printed with a path to the submodule or variable master : $ just --evaluate bob::bar x := "world" y := "hello" $ just --evaluate bob::bar::y hello The format of exported variables may be controlled with --evaluate-format master : $ just --evaluate --evaluate-format shell bar="world" foo="hello" The default format is --evaluate-format just : $ just --evaluate --evaluate-format just bar := "world" foo := "hello" Expressions and Substitutions Various operators and function calls are supported in expressions, which may be used in assignments, default recipe arguments, and inside recipe body {{ā€¦}} substitutions. tmpdir := ` mktemp -d ` version := " 0.2.7" tardir := tmpdir / " awesomesauce-" + version tarball := tardir + " .tar.gz" config := quote ( config_dir () / " .project-config" ) publish : rm -f {{ tarball }} mkdir {{ tardir }} cp README.md *.c {{ config }} {{ tardir }} tar zcvf {{ tarball }} {{ tardir }} scp {{ tarball }} me@server.com:release / rm -rf {{ tarball }} {{ tardir }} Concatenation The + operator returns the left-hand argument concatenated with the right-hand argument: foobar := ' foo' + ' bar' Logical Operators The logical operators && and || can be used to coalesce string values 1.37.0 , similar to Python's and and or . These operators consider the empty string '' to be false, and all other strings to be true. These operators are currently unstable. The && operator returns the empty string if the left-hand argument is the empty string, otherwise it returns the right-hand argument: foo := ' ' && ' goodbye' # '' bar := ' hello' && ' goodbye' # 'goodbye' The || operator returns the left-hand argument if it is non-empty, otherwise it returns the right-hand argument: foo := ' ' || ' goodbye' # 'goodbye' bar := ' hello' || ' goodbye' # 'hello' Joining Paths The / operator can be used to join two strings with a slash: foo := " a" / " b" $ just --evaluate foo a/b Note that a / is added even if one is already present: foo := " a/" bar := foo / " b" $ just --evaluate bar a//b Absolute paths can also be constructed 1.5.0 : foo := / " b" $ just --evaluate foo /b The / operator uses the / character, even on Windows. Thus, using the / operator should be avoided with paths that use universal naming convention (UNC), i.e., those that start with \? , since forward slashes are not supported with UNC paths. Escaping {{ To write a recipe containing {{ , use {{{{ : braces : echo ' I {{{{LOVE}} curly braces!' (An unmatched }} is ignored, so it doesn't need to be escaped.) Another option is to put all the text you'd like to escape inside of an interpolation: braces : echo '{{' I {{ LOVE }} curly braces! ' }}' Yet another option is to use {{ "{{" }} : braces : echo ' I {{ "{{" }} LOVE}} curly braces!' Strings 'single' , "double" , and '''triple''' quoted string literals are supported. Unlike in recipe bodies, {{ā€¦}} interpolations are not supported inside strings. Double-quoted strings support escape sequences: carriage-return := " \r " double-quote := " \" " newline := " \n " no-newline := " \ " slash := " \\ " tab := " \t " unicode-codepoint := " \u{1F916} " $ just --evaluate "arriage-return := " double-quote := """ newline := " " no-newline := "" slash := "\" tab := " " unicode-codepoint := "šŸ¤–" The unicode character escape sequence \u{ā€¦} 1.36.0 accepts up to six hex digits. Strings may contain line breaks: single := ' hello ' double := " goodbye " Single-quoted strings do not recognize escape sequences: escapes := ' \t\n\r\"\\' $ just --evaluate escapes := "\t\n\r\"\\" Indented versions of both single- and double-quoted strings, delimited by triple single- or double-quotes, are supported. Indented string lines are stripped of a leading line break, and leading whitespace common to all non-blank lines: # this string will evaluate to `foo\nbar\n` x := ''' foo bar ''' # this string will evaluate to `abc\n wuv\nxyz\n` y := """ abc wuv xyz """ Similar to unindented strings, indented double-quoted strings process escape sequences, and indented single-quoted strings ignore escape sequences. Escape sequence processing takes place after unindentation. The unindentation algorithm does not take escape-sequence produced whitespace or newlines into account. Shell-expanded strings Strings prefixed with x are shell expanded 1.27.0 : foobar := x ' ~/$FOO/${BAR}' Value Replacement $VAR value of environment variable VAR ${VAR} value of environment variable VAR ${VAR:-DEFAULT} value of environment variable VAR , or DEFAULT if VAR is not set Leading ~ path to current user's home directory Leading ~USER path to USER 's home directory This expansion is performed at compile time, so variables from .env files and exported just variables cannot be used. However, this allows shell expanded strings to be used in places like settings and import paths, which cannot depend on just variables and .env files. Format strings Strings prefixed with f are format strings 1.44.0 : name := " world" message := f ' Hello, {{ name }} !' Format strings may contain interpolations delimited with {{ā€¦}} that contain expressions. Format strings evaluate to the concatenated string fragments and evaluated expressions. Use {{{{ to include a literal {{ in a format string: foo := f ' I {{{{LOVE} curly braces!' Sigils Commands in linewise recipes may be prefixed with any combination of the sigils - , @ , and ? . The @ sigil toggles command echoing: foo : @ echo " This line won't be echoed!" echo " This line will be echoed!" @ bar : @ echo " This line will be echoed!" echo " This line won't be echoed!" The - sigil cause recipe execution to continue even if the command returns a nonzero exit status: # execution will continue, even if bar doesn't exist foo : - rmdir bar mkdir bar echo ' so much good stuff' > bar / stuff.txt The ? sigil 1.47.0 causes the current recipe to stop executing if the command exits with status code 1 , however execution of other recipes will continue. Exit status 0 causes the current recipe to continue execution as normal. All other exit codes are reserved and should not be used, as they may be given meaning in a future version of just . If the guards setting is unset or false, ? sigils are ignored and instead treated as part of the command. set guards @ foo : bar echo FOO @ bar : ?[[ -f baz ]] echo BAR $ just foo FOO $ touch baz $ just foo BAR FOO Functions just provides many built-in functions for use in expressions, including recipe body {{ā€¦}} substitutions, assignments, and default parameter values. All functions ending in _directory can be abbreviated to _dir . So home_directory() can also be written as home_dir() . In addition, invocation_directory_native() can be abbreviated to invocation_dir_native() . System Information arch() ā€” Instruction set architecture. Possible values are: "aarch64" , "arm" , "asmjs" , "hexagon" , "mips" , "msp430" , "powerpc" , "powerpc64" , "s390x" , "sparc" , "wasm32" , "x86" , "x86_64" , and "xcore" . num_cpus() 1.15.0 - Number of logical CPUs. os() ā€” Operating system. Possible values are: "android" , "bitrig" , "dragonfly" , "emscripten" , "freebsd" , "haiku" , "ios" , "linux" , "macos" , "netbsd" , "openbsd" , "solaris" , and "windows" . os_family() ā€” Operating system family; possible values are: "unix" and "windows" . For example: system-info : @ echo " This is an {{ arch () }} machine" . $ just system-info This is an x86_64 machine The os_family() function can be used to create cross-platform justfile s that work on various operating systems. For an example, see cross-platform.just file. External Commands shell(command, args...) 1.27.0 returns the standard output of shell script command with zero or more positional arguments args . The shell used to interpret command is the same shell that is used to evaluate recipe lines, and can be changed with set shell := [ā€¦] . command is passed as the first argument, so if the command is 'echo $@' , the full command line, with the default shell command sh -cu and args 'foo' and 'bar' will be: 'sh' '-cu' 'echo $@' 'echo $@' 'foo' 'bar' This is so that $@ works as expected, and $1 refers to the first argument. $@ does not include the first positional argument, which is expected to be the name of the program being run. # arguments can be variables or expressions file := ' /sys/class/power_supply/BAT0/status' bat0stat := shell ( ' cat $1' , file) # commands can be variables or expressions command := ' wc -l' output := shell (command + ' "$1"' , ' main.c' ) # arguments referenced by the shell command must be used empty := shell ( ' echo' , ' foo' ) full := shell ( ' echo $1' , ' foo' ) error := shell ( ' echo $1' ) # Using python as the shell. Since `python -c` sets `sys.argv[0]` to `'-c'`, # the first "real" positional argument will be `sys.argv[2]`. set shell := [ " python3" , " -c" ] olleh := shell ( ' import sys; print(sys.argv[2][::-1])' , ' hello' ) Environment Variables env(key) 1.15.0 ā€” Retrieves the environment variable with name key , aborting if it is not present. home_dir := env ( ' HOME' ) test : echo " {{ home_dir }} " $ just /home/user1 env(key, default) 1.15.0 ā€” Retrieves the environment variable with name key , returning default if it is not present. env_var(key) ā€” Deprecated alias for env(key) . env_var_or_default(key, default) ā€” Deprecated alias for env(key, default) . A default can be substituted for an empty environment variable value with the || operator, currently unstable: set unstable foo := env ( ' FOO' , ' ' ) || ' DEFAULT_VALUE' Executables require(name) 1.39.0 ā€” Search directories in the PATH environment variable for the executable name and return its full path, or halt with an error if no executable with name exists. bash := require ( " bash" ) @ test : echo " bash: ' {{ bash }} '" $ just bash: '/bin/bash' which(name) 1.39.0 ā€” Search directories in the PATH environment variable for the executable name and return its full path, or the empty string if no executable with name exists. Currently unstable. set unstable bosh := which ( " bosh" ) @ test : echo " bosh: ' {{ bosh }} '" $ just bosh: '' Invocation Information is_dependency() - Returns the string true if the current recipe is being run as a dependency of another recipe, rather than being run directly, otherwise returns the string false . Invocation Directory invocation_directory() - Retrieves the absolute path to the current directory when just was invoked, before just changed it (chdir'd) prior to executing commands. On Windows, invocation_directory() uses cygpath to convert the invocation directory to a Cygwin-compatible / -separated path. Use invocation_directory_native() to return the verbatim invocation directory on all platforms. For example, to call rustfmt on files just under the "current directory" (from the user/invoker's perspective), use the following rule: rustfmt : find {{ invocation_directory () }} -name \*.rs -exec rustfmt {} \; Alternatively, if your command needs to be run from the current directory, you could use (e.g.): build : cd {{ invocation_directory () }} ; . / some_script_that_needs_to_be_run_from_here invocation_directory_native() - Retrieves the absolute path to the current directory when just was invoked, before just changed it (chdir'd) prior to executing commands. Justfile and Justfile Directory justfile() - Retrieves the path of the current justfile . justfile_directory() - Retrieves the path of the parent directory of the current justfile . For example, to run a command relative to the location of the current justfile : script : {{ justfile_directory () }} / scripts / some_script Source and Source Directory source_file() 1.27.0 - Retrieves the path of the current source file. source_directory() 1.27.0 - Retrieves the path of the parent directory of the current source file. source_file() and source_directory() behave the same as justfile() and justfile_directory() in the root justfile , but will return the path and directory, respectively, of the current import or mod source file when called from within an import or submodule. Module and Module Directory module_file() - Retrieves the path of the current module file. module_directory() - Retrieves the path of the parent directory of the current module file. module_file() and module_directory() behave the same as justfile() and justfile_directory() in the root justfile , but will return the path and directory, respectively, of the current mod source file when called from within submodule. Just Executable just_executable() - Absolute path to the just executable. For example: executable : @ echo The executable is at: {{ just_executable () }} $ just The executable is at: /bin/just Just Process ID just_pid() - Process ID of the just executable. For example: pid : @ echo The process ID is: {{ just_pid () }} $ just The process ID is: 420 String Manipulation append(suffix, s) 1.27.0 Append suffix to whitespace-separated strings in s . append('/src', 'foo bar baz') ā†’ 'foo/src bar/src baz/src' prepend(prefix, s) 1.27.0 Prepend prefix to whitespace-separated strings in s . prepend('src/', 'foo bar baz') ā†’ 'src/foo src/bar src/baz' encode_uri_component(s) 1.27.0 - Percent-encode characters in s except [A-Za-z0-9_.!~*'()-] , matching the behavior of the JavaScript encodeURIComponent function . quote(s) - Replace all single quotes with '\'' and prepend and append single quotes to s . This is sufficient to escape special characters for many shells, including most Bourne shell descendants. replace(s, from, to) - Replace all occurrences of from in s with to . replace_regex(s, regex, replacement) - Replace all occurrences of regex in s with replacement . Regular expressions are provided by the Rust regex crate . See the syntax documentation for usage examples. Capture groups are supported. The replacement string uses Replacement string syntax . trim(s) - Remove leading and trailing whitespace from s . trim_end(s) - Remove trailing whitespace from s . trim_end_match(s, substring) - Remove suffix of s matching substring . trim_end_matches(s, substring) - Repeatedly remove suffixes of s matching substring . trim_start(s) - Remove leading whitespace from s . trim_start_match(s, substring) - Remove prefix of s matching substring . trim_start_matches(s, substring) - Repeatedly remove prefixes of s matching substring . Case Conversion capitalize(s) 1.7.0 - Convert first character of s to uppercase and the rest to lowercase. kebabcase(s) 1.7.0 - Convert s to kebab-case . lowercamelcase(s) 1.7.0 - Convert s to lowerCamelCase . lowercase(s) - Convert s to lowercase. shoutykebabcase(s) 1.7.0 - Convert s to SHOUTY-KEBAB-CASE . shoutysnakecase(s) 1.7.0 - Convert s to SHOUTY_SNAKE_CASE . snakecase(s) 1.7.0 - Convert s to snake_case . titlecase(s) 1.7.0 - Convert s to Title Case . uppercamelcase(s) 1.7.0 - Convert s to UpperCamelCase . uppercase(s) - Convert s to uppercase. Path Manipulation Fallible absolute_path(path) - Absolute path to relative path in the working directory. absolute_path("./bar.txt") in directory /foo is /foo/bar.txt . canonicalize(path) 1.24.0 - Canonicalize path by resolving symlinks and removing . , .. , and extra / s where possible. extension(path) - Extension of path . extension("/foo/bar.txt") is txt . file_name(path) - File name of path with any leading directory components removed. file_name("/foo/bar.txt") is bar.txt . file_stem(path) - File name of path without extension. file_stem("/foo/bar.txt") is bar . parent_directory(path) - Parent directory of path . parent_directory("/foo/bar.txt") is /foo . without_extension(path) - path without extension. without_extension("/foo/bar.txt") is /foo/bar . These functions can fail, for example if a path does not have an extension, which will halt execution. Infallible clean(path) - Simplify path by removing extra path separators, intermediate . components, and .. where possible. clean("foo//bar") is foo/bar , clean("foo/..") is . , clean("foo/./bar") is foo/bar . join(a, bā€¦) - This function uses / on Unix and \ on Windows, which can be lead to unwanted behavior. The / operator, e.g., a / b , which always uses / , should be considered as a replacement unless \ s are specifically desired on Windows. Join path a with path b . join("foo/bar", "baz") is foo/bar/baz . Accepts two or more arguments. Filesystem Access path_exists(path) - Returns the string true if the path points at an existing entity and the string false otherwise. Traverses symbolic links, and returns the string false if the path is inaccessible or points to a broken symlink. read(path) 1.39.0 - Returns the content of file at path as string. Error Reporting error(message) - Abort execution and report error message to user. UUID and Hash Generation blake3(string) 1.25.0 - Return BLAKE3 hash of string as hexadecimal string. blake3_file(path) 1.25.0 - Return BLAKE3 hash of file at path as hexadecimal string. sha256(string) - Return the SHA-256 hash of string as hexadecimal string. sha256_file(path) - Return SHA-256 hash of file at path as hexadecimal string. uuid() - Generate a random version 4 UUID. Random choose(n, alphabet) 1.27.0 - Generate a string of n randomly selected characters from alphabet , which may not contain repeated characters. For example, choose('64', HEX) will generate a random 64-character lowercase hex string. Datetime datetime(format) 1.30.0 - Return local time with format . datetime_utc(format) 1.30.0 - Return UTC time with format . The arguments to datetime and datetime_utc are strftime -style format strings, see the chrono library docs for details. Semantic Versions semver_matches(version, requirement) 1.16.0 - Check whether a semantic version , e.g., "0.1.0" matches a requirement , e.g., ">=0.1.0" , returning the string "true" if so and the string "false" otherwise. Style style(name) 1.37.0 - Return a named terminal display attribute escape sequence used by just . Unlike terminal display attribute escape sequence constants, which contain standard colors and styles, style(name) returns an escape sequence used by just itself, and can be used to make recipe output match just 's own output. Recognized values for name are 'command' , for echoed recipe lines, error , and warning . For example, to style an error message: scary : @ echo ' {{ style ( " error" ) }} OH NO {{ NORMAL }} ' User Directories These functions 1.23.0 return paths to user-specific directories for things like configuration, data, caches, executables, and the user's home directory. On Unix, these functions follow the XDG Base Directory Specification . On MacOS and Windows, these functions return the system-specified user-specific directories. For example, cache_directory() returns ~/Library/Caches on MacOS and {FOLDERID_LocalAppData} on Windows. See the dirs crate for more details. cache_directory() - The user-specific cache directory. config_directory() - The user-specific configuration directory. config_local_directory() - The local user-specific configuration directory. data_directory() - The user-specific data directory. data_local_directory() - The local user-specific data directory. executable_directory() - The user-specific executable directory. home_directory() - The user's home directory. If you would like to use XDG base directories on all platforms you can use the env(ā€¦) function with the appropriate environment variable and fallback, although note that the XDG specification requires ignoring non-absolute paths, so for full compatibility with spec-compliant applications, you would need to do: xdg_config_dir := if env ( ' XDG_CONFIG_HOME' , ' ' ) =~ ' ^/' { env ( ' XDG_CONFIG_HOME' ) } else { home_directory () / ' .config' } Constants A number of constants are predefined: Name Value Value on Windows HEX 1.27.0 "0123456789abcdef" HEXLOWER 1.27.0 "0123456789abcdef" HEXUPPER 1.27.0 "0123456789ABCDEF" PATH_SEP 1.41.0 "/" "\" PATH_VAR_SEP 1.41.0 ":" ";" CLEAR 1.37.0 "\ec" NORMAL 1.37.0 "\e[0m" BOLD 1.37.0 "\e[1m" ITALIC 1.37.0 "\e[3m" UNDERLINE 1.37.0 "\e[4m" INVERT 1.37.0 "\e[7m" HIDE 1.37.0 "\e[8m" STRIKETHROUGH 1.37.0 "\e[9m" BLACK 1.37.0 "\e[30m" RED 1.37.0 "\e[31m" GREEN 1.37.0 "\e[32m" YELLOW 1.37.0 "\e[33m" BLUE 1.37.0 "\e[34m" MAGENTA 1.37.0 "\e[35m" CYAN 1.37.0 "\e[36m" WHITE 1.37.0 "\e[37m" BG_BLACK 1.37.0 "\e[40m" BG_RED 1.37.0 "\e[41m" BG_GREEN 1.37.0 "\e[42m" BG_YELLOW 1.37.0 "\e[43m" BG_BLUE 1.37.0 "\e[44m" BG_MAGENTA 1.37.0 "\e[45m" BG_CYAN 1.37.0 "\e[46m" BG_WHITE 1.37.0 "\e[47m" @ foo : echo {{ HEX }} $ just foo 0123456789abcdef Constants starting with \e are ANSI escape sequences . CLEAR clears the screen, similar to the clear command. The rest are of the form \e[Nm , where N is an integer, and set terminal display attributes. Terminal display attribute escape sequences can be combined, for example text weight BOLD , text style STRIKETHROUGH , foreground color CYAN , and background color BG_BLUE . They should be followed by NORMAL , to reset the terminal back to normal. Escape sequences should be quoted, since [ is treated as a special character by some shells. @ foo : echo ' {{ BOLD + STRIKETHROUGH + CYAN + BG_BLUE }} Hi! {{ NORMAL }} ' Attributes Recipes, mod statements, and aliases may be annotated with attributes that change their behavior. Name Type Description [arg(ARG, help="HELP")] 1.46.0 recipe Print help string HELP for ARG in usage messages. [arg(ARG, long="LONG")] 1.46.0 recipe Require values of argument ARG to be passed as --LONG option. [arg(ARG, pattern="PATTERN")] 1.45.0 recipe Require values of argument ARG to match regular expression PATTERN . [arg(ARG, short="S")] 1.46.0 recipe Require values of argument ARG to be passed as short -S option. [arg(ARG, value="VALUE")] 1.46.0 recipe Makes option ARG a flag which does not take a value. [confirm(PROMPT)] 1.23.0 recipe Require confirmation prior to executing recipe with a custom prompt. [confirm] 1.17.0 recipe Require confirmation prior to executing recipe. [default] 1.43.0 recipe Use recipe as module's default recipe. [doc(DOC)] 1.27.0 module, recipe Set recipe or module's documentation comment to DOC . [dragonfly] 1.47.0 recipe Enable recipe on DragonFly BSD. [env(ENV_VAR, VALUE)] 1.47.0 recipe Set environment variables for recipe. [extension(EXT)] 1.32.0 recipe Set shebang recipe script's file extension to EXT . EXT should include a period if one is desired. [freebsd] 1.47.0 recipe Enable recipe on FreeBSD. [group(NAME)] 1.27.0 module, recipe Put recipe or module in group NAME . [linux] 1.8.0 recipe Enable recipe on Linux. [macos] 1.8.0 recipe Enable recipe on MacOS. [metadata(METADATA)] 1.42.0 recipe Attach METADATA to recipe. [netbsd] 1.47.0 recipe Enable recipe on NetBSD. [no-cd] 1.9.0 recipe Don't change directory before executing recipe. [no-exit-message] 1.7.0 recipe Don't print an error message if recipe fails. [no-quiet] 1.23.0 recipe Override globally quiet recipes and always echo out the recipe. [openbsd] 1.38.0 recipe Enable recipe on OpenBSD. [parallel] 1.42.0 recipe Run this recipe's dependencies in parallel. [positional-arguments] 1.29.0 recipe Turn on positional arguments for this recipe. [private] 1.10.0 alias, recipe Make recipe, alias, or variable private. See Private Recipes . [script(COMMAND)] 1.32.0 recipe Execute recipe as a script interpreted by COMMAND . See script recipes for more details. [script] 1.33.0 recipe Execute recipe as script. See script recipes for more details. [unix] 1.8.0 recipe Enable recipe on Unixes. (Includes MacOS). [windows] 1.8.0 recipe Enable recipe on Windows. [working-directory(PATH)] 1.38.0 recipe Set recipe working directory. PATH may be relative or absolute. If relative, it is interpreted relative to the default working directory. A recipe can have multiple attributes, either on multiple lines: [ no-cd ] [ private ] foo : echo " foo" Or separated by commas on a single line 1.14.0 : [ no-cd , private ] foo : echo " foo" Attributes with a single argument may be written with a colon: [ group : ' bar' ] foo : Enabling and Disabling Recipes The [linux] , [macos] , [unix] , and [windows] attributes 1.8.0 are configuration attributes. By default, recipes are always enabled. A recipe with one or more configuration attributes will only be enabled when one or more of those configurations is active. This can be used to write justfile s that behave differently depending on which operating system they run on. The run recipe in this justfile will compile and run main.c , using a different C compiler and using the correct output binary name for that compiler depending on the operating system: [ unix ] run : cc main.c . / a.out [ windows ] run : cl main.c main.exe Disabling Changing Directory just normally executes recipes with the current directory set to the directory that contains the justfile . This can be disabled using the [no-cd] attribute 1.9.0 . This can be used to create recipes which use paths relative to the invocation directory, or which operate on the current directory. For example, this commit recipe: [ no-cd ] commit file : git add {{ file }} git commit Can be used with paths that are relative to the current directory, because [no-cd] prevents just from changing the current directory when executing commit . Requiring Confirmation for Recipes just normally executes all recipes unless there is an error. The [confirm] attribute 1.17.0 allows recipes require confirmation in the terminal prior to running. This can be overridden by passing --yes to just , which will automatically confirm any recipes marked by this attribute. Recipes dependent on a recipe that requires confirmation will not be run if the relied upon recipe is not confirmed, as well as recipes passed after any recipe that requires confirmation. [ confirm ] delete-all : rm -rf * Custom Confirmation Prompt The default confirmation prompt can be overridden with [confirm(PROMPT)] 1.23.0 : [ confirm ( " Are you sure you want to delete everything?" )] delete-everything : rm -rf * Metadata Metadata in the form of lists of strings may be attached to recipes with the [metadata(METADATA)] attribute 1.42.0 : [ metadata ( " hello" , " goodbye" )] foo : Metadata can be read using just --dump --dump-format json . Groups Recipes and modules may be annotated with one or more group names: [ group ( ' lint' )] js-lint : echo ' Running JS linterā€¦' [ group ( ' rust recipes' )] [ group ( ' lint' )] rust-lint : echo ' Running Rust linterā€¦' [ group ( ' lint' )] cpp-lint : echo ' Running C++ linterā€¦' # not in any group email-everyone : echo ' Sending mass emailā€¦' Recipes are listed by group: $ just --list Available recipes: email-everyone # not in any group [lint] cpp-lint js-lint rust-lint [rust recipes] rust-lint just --list --unsorted prints recipes in their justfile order within each group: $ just --list --unsorted Available recipes: (no group) email-everyone # not in any group [lint] js-lint rust-lint cpp-lint [rust recipes] rust-lint Groups can be listed with --groups : $ just --groups Recipe groups: lint rust recipes Use just --groups --unsorted to print groups in their justfile order. Command Evaluation Using Backticks Backticks can be used to store the result of commands: localhost := ` dumpinterfaces | cut -d: -f2 | sed ' s/\/.*// ' | sed ' s/ //g ' ` serve : . / serve {{ localhost }} 8080 Indented backticks, delimited by three backticks, are de-indented in the same manner as indented strings: # This backtick evaluates the command `echo foo\necho bar\n`, which produces the value `foo\nbar\n`. stuff := ``` echo foo echo bar ``` See the Strings section for details on unindenting. Backticks may not start with #! . This syntax is reserved for a future upgrade. The shell(ā€¦) function provides a more general mechanism to invoke external commands, including the ability to execute the contents of a variable as a command, and to pass arguments to a command. Conditional Expressions if / else expressions evaluate different branches depending on if two expressions evaluate to the same value: foo := if " 2" == " 2" { " Good!" } else { " 1984" } bar : @ echo " {{ foo }} " $ just bar Good! It is also possible to test for inequality: foo := if " hello" != " goodbye" { " xyz" } else { " abc" } bar : @ echo {{ foo }} $ just bar xyz And match against regular expressions: foo := if " hello" =~ ' hel+o' { " match" } else { " mismatch" } bar : @ echo {{ foo }} $ just bar match Regular expressions are provided by the regex crate , whose syntax is documented on docs.rs . Since regular expressions commonly use backslash escape sequences, consider using single-quoted string literals, which will pass slashes to the regex parser unmolested. Conditional expressions short-circuit, which means they only evaluate one of their branches. This can be used to make sure that backtick expressions don't run when they shouldn't. foo := if env_var ( " RELEASE" ) == " true" { ` get-something-from-release-database ` } else { " dummy-value" } Conditionals can be used inside of recipes: bar foo : echo {{ if foo == " bar" { " hello" } else { " goodbye" } }} Multiple conditionals can be chained: foo := if " hello" == " goodbye" { " xyz" } else if " a" == " a" { " abc" } else { " 123" } bar : @ echo {{ foo }} $ just bar abc Stopping execution with error Execution can be halted with the error function. For example: foo := if " hello" == " goodbye" { " xyz" } else if " a" == " b" { " abc" } else { error ( " 123" ) } Which produce the following error when run: error: Call to function `error` failed: 123 | 16 | error("123") Setting Variables from the Command Line Variables can be overridden from the command line. os := " linux" test : build . / test --test {{ os }} build : . / build {{ os }} $ just ./build linux ./test --test linux Any number of arguments of the form NAME=VALUE can be passed before recipes: $ just os=plan9 ./build plan9 ./test --test plan9 Or you can use the --set flag: $ just --set os bsd ./build bsd ./test --test bsd Variables in submodules can be overridden using the :: -separated path to the variable. A variable named bar in a submodule named foo may be overridden with foo::bar=VALUE or --set foo::bar VALUE . Getting and Setting Environment Variables Exporting just Variables Assignments prefixed with the export keyword will be exported to recipes as environment variables: export RUST_BACKTRACE := " 1" test : # will print a stack trace if it crashes cargo test Parameters prefixed with a $ will be exported as environment variables: test $ RUST_BACKTRACE = " 1" : # will print a stack trace if it crashes cargo test You can also use the [env(NAME, VALUE)] attribute to export environment variables to a specific recipe: [ env ( " RUST_BACKTRACE" , " 1" )] test : # will print a stack trace if it crashes cargo test Exported variables and parameters are not exported to backticks in the same scope. export WORLD := " world" # This backtick will fail with "WORLD: unbound variable" BAR := ` echo hello $WORLD ` # Running `just a foo` will fail with "A: unbound variable" a $ A $ B = ` echo $A ` : echo $A $B When export is set, all just variables are exported as environment variables. Unexporting Environment Variables Environment variables can be unexported with the unexport keyword 1.29.0 : unexport FOO @ foo : echo $FOO $ export FOO=bar $ just foo sh: FOO: unbound variable Getting Environment Variables from the environment Environment variables from the environment are passed automatically to the recipes. print_home_folder : echo " HOME is: '${HOME}'" $ just HOME is '/home/myuser' Setting just Variables from Environment Variables Environment variables can be propagated to just variables using the env() function. See environment-variables . Recipe Parameters Recipes may have parameters. Here recipe build has a parameter called target : build target : @ echo ' Building {{ target }} ā€¦' cd {{ target }} && make To pass arguments on the command line, put them after the recipe name: $ just build my-awesome-project Building my-awesome-projectā€¦ cd my-awesome-project && make To pass arguments to a dependency, put the dependency in parentheses along with the arguments: default : ( build " main" ) build target : @ echo ' Building {{ target }} ā€¦' cd {{ target }} && make Variables can also be passed as arguments to dependencies: target := " main" _ build version : @ echo ' Building {{ version }} ā€¦' cd {{ version }} && make build : ( _build target) A command's arguments can be passed to dependency by putting the dependency in parentheses along with the arguments: build target : @ echo " Building {{ target }} ā€¦" push target : ( build target) @ echo ' Pushing {{ target }} ā€¦' Parameters may have default values: default := ' all' test target tests = default : @ echo ' Testing {{ target }} : {{ tests }} ā€¦' . / test --tests {{ tests }} {{ target }} Parameters with default values may be omitted: $ just test server Testing server:allā€¦ ./test --tests all server Or supplied: $ just test server unit Testing server:unitā€¦ ./test --tests unit server Default values may be arbitrary expressions, but expressions containing the + , && , || , or / operators must be parenthesized: arch := " wasm" test triple = ( arch + " -unknown-unknown" ) input = ( arch / " input.dat" ) : . / test {{ triple }} The last parameter of a recipe may be variadic, indicated with either a + or a * before the argument name: backup + FILES : scp {{ FILES }} me@server.com: Variadic parameters prefixed with + accept one or more arguments and expand to a string containing those arguments separated by spaces: $ just backup FAQ.md GRAMMAR.md scp FAQ.md GRAMMAR.md me@server.com: FAQ.md 100% 1831 1.8KB/s 00:00 GRAMMAR.md 100% 1666 1.6KB/s 00:00 Variadic parameters prefixed with * accept zero or more arguments and expand to a string containing those arguments separated by spaces, or an empty string if no arguments are present: commit MESSAGE * FLAGS : git commit {{ FLAGS }} -m " {{ MESSAGE }} " Variadic parameters can be assigned default values. These are overridden by arguments passed on the command line: test + FLAGS = ' -q' : cargo test {{ FLAGS }} {{ā€¦}} substitutions may need to be quoted if they contain spaces. For example, if you have the following recipe: search QUERY : lynx https: // www.google.com / ?q= {{ QUERY }} And you type: $ just search " cat toupee " just will run the command lynx https://www.google.com/?q=cat toupee , which will get parsed by sh as lynx , https://www.google.com/?q=cat , and toupee , and not the intended lynx and https://www.google.com/?q=cat toupee . You can fix this by adding quotes: search QUERY : lynx ' https://www.google.com/?q= {{ QUERY }} ' Parameters prefixed with a $ will be exported as environment variables: foo $ bar : echo $bar Parameters may be constrained to match regular expression patterns using the [arg("name", pattern="pattern")] attribute 1.45.0 : [ arg ( ' n' , pattern= ' \d+' )] double n : echo $(({{n}} * 2 )) A leading ^ and trailing $ are added to the pattern, so it must match the entire argument value. You may constrain the pattern to a number of alternatives using the | operator: [ arg ( ' flag' , pattern= ' --help|--version' )] info flag : just {{ flag }} Regular expressions are provided by the Rust regex crate . See the syntax documentation for usage examples. Usage information for a recipe may be printed with the --usage subcommand 1.46.0 : $ just --usage foo Usage: just foo [OPTIONS] bar Arguments: bar Help strings may be added to arguments using the [arg(ARG, help=HELP)] attribute: [ arg ( " bar" , help= " hello" )] foo bar : $ just --usage foo Usage: just foo bar Arguments: bar hello Recipe Flags and Options Recipe parameters are positional by default. In this justfile : @ foo bar : echo bar= {{ bar }} The parameter bar is positional: $ just foo hello bar=hello The [arg(ARG, long=OPTION)] 1.46.0 attribute can be used to make a parameter a long option. In this justfile : [ arg ( " bar" , long= " bar" )] foo bar : The parameter bar is given with the --bar option: $ just foo --bar hello bar=hello Options may also be passed with --name=value syntax: $ just foo --bar=hello bar=hello The value of long can be omitted, in which case the option defaults to the name of the parameter: [ arg ( " bar" , long)] foo bar : The [arg(ARG, short=OPTION)] 1.46.0 attribute can be used to make a parameter a short option. In this justfile : [ arg ( " bar" , short= " b" )] foo bar : The parameter bar is given with the -b option: $ just foo -b hello bar=hello If a parameter has both a long and short option, it may be passed using either. Variadic * and + parameters cannot be options. The [arg(ARG, value=VALUE, ā€¦)] 1.46.0 attribute can be used with long or short to make a parameter a flag which does not take a value. In this justfile : [ arg ( " bar" , long= " bar" , value= " hello" )] foo bar : The parameter bar is given with the --bar option, but does not take a value, and instead takes the value given in the [arg] attribute: $ just foo --bar bar=hello This is useful for unconditionally requiring a flag like --force on dangerous commands. A flag is optional if its parameter has a default: [ arg ( " bar" , long= " bar" , value= " hello" )] foo bar = " goodbye" : Causing it to receive the default when not passed in the invocation: $ just foo bar=goodbye Dependencies Dependencies run before recipes that depend on them: a : b @ echo A b : @ echo B $ just a B A In a given invocation of just , a recipe with the same arguments will only run once, regardless of how many times it appears in the command-line invocation, or how many times it appears as a dependency: a : @ echo A b : a @ echo B c : a @ echo C $ just a a a a a A $ just b c A B C Multiple recipes may depend on a recipe that performs some kind of setup, and when those recipes run, that setup will only be performed once: build : cc main.c test-foo : build . / a.out --test foo test-bar : build . / a.out --test bar $ just test-foo test-bar cc main.c ./a.out --test foo ./a.out --test bar Recipes in a given run are only skipped when they receive the same arguments: build : cc main.c test TEST : build . / a.out --test {{ TEST }} $ just test foo test bar cc main.c ./a.out --test foo ./a.out --test bar Running Recipes at the End of a Recipe Normal dependencies of a recipes always run before a recipe starts. That is to say, the dependee always runs before the depender. These dependencies are called "prior dependencies". A recipe can also have subsequent dependencies, which run immediately after the recipe and are introduced with an && : a : echo ' A!' b : a && c d echo ' B!' c : echo ' C!' d : echo ' D!' ā€¦running b prints: $ just b echo 'A!' A! echo 'B!' B! echo 'C!' C! echo 'D!' D! Running Recipes in the Middle of a Recipe just doesn't support running recipes in the middle of another recipe, but you can call just recursively in the middle of a recipe. Given the following justfile : a : echo ' A!' b : a echo ' B start!' just c echo ' B end!' c : echo ' C!' ā€¦running b prints: $ just b echo 'A!' A! echo 'B start!' B start! echo 'C!' C! echo 'B end!' B end! This has limitations, since recipe c is run with an entirely new invocation of just : Assignments will be recalculated, dependencies might run twice, and command line arguments will not be propagated to the child just process. Shebang Recipes Recipes that start with #! are called shebang recipes, and are executed by saving the recipe body to a file and running it. This lets you write recipes in different languages: polyglot : python js perl sh ruby nu python : #!/usr/bin/env python3 print( ' Hello from python!' ) js : #!/usr/bin/env node console.log( ' Greetings from JavaScript!' ) perl : #!/usr/bin/env perl print " Larry Wall says Hi! \n " ; sh : #!/usr/bin/env sh hello= ' Yo' echo " $hello from a shell script!" nu : #! / usr / bin / env nu let hello = ' Hola' echo $ " ($hello) from a nushell script!" ruby : #!/usr/bin/env ruby puts " Hello from ruby!" $ just polyglot Hello from python! Greetings from JavaScript! Larry Wall says Hi! Yo from a shell script! Hola from a nushell script! Hello from ruby! On Unix-like operating systems, including Linux and MacOS, shebang recipes are executed by saving the recipe body to a file in a temporary directory, marking the file as executable, and executing it. The OS then parses the shebang line into a command line and invokes it, including the path to the file. For example, if a recipe starts with #!/usr/bin/env bash , the final command that the OS runs will be something like /usr/bin/env bash /tmp/PATH_TO_SAVED_RECIPE_BODY . Shebang line splitting is operating system dependent. When passing a command with arguments, you may need to tell env to split them explicitly by using the -S flag: run : #!/usr/bin/env -S bash -x ls Windows does not support shebang lines. On Windows, just splits the shebang line into a command and arguments, saves the recipe body to a file, and invokes the split command and arguments, adding the path to the saved recipe body as the final argument. For example, on Windows, if a recipe starts with #! py , the final command the OS runs will be something like py C:\Temp\PATH_TO_SAVED_RECIPE_BODY . Script Recipes Recipes with a [script(COMMAND)] 1.32.0 attribute are run as scripts interpreted by COMMAND . This avoids some of the issues with shebang recipes, such as the use of cygpath on Windows, the need to use /usr/bin/env , inconsistencies in shebang line splitting across Unix OSs, and requiring a temporary directory from which files can be executed. Recipes with an empty [script] attribute are executed with the value of set script-interpreter := [ā€¦] 1.33.0 , defaulting to sh -eu , and not the value of set shell . The body of the recipe is evaluated, written to disk in the temporary directory, and run by passing its path as an argument to COMMAND . Script and Shebang Recipe Temporary Files Both script and shebang recipes write the recipe body to a temporary file for execution. Script recipes execute that file by passing it to a command, while shebang recipes execute the file directly. Shebang recipe execution will fail if the filesystem containing the temporary file is mounted with noexec or is otherwise non-executable. The directory that just writes temporary files to may be configured in a number of ways, from highest to lowest precedence: Globally with the --tempdir command-line option or the JUST_TEMPDIR environment variable 1.41.0 . On a per-module basis with the tempdir setting. Globally on Linux with the XDG_RUNTIME_DIR environment variable. Falling back to the directory returned by std::env::temp_dir . Python Recipes with uv uv is an excellent cross-platform python project manager, written in Rust. Using the [script] attribute and script-interpreter setting, just can easily be configured to run Python recipes with uv : set script-interpreter := [ ' uv' , ' run' , ' --script' ] [ script ] hello : print( " Hello from Python!" ) [ script ] goodbye : # /// script # requires-python = ">=3.11" # dependencies=["sh"] # /// import sh print(sh.echo( " Goodbye from Python!" ), end= ' ' ) Of course, a shebang also works: hello : #! / usr / bin / env -S uv run --script print( " Hello from Python!" ) Safer Bash Shebang Recipes If you're writing a bash shebang recipe, consider adding set -euxo pipefail : foo : #!/usr/bin/env bash set -euxo pipefail hello= ' Yo' echo " $hello from Bash!" It isn't strictly necessary, but set -euxo pipefail turns on a few useful features that make bash shebang recipes behave more like normal, linewise just recipe: set -e makes bash exit if a command fails. set -u makes bash exit if a variable is undefined. set -x makes bash print each script line before it's run. set -o pipefail makes bash exit if a command in a pipeline fails. This is bash -specific, so isn't turned on in normal linewise just recipes. Together, these avoid a lot of shell scripting gotchas. Shebang Recipe Execution on Windows On Windows, shebang interpreter paths containing a / are translated from Unix-style paths to Windows-style paths using cygpath , a utility that ships with Cygwin . For example, to execute this recipe on Windows: echo : #! / bin / sh echo " Hello!" The interpreter path /bin/sh will be translated to a Windows-style path using cygpath before being executed. If the interpreter path does not contain a / it will be executed without being translated. This is useful if cygpath is not available, or you wish to pass a Windows-style path to the interpreter. Setting Variables in a Recipe Recipe lines are interpreted by the shell, not just , so it's not possible to set just variables in the middle of a recipe: foo : x := " hello" # This doesn't work! echo {{ x }} It is possible to use shell variables, but there's another problem. Every recipe line is run by a new shell instance, so variables set in one line won't be set in the next: foo : x=hello && echo $x # This works! y=bye echo $y # This doesn't, `y` is undefined here! The best way to work around this is to use a shebang recipe. Shebang recipe bodies are extracted and run as scripts, so a single shell instance will run the whole thing: foo : #!/usr/bin/env bash set -euxo pipefail x=hello echo $x Sharing Environment Variables Between Recipes Each line of each recipe is executed by a fresh shell, so it is not possible to share environment variables between recipes. Using Python Virtual Environments Some tools, like Python's venv , require loading environment variables in order to work, making them challenging to use with just . As a workaround, you can execute the virtual environment binaries directly: venv : [ -d foo ] || python3 -m venv foo run : venv . / foo / bin / python3 main.py Changing the Working Directory in a Recipe Each recipe line is executed by a new shell, so if you change the working directory on one line, it won't have an effect on later lines: foo : pwd # This `pwd` will print the same directoryā€¦ cd bar pwd # ā€¦as this `pwd`! There are a couple ways around this. One is to call cd on the same line as the command you want to run: foo : cd bar && pwd The other is to use a shebang recipe. Shebang recipe bodies are extracted and run as scripts, so a single shell instance will run the whole thing, and thus a cd on one line will affect later lines, just like a shell script: foo : #!/usr/bin/env bash set -euxo pipefail cd bar pwd Indentation Recipe lines can be indented with spaces or tabs, but not a mix of both. All of a recipe's lines must have the same type of indentation, but different recipes in the same justfile may use different indentation. Each recipe must be indented at least one level from the recipe-name but after that may be further indented. Here's a justfile with a recipe indented with spaces, represented as Ā· , and tabs, represented as ā†’ . set windows-shell := [ " pwsh" , " -NoLogo" , " -NoProfileLoadTime" , " -Command" ] set ignore-comments list-space directory : Ā·Ā·#!pwsh Ā·Ā·foreach ($item in $(Get-ChildItem {{directory}} )) { Ā·Ā·Ā·Ā·echo $item.Name Ā·Ā·} Ā·Ā·echo " " # indentation nesting works even when newlines are escaped list-tab directory : ā†’ @foreach ($item in $(Get-ChildItem {{directory}} )) { \ ā†’ ā†’ echo $item.Name \ ā†’ } ā†’ @echo " " PS > just list - space ~ Desktop Documents Downloads PS > just list - tab ~ Desktop Documents Downloads Multi-Line Constructs Recipes without an initial shebang are evaluated and run line-by-line, which means that multi-line constructs probably won't do what you want. For example, with the following justfile : conditional : if true ; then echo ' True!' fi The extra leading whitespace before the second line of the conditional recipe will produce a parse error: $ just conditional error: Recipe line has extra leading whitespace | 3 | echo 'True!' | ^^^^^^^^^^^^^^^^ To work around this, you can write conditionals on one line, escape newlines with slashes, or add a shebang to your recipe. Some examples of multi-line constructs are provided for reference. if statements conditional : if true ; then echo ' True!' ; fi conditional : if true ; then \ echo ' True!' ; \ fi conditional : #!/usr/bin/env sh if true ; then echo ' True!' fi for loops for : for file in ` ls . ` ; do echo $file; done for : for file in ` ls . ` ; do \ echo $file; \ done for : #!/usr/bin/env sh for file in ` ls . ` ; do echo $file done while loops while : while ` server-is-dead ` ; do ping -c 1 server; done while : while ` server-is-dead ` ; do \ ping -c 1 server; \ done while : #!/usr/bin/env sh while ` server-is-dead ` ; do ping -c 1 server done Outside Recipe Bodies Parenthesized expressions can span multiple lines: abc := ( ' a' + ' b' + ' c' ) abc2 := ( ' a' + ' b' + ' c' ) foo param=( ' foo' + ' bar' ): echo {{ param }} bar : ( foo ' Foo' ) echo ' Bar!' Lines ending with a backslash continue on to the next line as if the lines were joined by whitespace 1.15.0 : a := ' foo' + \ ' bar' foo param1 \ param2= ' foo' \ *varparam= ' ' : dep1 \ (dep2 ' foo' ) echo {{ param1 }} {{ param2 }} {{ varparam }} dep1 : \ # this comment is not part of the recipe body echo ' dep1' dep2 \ param: echo ' Dependency with parameter {{ param }} ' Backslash line continuations can also be used in interpolations. The line following the backslash must be indented. recipe : echo ' {{ \ "This interpolation " + \ "has a lot of text." \ }}' echo ' back to recipe body' Command-line Options just supports a number of useful command-line options for listing, dumping, and debugging recipes and variables: $ just --list Available recipes: js perl polyglot python ruby $ just --show perl perl: #!/usr/bin/env perl print "Larry Wall says Hi!\n"; $ just --show polyglot polyglot: python js perl sh ruby Setting Command-line Options with Environment Variables Some command-line options can be set with environment variables For example, unstable features can be enabled either with the --unstable flag: $ just --unstable Or by setting the JUST_UNSTABLE environment variable: $ export JUST_UNSTABLE=1 $ just Since environment variables are inherited by child processes, command-line options set with environment variables are inherited by recursive invocations of just , where as command line options set with arguments are not. Consult just --help for which options can be set with environment variables. Private Recipes Recipes and aliases whose name starts with a _ are omitted from just --list : test : _test-helper . / bin / test _ test-helper : . / bin / super-secret-test-helper-stuff $ just --list Available recipes: test And from just --summary : $ just --summary test The [private] attribute 1.10.0 may also be used to hide recipes or aliases without needing to change the name: [ private ] foo : [ private ] alias b := bar bar : $ just --list Available recipes: bar This is useful for helper recipes which are only meant to be used as dependencies of other recipes. Quiet Recipes A recipe name may be prefixed with @ to invert the meaning of @ before each line: @ quiet : echo hello echo goodbye @ # all done! Now only the lines starting with @ will be echoed: $ just quiet hello goodbye # all done ! All recipes in a Justfile can be made quiet with set quiet : set quiet foo : echo " This is quiet" @ foo2 : echo " This is also quiet" The [no-quiet] attribute overrides this setting: set quiet foo : echo " This is quiet" [ no-quiet ] foo2 : echo " This is not quiet" Shebang recipes are quiet by default: foo : #!/usr/bin/env bash echo ' Foo!' $ just foo Foo! Adding @ to a shebang recipe name makes just print the recipe before executing it: @ bar : #!/usr/bin/env bash echo ' Bar!' $ just bar #!/usr/bin/env bash echo 'Bar!' Bar! just normally prints error messages when a recipe line fails. These error messages can be suppressed using the [no-exit-message] 1.7.0 attribute. You may find this especially useful with a recipe that wraps a tool: git * args : @ git {{ args }} $ just git status fatal: not a git repository (or any of the parent directories): .git error: Recipe `git` failed on line 2 with exit code 128 Add the attribute to suppress the exit error message when the tool exits with a non-zero code: [ no-exit-message ] git * args : @ git {{ args }} $ just git status fatal: not a git repository (or any of the parent directories): .git Selecting Recipes to Run With an Interactive Chooser The --choose subcommand makes just invoke a chooser to select which recipes to run. Choosers should read lines containing recipe names from standard input and print one or more of those names separated by spaces to standard output. Because there is currently no way to run a recipe that requires arguments with --choose , such recipes will not be given to the chooser. Private recipes and aliases are also skipped. The chooser can be overridden with the --chooser flag. If --chooser is not given, then just first checks if $JUST_CHOOSER is set. If it isn't, then the chooser defaults to fzf , a popular fuzzy finder. Arguments can be included in the chooser, i.e. fzf --exact . The chooser is invoked in the same way as recipe lines. For example, if the chooser is fzf , it will be invoked with sh -cu 'fzf' , and if the shell, or the shell arguments are overridden, the chooser invocation will respect those overrides. If you'd like just to default to selecting recipes with a chooser, you can use this as your default recipe: default : @ just -- choose Invoking justfile s in Other Directories If the first argument passed to just contains a / , then the following occurs: The argument is split at the last / . The part before the last / is treated as a directory. just will start its search for the justfile there, instead of in the current directory. The part after the last slash is treated as a normal argument, or ignored if it is empty. This may seem a little strange, but it's useful if you wish to run a command in a justfile that is in a subdirectory. For example, if you are in a directory which contains a subdirectory named foo , which contains a justfile with the recipe build , which is also the default recipe, the following are all equivalent: $ (cd foo && just build) $ just foo/build $ just foo/ Additional recipes after the first are sought in the same justfile . For example, the following are both equivalent: $ just foo/a b $ (cd foo && just a b) And will both invoke recipes a and b in foo/justfile . Imports One justfile can include the contents of another using import statements. If you have the following justfile : import ' foo/bar.just' a : b @ echo A And the following text in foo/bar.just : b : @ echo B foo/bar.just will be included in justfile and recipe b will be defined: $ just b B $ just a B A The import path can be absolute or relative to the location of the justfile containing it. A leading ~/ in the import path is replaced with the current users home directory. Justfiles are insensitive to order, so included files can reference variables and recipes defined after the import statement. Imported files can themselves contain import s, which are processed recursively. allow-duplicate-recipes and allow-duplicate-variables allow duplicate recipes and variables, respectively, to override each other, instead of producing an error. Within a module, later definitions override earlier definitions: set allow-duplicate-recipes foo : foo : echo ' yes' When import s are involved, things unfortunately get much more complicated and hard to explain. Shallower definitions always override deeper definitions, so recipes at the top level will override recipes in imports, and recipes in an import will override recipes in an import which itself imports those recipes. When two duplicate definitions are imported and are at the same depth, the one from the earlier import will override the one from the later import. This is because just uses a stack when processing imports, pushing imports onto the stack in source-order, and always processing the top of the stack next, so earlier imports are actually handled later by the compiler. This is definitely a bug, but since just has very strong backwards compatibility guarantees and we take enormous pains not to break anyone's justfile , we have created issue #2540 to discuss whether or not we can actually fix it. Imports may be made optional by putting a ? after the import keyword: import ? ' foo/bar.just' Importing the same source file multiple times is not an error 1.37.0 . This allows importing multiple justfiles, for example foo.just and bar.just , which both import a third justfile containing shared recipes, for example baz.just , without the duplicate import of baz.just being an error: # justfile import ' foo.just' import ' bar.just' # foo.just import ' baz.just' foo : baz # bar.just import ' baz.just' bar : baz # baz baz : Modules A justfile can declare modules using mod statements 1.19.0 . mod statements were stabilized in just 1.31.0 . If you have the following justfile : mod bar a : @ echo A And the following text in bar.just : b : @ echo B bar.just will be included in justfile as a submodule. Recipes, aliases, and variables defined in one submodule cannot be used in another, and each module uses its own settings. Recipes in submodules can be invoked as subcommands: $ just bar b B Or with path syntax: $ just bar::b B If a module is named foo , just will search for the module file in foo.just , foo/mod.just , foo/justfile , and foo/.justfile . In the latter two cases, the module file may have any capitalization. Module statements may be of the form: mod foo ' PATH' Which loads the module's source file from PATH , instead of from the usual locations. A leading ~/ in PATH is replaced with the current user's home directory. PATH may point to the module source file itself, or to a directory containing the module source file with the name mod.just , justfile , or .justfile . In the latter two cases, the module file may have any capitalization. Environment files are only loaded for the root justfile, and loaded environment variables are available in submodules. Settings in submodules that affect environment file loading are ignored. Recipes in submodules without the [no-cd] attribute run with the working directory set to the directory containing the submodule source file. justfile() and justfile_directory() always return the path to the root justfile and the directory that contains it, even when called from submodule recipes. Modules may be made optional by putting a ? after the mod keyword: mod ? foo Missing source files for optional modules do not produce an error. Optional modules with no source file do not conflict, so you can have multiple mod statements with the same name, but with different source file paths, as long as at most one source file exists: mod ? foo ' bar.just' mod ? foo ' baz.just' Modules may be given doc comments which appear in --list output 1.30.0 : # foo is a great module! mod foo $ just --list Available recipes: foo ... # foo is a great module! Modules are still missing a lot of features, for example, the ability to refer to variables in other modules. See the module improvement tracking issue for more information. Hiding justfile s just looks for justfile s named justfile and .justfile , which can be used to keep a justfile hidden. Just Scripts By adding a shebang line to the top of a justfile and making it executable, just can be used as an interpreter for scripts: $ cat > script << EOF #!/usr/bin/env just --justfile foo: echo foo EOF $ chmod +x script $ ./script foo echo foo foo When a script with a shebang is executed, the system supplies the path to the script as an argument to the command in the shebang. So, with a shebang of #!/usr/bin/env just --justfile , the command will be /usr/bin/env just --justfile PATH_TO_SCRIPT . With the above shebang, just will change its working directory to the location of the script. If you'd rather leave the working directory unchanged, use #!/usr/bin/env just --working-directory . --justfile . Note: Shebang line splitting is not consistent across operating systems. The previous examples have only been tested on macOS. On Linux, you may need to pass the -S flag to env : #! / usr / bin / env -S just -- justfile default : echo foo Formatting and dumping justfile s Each justfile has a canonical formatting with respect to whitespace and newlines. You can overwrite the current justfile with a canonically-formatted version using the currently-unstable --fmt flag: $ cat justfile # A lot of blank lines some-recipe: echo "foo" $ just --fmt --unstable $ cat justfile # A lot of blank lines some-recipe: echo "foo" Invoking just --fmt --check --unstable runs --fmt in check mode. Instead of overwriting the justfile , just will exit with an exit code of 0 if it is formatted correctly, and will exit with 1 and print a diff if it is not. You can use the --dump command to output a formatted version of the justfile to stdout: $ just --dump > formatted-justfile The --dump command can be used with --dump-format json to print a JSON representation of a justfile . Fallback to parent justfile s If a recipe is not found in a justfile and the fallback setting is set, just will look for justfile s in the parent directory and up, until it reaches the root directory. just will stop after it reaches a justfile in which the fallback setting is false or unset. As an example, suppose the current directory contains this justfile : set fallback foo : echo foo And the parent directory contains this justfile : bar : echo bar $ just bar Trying ../justfile echo bar bar Avoiding Argument Splitting Given this justfile : foo argument : touch {{ argument }} The following command will create two files, some and argument.txt : $ just foo " some argument.txt " The user's shell will parse "some argument.txt" as a single argument, but when just replaces touch {{argument}} with touch some argument.txt , the quotes are not preserved, and touch will receive two arguments. There are a few ways to avoid this: quoting, positional arguments, and exported arguments. Quoting Quotes can be added around the {{argument}} interpolation: foo argument : touch ' {{ argument }} ' This preserves just 's ability to catch variable name typos before running, for example if you were to write {{argument}} , but will not do what you want if the value of argument contains single quotes. Positional Arguments The positional-arguments setting causes all arguments to be passed as positional arguments, allowing them to be accessed with $1 , $2 , ā€¦, and $@ , which can be then double-quoted to avoid further splitting by the shell: set positional-arguments foo argument : touch " $1" This defeats just 's ability to catch typos, for example if you type $2 instead of $1 , but works for all possible values of argument , including those with double quotes. Exported Arguments All arguments are exported when the export setting is set: set export foo argument : touch " $argument" Or individual arguments may be exported by prefixing them with $ : foo $ argument : touch " $argument" This defeats just 's ability to catch typos, for example if you type $argument , but works for all possible values of argument , including those with double quotes. Configuring the Shell There are a number of ways to configure the shell for linewise recipes, which are the default when a recipe does not start with a #! shebang. Their precedence, from highest to lowest, is: The --shell and --shell-arg command line options. Passing either of these will cause just to ignore any settings in the current justfile. set windows-shell := [...] set windows-powershell (deprecated) set shell := [...] Since set windows-shell has higher precedence than set shell , you can use set windows-shell to pick a shell on Windows, and set shell to pick a shell for all other platforms. Timestamps just can print timestamps before each recipe commands: recipe : echo one sleep 2 echo two $ just --timestamp recipe [07:28:46] echo one one [07:28:46] sleep 2 [07:28:48] echo two two By default, timestamps are formatted as HH:MM:SS . The format can be changed with --timestamp-format : $ just --timestamp recipe --timestamp-format '%H:%M:%S%.3f %Z' [07:32:11:.349 UTC] echo one one [07:32:11:.350 UTC] sleep 2 [07:32:13:.352 UTC] echo two two The argument to --timestamp-format is a strftime -style format string, see the chrono library docs for details. Signal Handling Signals are messages sent to running programs to trigger specific behavior. For example, SIGINT is sent to all processes in the terminal foreground process group when CTRL-C is pressed. just tries to exit when requested by a signal, but it also tries to avoid leaving behind running child processes, two goals which are somewhat in conflict. If just exits leaving behind child processes, the user will have no recourse but to ps aux | grep for the children and manually kill them, a tedious endeavor. Fatal Signals SIGHUP , SIGINT , and SIGQUIT are generated when the user closes the terminal, types ctrl-c , or types ctrl-\ , respectively, and are sent to all processes in the foreground process group. SIGTERM is the default signal sent by the kill command, and is delivered only to its intended victim. When a child process is not running, just will exit immediately on receipt of any of the above signals. When a child process is running, just will wait until it terminates, to avoid leaving it behind. Additionally, on receipt of SIGTERM , just will forward SIGTERM to any running children 1.41.0 , since unlike other fatal signals, SIGTERM , was likely sent to just alone. Regardless of whether a child process terminates successfully after just receives a fatal signal, just halts execution. SIGINFO SIGINFO is sent to all processes in the foreground process group when the user types ctrl-t on BSD -derived operating systems, including MacOS, but not Linux. just responds by printing a list of all child process IDs and commands 1.41.0 . Windows On Windows, just behaves as if it had received SIGINT when the user types ctrl-c . Other signals are unsupported. Changelog A changelog for the latest release is available in CHANGELOG.md . Changelogs for previous releases are available on the releases page . just --changelog can also be used to make a just binary print its changelog. Miscellanea Re-running recipes when files change watchexec can re-run any command when files change. To re-run the recipe foo when any file changes: watchexec just foo See watchexec --help for more info, including how to specify which files should be watched for changes. Parallelism Dependencies may be run in parallel with the [parallel] attribute. In this justfile , foo , bar , and baz will execute in parallel when main is run: [ parallel ] main : foo bar baz foo : sleep 1 bar : sleep 1 baz : sleep 1 GNU parallel may be used to run recipe lines concurrently: parallel : #! / usr / bin / env -S parallel --shebang --ungroup --jobs {{ num_cpus () }} echo task 1 start; sleep 3 ; echo task 1 done echo task 2 start; sleep 3 ; echo task 2 done echo task 3 start; sleep 3 ; echo task 3 done echo task 4 start; sleep 3 ; echo task 4 done Shell Alias For lightning-fast command running, put alias j=just in your shell's configuration file. Shell Completion Scripts Shell completion scripts for Bash, Elvish, Fish, Nushell, PowerShell, and Zsh are available in release archives . The just binary can also generate the same completion scripts at runtime using just --completions SHELL : $ just --completions bash > just Bash The recommended approach is to use the bash-completions package to lazy-load the completion script: mkdir -p ~ /.local/share/bash-completion/completions just --completions bash > ~ /.local/share/bash-completion/completions/just If bash-completions is not installed, you can source the completion script in your .bashrc : source <( just --completions bash ) If you use an alias like alias j=just , you should also save the completion script with the name j when lazy-loading: just --completions bash > ~ /.local/share/bash-completion/completions/j Or if not lazy-loading, add this line after sourcing the completion script in your .bashrc : complete -F _clap_complete_just -o bashdefault -o default j Elvish In your rc.elv : set edit:completion:arg-completer [ just ] = { | @args | eval ( just --completions elvish | slurp ) set @result = ( edit:completion:arg-completer [ just ] $ @args ) put $ @result } Fish Save the completion script to the completions directory to lazy-load it: mkdir -p ~/.config/fish/completions just --completions fish > ~/.config/fish/completions/just.fish Nushell First save the completion script: just -- completions nushell | save - f ( $nu . default - config - dir | path join just . nu) Then in config.nu : source just . nu PowerShell In your PowerShell $PROFILE : just -- completions powershell | Out-String | Invoke-Expression Zsh First save the completion script: mkdir -p ~ /.zsh/completions just --completions zsh > ~ /.zsh/completions/_just Then in your .zshrc : fpath=(~/.zsh/completions $fpath ) autoload -U compinit compinit Man Page just can print its own man page with just --man . Man pages are written in roff , a venerable markup language and one of the first practical applications of Unix. If you have groff installed you can view the man page with just --man | groff -mandoc -Tascii | less . Grammar A non-normative grammar of justfile s can be found in GRAMMAR.md . just.sh Before just was a fancy Rust program it was a tiny shell script that called make . You can find the old version in contrib/just.sh . Global and User justfile s If you want some recipes to be available everywhere, you have a few options. Global Justfile just --global-justfile , or just -g for short, searches the following paths, in-order, for a justfile: $XDG_CONFIG_HOME/just/justfile $HOME/.config/just/justfile $HOME/justfile $HOME/.justfile You can put recipes that are used across many projects in a global justfile to easily invoke them from any directory. User justfile tips You can also adopt some of the following workflows. These tips assume you've created a justfile at ~/.user.justfile , but you can put this justfile at any convenient path on your system. Recipe Aliases If you want to call the recipes in ~/.user.justfile by name, and don't mind creating an alias for every recipe, add the following to your shell's initialization script: for recipe in `just --justfile ~/.user.justfile --summary`; do alias $recipe="just --justfile ~/.user.justfile --working-directory . $recipe" done Now, if you have a recipe called foo in ~/.user.justfile , you can just type foo at the command line to run it. It took me way too long to realize that you could create recipe aliases like this. Notwithstanding my tardiness, I am very pleased to bring you this major advance in justfile technology. Forwarding Alias If you'd rather not create aliases for every recipe, you can create a single alias: alias .j='just --justfile ~/.user.justfile --working-directory .' Now, if you have a recipe called foo in ~/.user.justfile , you can just type .j foo at the command line to run it. I'm pretty sure that nobody actually uses this feature, but it's there. ĀÆ\_(惄)_/ĀÆ Customization You can customize the above aliases with additional options. For example, if you'd prefer to have the recipes in your justfile run in your home directory, instead of the current directory: alias .j='just --justfile ~/.user.justfile --working-directory ~' Node.js package.json Script Compatibility The following export statement gives just recipes access to local Node module binaries, and makes just recipe commands behave more like script entries in Node.js package.json files: export PATH := " ./node_modules/.bin:" + env_var ( ' PATH' ) Paths on Windows On Windows, all functions that return paths, except invocation_directory() will return \ -separated paths. When not using PowerShell or cmd.exe these paths should be quoted to prevent the \ s from being interpreted as character escapes: ls : echo ' {{ absolute_path ( " ." ) }} ' cygpath.exe is an executable included in some distributions of Unix userlands for Windows, including Cygwin and Git for Windows. just uses cygpath.exe in two places: For backwards compatibility, invocation_directory() , uses cygpath.exe to convert the invocation directory into a unix-style / -separated path. Use invocation_directory_native() to get the native, Windows-style path. On unix, invocation_directory() and invocation_directory_native() both return the same unix-style path. cygpath.exe is used also used to convert Unix-style shebang lines into Windows paths. As an alternative, the [script] attribute can be used, which does not depend on cygpath.exe . If cygpath.exe is available, you can use it to convert between path styles: foo_unix := ' /hello/world' foo_windows := shell ( ' cygpath --windows $1' , foo_unix) bar_windows := ' C:\hello\world' bar_unix := shell ( ' cygpath --unix $1' , bar_windows) Remote Justfiles If you wish to include a mod or import source file in many justfiles without needing to duplicate it, you can use an optional mod or import , along with a recipe to fetch the module source: import ? ' foo.just' fetch : curl https: // raw.githubusercontent.com / casey / just / master / justfile > foo.just Given the above justfile , after running just fetch , the recipes in foo.just will be available. Printing Complex Strings echo can be used to print strings, but because it processes escape sequences, like \n , and different implementations of echo recognize different escape sequences, using printf is often a better choice. printf takes a C-style format string and any number of arguments, which are interpolated into the format string. This can be combined with indented, triple quoted strings to emulate shell heredocs. Substitution complex strings into recipe bodies with {ā€¦} can also lead to trouble as it may be split by the shell into multiple arguments depending on the presence of whitespace and quotes. Exporting complex strings as environment variables and referring to them with "$NAME" , note the double quotes, can also help. Putting all this together, to print a string verbatim to standard output, with all its various escape sequences and quotes undisturbed: export FOO := ''' a complicated string with some dis\tur\bi\ng escape sequences and "quotes" of 'different' kinds ''' bar : printf %s " $FOO" Alternatives and Prior Art There is no shortage of command runners! Some more or less similar alternatives to just include: make : The Unix build tool that inspired just . There are a few different modern day descendents of the original make , including FreeBSD Make and GNU Make . task : A YAML-based command runner written in Go. maid : A Markdown-based command runner written in JavaScript. microsoft/just : A JavaScript-based command runner written in JavaScript. cargo-make : A command runner for Rust projects. mmake : A wrapper around make with a number of improvements, including remote includes. robo : A YAML-based command runner written in Go. mask : A Markdown-based command runner written in Rust. makesure : A simple and portable command runner written in AWK and shell. haku : A make-like command runner written in Rust. mise : A development environment tool manager written in Rust supporting tasks in TOML files and standalone scripts. Contributing just welcomes your contributions! just is released under the maximally permissive CC0 public domain dedication and fallback license, so your changes must also be released under this license. Getting Started just is written in Rust. Use rustup to install a Rust toolchain. just is extensively tested. All new features must be covered by unit or integration tests. Unit tests are under src , live alongside the code being tested, and test code in isolation. Integration tests are in the tests directory and test the just binary from the outside by invoking just on a given justfile and set of command-line arguments, and checking the output. You should write whichever type of tests are easiest to write for your feature while still providing good test coverage. Unit tests are useful for testing new Rust functions that are used internally and as an aid for development. A good example are the unit tests which cover the unindent() function , used to unindent triple-quoted strings and backticks. unindent() has a bunch of tricky edge cases which are easy to exercise with unit tests that call unindent() directly. Integration tests are useful for making sure that the final behavior of the just binary is correct. unindent() is also covered by integration tests which make sure that evaluating a triple-quoted string produces the correct unindented value. However, there are not integration tests for all possible cases. These are covered by faster, more concise unit tests that call unindent() directly. Integration tests use the Test struct, a builder which allows for easily invoking just with a given justfile , arguments, and environment variables, and checking the program's stdout, stderr, and exit code . Contribution Workflow Make sure the feature is wanted. There should be an open issue about the feature with a comment from @casey saying that it's a good idea or seems reasonable. If there isn't, open a new issue and ask for feedback. There are lots of good features which can't be merged, either because they aren't backwards compatible, have an implementation which would overcomplicate the codebase, or go against just 's design philosophy. Settle on the design of the feature. If the feature has multiple possible implementations or syntaxes, make sure to nail down the details in the issue. Clone just and start hacking. The best workflow is to have the code you're working on in an editor alongside a job that re-runs tests whenever a file changes. You can run such a job by installing cargo-watch with cargo install cargo-watch and running just watch test . Add a failing test for your feature. Most of the time this will be an integration test which exercises the feature end-to-end. Look for an appropriate file to put the test in tests , or add a new file in tests and add a mod statement importing that file in tests/lib.rs . Implement the feature. Run just ci to make sure that all tests, lints, and checks pass. Requires mdBook and mdbook-linkcheck . Open a PR with the new code that is editable by maintainers. PRs often require rebasing and minor tweaks. If the PR is not editable by maintainers, each rebase and tweak will require a round trip of code review. Your PR may be summarily closed if it is not editable by maintainers. Incorporate feedback. Enjoy the sweet feeling of your PR getting merged! Feel free to open a draft PR at any time for discussion and feedback. Hints Here are some hints to get you started with specific kinds of new features, which you can use in addition to the contribution workflow above. Adding a New Attribute Write a new integration test in tests/attributes.rs . Add a new variant to the Attribute enum. Implement the functionality of the new attribute. Run just ci to make sure that all tests pass. Janus Janus is a tool for checking whether a change to just breaks or changes the interpretation of existing justfile s. It collects and analyzes public justfile s on GitHub. Before merging a particularly large or gruesome change, Janus should be run to make sure that nothing breaks. Don't worry about running Janus yourself, Casey will happily run it for you on changes that need it. Minimum Supported Rust Version The minimum supported Rust version, or MSRV, is current stable Rust. It may build on older versions of Rust, but this is not guaranteed. New Releases New releases of just are made frequently so that users quickly get access to new features. Release commit messages use the following template: Release x.y.z - Bump version: x.y.z ā†’ x.y.z - Update changelog - Update changelog contributor credits - Update dependencies - Update version references in readme Frequently Asked Questions What are the idiosyncrasies of Make that Just avoids? make has some behaviors which are confusing, complicated, or make it unsuitable for use as a general command runner. One example is that under some circumstances, make won't actually run the commands in a recipe. For example, if you have a file called test and the following makefile: test : . / test make will refuse to run your tests: $ make test make: `test' is up to date. make assumes that the test recipe produces a file called test . Since this file exists and the recipe has no other dependencies, make thinks that it doesn't have anything to do and exits. To be fair, this behavior is desirable when using make as a build system, but not when using it as a command runner. You can disable this behavior for specific targets using make 's built-in .PHONY target name , but the syntax is verbose and can be hard to remember. The explicit list of phony targets, written separately from the recipe definitions, also introduces the risk of accidentally defining a new non-phony target. In just , all recipes are treated as if they were phony. Other examples of make 's idiosyncrasies include the difference between = and := in assignments, the confusing error messages that are produced if you mess up your makefile, needing $$ to use environment variables in recipes, and incompatibilities between different flavors of make . What's the relationship between Just and Cargo build scripts? cargo build scripts have a pretty specific use, which is to control how cargo builds your Rust project. This might include adding flags to rustc invocations, building an external dependency, or running some kind of codegen step. just , on the other hand, is for all the other miscellaneous commands you might run as part of development. Things like running tests in different configurations, linting your code, pushing build artifacts to a server, removing temporary files, and the like. Also, although just is written in Rust, it can be used regardless of the language or build system your project uses. Further Ramblings I personally find it very useful to write a justfile for almost every project, big or small. On a big project with multiple contributors, it's very useful to have a file with all the commands needed to work on the project close at hand. There are probably different commands to test, build, lint, deploy, and the like, and having them all in one place is useful and cuts down on the time you have to spend telling people which commands to run and how to type them. And, with an easy place to put commands, it's likely that you'll come up with other useful things which are part of the project's collective wisdom, but which aren't written down anywhere, like the arcane commands needed for some part of your revision control workflow, to install all your project's dependencies, or all the random flags you might need to pass to the build system. Some ideas for recipes: Deploying/publishing the project Building in release mode vs debug mode Running in debug mode or with logging enabled Complex git workflows Updating dependencies Running different sets of tests, for example fast tests vs slow tests, or running them with verbose output Any complex set of commands that you really should write down somewhere, if only to be able to remember them Even for small, personal projects it's nice to be able to remember commands by name instead of ^Reverse searching your shell history, and it's a huge boon to be able to go into an old project written in a random language with a mysterious build system and know that all the commands you need to do whatever you need to do are in the justfile , and that if you type just something useful (or at least interesting!) will probably happen. For ideas for recipes, check out this project's justfile , or some of the justfile s out in the wild . Anyways, I think that's about it for this incredibly long-winded README. I hope you enjoy using just and find great success and satisfaction in all your computational endeavors! šŸ˜ø šŸ”¼ Back to the top!
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Dismiss alert [casey](https://github.com/casey) / **[just](https://github.com/casey/just)** Public - [Notifications](https://github.com/login?return_to=%2Fcasey%2Fjust) You must be signed in to change notification settings - [Fork 710](https://github.com/login?return_to=%2Fcasey%2Fjust) - [Star 32.5k](https://github.com/login?return_to=%2Fcasey%2Fjust) - [Code](https://github.com/casey/just) - [Issues 292](https://github.com/casey/just/issues) - [Pull requests 22](https://github.com/casey/just/pulls) - [Discussions](https://github.com/casey/just/discussions) - [Actions](https://github.com/casey/just/actions) - [Security and quality 0](https://github.com/casey/just/security) - [Insights](https://github.com/casey/just/pulse) Additional navigation options - [Code](https://github.com/casey/just) - [Issues](https://github.com/casey/just/issues) - [Pull requests](https://github.com/casey/just/pulls) - [Discussions](https://github.com/casey/just/discussions) - [Actions](https://github.com/casey/just/actions) - [Security and quality](https://github.com/casey/just/security) - [Insights](https://github.com/casey/just/pulse) # casey/just master [**3** Branches](https://github.com/casey/just/branches) [**170** Tags](https://github.com/casey/just/tags) Go to file Code Open more actions menu ## Folders and files | Name | Name | Last commit message | Last commit date | |---|---|---|---| | Latest commit [![alerque](https://avatars.githubusercontent.com/u/173595?v=4&size=40)](https://github.com/alerque)[alerque](https://github.com/casey/just/commits?author=alerque) [Don't use make syntax highlighting in vim (](https://github.com/casey/just/commit/2f1afab79c26eac0ca9ba04d5379d6ff11d64d39)[\#2906](https://github.com/casey/just/pull/2906)[)](https://github.com/casey/just/commit/2f1afab79c26eac0ca9ba04d5379d6ff11d64d39) success Apr 1, 2026 [2f1afab](https://github.com/casey/just/commit/2f1afab79c26eac0ca9ba04d5379d6ff11d64d39) Ā· Apr 1, 2026 History [1,627 Commits](https://github.com/casey/just/commits/master/) Open commit details 1,627 Commits | | | | ## Repository files navigation - [README](https://github.com/casey/just) - [Contributing](https://github.com/casey/just) - [CC0-1.0 license](https://github.com/casey/just) Table of Contents ā†—ļø # `just` [![crates.io version](https://camo.githubusercontent.com/acf15ac5756065b9f9d8590fd6f42709d004452ac2b4816823dc40528a74ffc5/68747470733a2f2f696d672e736869656c64732e696f2f6372617465732f762f6a7573742e737667)](https://crates.io/crates/just) [![build status](https://github.com/casey/just/actions/workflows/ci.yaml/badge.svg)](https://github.com/casey/just/actions/workflows/ci.yaml) [![downloads](https://camo.githubusercontent.com/3e2c0d79862f904f825c929a13c680efa566026e3f9965f5e0ad01fe2f9a503e/68747470733a2f2f696d672e736869656c64732e696f2f6769746875622f646f776e6c6f6164732f63617365792f6a7573742f746f74616c2e737667)](https://github.com/casey/just/releases) [![chat on discord](https://camo.githubusercontent.com/aa85ec82bf82099dca55b33244b99a0c7e22544ce66584ae3416aa9e2350bb3f/68747470733a2f2f696d672e736869656c64732e696f2f646973636f72642f3639353538303036393833373430363232383f6c6f676f3d646973636f7264)](https://discord.gg/ezYScXR) [![say thanks](https://camo.githubusercontent.com/ee843c523d57170345478ba1c560741cf66c2e266144266ccd1ab0c51b7f87a5/68747470733a2f2f696d672e736869656c64732e696f2f62616467652f5361792532305468616e6b732d212d3145414544422e737667)](mailto:casey@rodarmor.com?subject=Thanks%20for%20Just!) `just` is a handy way to save and run project-specific commands. This readme is also available as a [book](https://just.systems/man/en/). The book reflects the latest release, whereas the [readme on GitHub](https://github.com/casey/just/blob/master/README.md) reflects latest master. (äø­ę–‡ę–‡ę”£åœØ [čæ™é‡Œ](https://github.com/casey/just/blob/master/README.%E4%B8%AD%E6%96%87.md), åæ«ēœ‹čæ‡ę„!) Commands, called recipes, are stored in a file called `justfile` with syntax inspired by `make`: [![screenshot](https://raw.githubusercontent.com/casey/just/master/etc/screenshot.png)](https://raw.githubusercontent.com/casey/just/master/etc/screenshot.png) You can then run them with `just RECIPE`: ``` $ just test-all cc *.c -o main ./test --all Yay, all your tests passed! ``` `just` has a ton of useful features, and many improvements over `make`: - `just` is a command runner, not a build system, so it avoids much of [`make`'s complexity and idiosyncrasies](https://github.com/casey/just#what-are-the-idiosyncrasies-of-make-that-just-avoids). No need for `.PHONY` recipes\! - Linux, MacOS, Windows, and other reasonable unices are supported with no additional dependencies. (Although if your system doesn't have an `sh`, you'll need to [choose a different shell](https://github.com/casey/just#shell).) - Errors are specific and informative, and syntax errors are reported along with their source context. - Recipes can accept [command line arguments](https://github.com/casey/just#recipe-parameters). - Wherever possible, errors are resolved statically. Unknown recipes and circular dependencies are reported before anything runs. - `just` [loads `.env` files](https://github.com/casey/just#dotenv-settings), making it easy to populate environment variables. - Recipes can be [listed from the command line](https://github.com/casey/just#listing-available-recipes). - Command line completion scripts are [available for most popular shells](https://github.com/casey/just#shell-completion-scripts). - Recipes can be written in [arbitrary languages](https://github.com/casey/just#shebang-recipes), like Python or NodeJS. - `just` can be invoked from any subdirectory, not just the directory that contains the `justfile`. - And [much more](https://just.systems/man/en/)\! If you need help with `just` please feel free to open an issue or ping me on [Discord](https://discord.gg/ezYScXR). Feature requests and bug reports are always welcome\! ## Installation ### Prerequisites `just` should run on any system with a reasonable `sh`, including Linux, MacOS, and the BSDs. #### Windows On Windows, `just` works with the `sh` provided by [Git for Windows](https://git-scm.com/), [GitHub Desktop](https://desktop.github.com/), or [Cygwin](http://www.cygwin.com/). After installation, `sh` must be available in the `PATH` of the shell you want to invoke `just` from. If you'd rather not install `sh`, you can use the `shell` setting to use the shell of your choice. Like PowerShell: ``` # use PowerShell instead of sh: set shell := ["powershell.exe", "-c"] hello: Write-Host "Hello, world!" ``` ā€¦or `cmd.exe`: ``` # use cmd.exe instead of sh: set shell := ["cmd.exe", "/c"] list: dir ``` You can also set the shell using command-line arguments. For example, to use PowerShell, launch `just` with `--shell powershell.exe --shell-arg -c`. (PowerShell is installed by default on Windows 7 SP1 and Windows Server 2008 R2 S1 and later, and `cmd.exe` is quite fiddly, so PowerShell is recommended for most Windows users.) ### Packages #### Cross-platform | Package Manager | Package | Command | |---|---|---| | [arkade](https://github.com/alexellis/arkade) | just | `arkade get just` | | [asdf](https://asdf-vm.com/) | [just](https://github.com/olofvndrhr/asdf-just) | `asdf plugin add just` `asdf install just <version>` | | [Cargo](https://www.rust-lang.org/) | [just](https://crates.io/crates/just) | `cargo install just` | | [Cargo Binstall](https://github.com/cargo-bins/cargo-binstall) | [just](https://crates.io/crates/just) | `cargo binstall just` | | [Conda](https://docs.conda.io/projects/conda/en/latest/index.html) | [just](https://anaconda.org/conda-forge/just) | `conda install -c conda-forge just` | | [Homebrew](https://brew.sh/) | [just](https://formulae.brew.sh/formula/just) | `brew install just` | | [Nix](https://nixos.org/nix/) | [just](https://github.com/NixOS/nixpkgs/blob/master/pkgs/by-name/ju/just/package.nix) | `nix-env -iA nixpkgs.just` | | [npm](https://www.npmjs.com/) | [rust-just](https://www.npmjs.com/package/rust-just) | `npm install -g rust-just` | | [pipx](https://pipx.pypa.io/stable/) | [rust-just](https://pypi.org/project/rust-just/) | `pipx install rust-just` | | [Snap](https://snapcraft.io/) | [just](https://snapcraft.io/just) | `snap install --edge --classic just` | | [uv](https://docs.astral.sh/uv/) | [rust-just](https://pypi.org/project/rust-just/) | `uv tool install rust-just` | #### BSD | Operating System | Package Manager | Package | Command | |---|---|---|---| | [FreeBSD](https://www.freebsd.org/) | [pkg](https://www.freebsd.org/doc/handbook/pkgng-intro.html) | [just](https://www.freshports.org/deskutils/just/) | `pkg install just` | | [OpenBSD](https://www.openbsd.org/) | [pkg\_\*](https://www.openbsd.org/faq/faq15.html) | [just](https://cvsweb.openbsd.org/cgi-bin/cvsweb/ports/sysutils/just) | `pkg_add just` | #### Linux | Operating System | Package Manager | Package | Command | |---|---|---|---| | [Alpine](https://alpinelinux.org/) | [apk-tools](https://wiki.alpinelinux.org/wiki/Alpine_Linux_package_management) | [just](https://pkgs.alpinelinux.org/package/edge/community/x86_64/just) | `apk add just` | | [Arch](https://www.archlinux.org/) | [pacman](https://wiki.archlinux.org/title/Pacman) | [just](https://archlinux.org/packages/extra/x86_64/just/) | `pacman -S just` | | [Debian 13](https://debian.org/) and [Ubuntu 24.04](https://ubuntu.com/) derivatives | [apt](https://en.wikipedia.org/wiki/APT_\(software\)) | [just](https://packages.debian.org/trixie/just) | `apt install just` | | [Fedora](https://getfedora.org/) | [DNF](https://dnf.readthedocs.io/en/latest/) | [just](https://src.fedoraproject.org/rpms/rust-just) | `dnf install just` | | [Gentoo](https://www.gentoo.org/) | [Portage](https://wiki.gentoo.org/wiki/Portage) | [dev-build/just](https://packages.gentoo.org/packages/dev-build/just) | `emerge -av dev-build/just` | | [NixOS](https://nixos.org/nixos/) | [Nix](https://nixos.org/nix/) | [just](https://github.com/NixOS/nixpkgs/blob/master/pkgs/by-name/ju/just/package.nix) | `nix-env -iA nixos.just` | | [openSUSE](https://opensuse.org/) | [Zypper](https://en.opensuse.org/Portal:Zypper) | [just](https://build.opensuse.org/package/show/Base:System/just) | `zypper in just` | | [Solus](https://getsol.us/) | [eopkg](https://getsol.us/articles/package-management/basics/en) | [just](https://dev.getsol.us/source/just/) | `eopkg install just` | | [Void](https://voidlinux.org/) | [XBPS](https://wiki.voidlinux.org/XBPS) | [just](https://github.com/void-linux/void-packages/blob/master/srcpkgs/just/template) | `xbps-install -S just` | #### Windows | Package Manager | Package | Command | |---|---|---| | [Chocolatey](https://chocolatey.org/) | [just](https://github.com/michidk/just-choco) | `choco install just` | | [Scoop](https://scoop.sh/) | [just](https://github.com/ScoopInstaller/Main/blob/master/bucket/just.json) | `scoop install just` | | [Windows Package Manager](https://learn.microsoft.com/en-us/windows/package-manager/) | [Casey/Just](https://github.com/microsoft/winget-pkgs/tree/master/manifests/c/Casey/Just) | `winget install --id Casey.Just --exact` | #### macOS | Package Manager | Package | Command | |---|---|---| | [MacPorts](https://www.macports.org/) | [just](https://ports.macports.org/port/just/summary) | `port install just` | [![just package version table](https://camo.githubusercontent.com/0ebfbd07d3da9aaadf8971e68490391c726ac2c60f86a3b4400e5b55421acda8/68747470733a2f2f7265706f6c6f67792e6f72672f62616467652f766572746963616c2d616c6c7265706f732f6a7573742e737667)](https://camo.githubusercontent.com/0ebfbd07d3da9aaadf8971e68490391c726ac2c60f86a3b4400e5b55421acda8/68747470733a2f2f7265706f6c6f67792e6f72672f62616467652f766572746963616c2d616c6c7265706f732f6a7573742e737667) ### Pre-Built Binaries Pre-built binaries for Linux, MacOS, and Windows can be found on [the releases page](https://github.com/casey/just/releases). You can use the following command on Linux, MacOS, or Windows to download the latest release, just replace `DEST` with the directory where you'd like to put `just`: ``` curl --proto '=https' --tlsv1.2 -sSf https://just.systems/install.sh | bash -s -- --to DEST ``` For example, to install `just` to `~/bin`: ``` # create ~/bin mkdir -p ~/bin # download and extract just to ~/bin/just curl --proto '=https' --tlsv1.2 -sSf https://just.systems/install.sh | bash -s -- --to ~/bin # add `~/bin` to the paths that your shell searches for executables # this line should be added to your shells initialization file, # e.g. `~/.bashrc` or `~/.zshrc` export PATH="$PATH:$HOME/bin" # just should now be executable just --help ``` Note that `install.sh` may fail on GitHub Actions, or in other environments where many machines share IP addresses. `install.sh` calls GitHub APIs in order to determine the latest version of `just` to install, and those API calls are rate-limited on a per-IP basis. To make `install.sh` more reliable in such circumstances, pass a specific tag to install with `--tag`. Another way to avoid rate-limiting is to pass a GitHub authentication token to `install.sh` as an environment variable named `GITHUB_TOKEN`, allowing it to authenticate its requests. [Releases](https://github.com/casey/just/releases) include a `SHA256SUM` file which can be used to verify the integrity of pre-built binary archives. To verify a release, download the pre-built binary archive along with the `SHA256SUM` file and run: ``` shasum --algorithm 256 --ignore-missing --check SHA256SUMS ``` ### GitHub Actions `just` can be installed on GitHub Actions in a few ways. Using package managers pre-installed on GitHub Actions runners on MacOS with `brew install just`, and on Windows with `choco install just`. With [extractions/setup-just](https://github.com/extractions/setup-just): ``` - uses: extractions/setup-just@v3 with: just-version: 1.5.0 # optional semver specification, otherwise latest ``` Or with [taiki-e/install-action](https://github.com/taiki-e/install-action): ``` - uses: taiki-e/install-action@just ``` ### Docker `just` is available as a Docker image from [the GitHub Container Registry](https://ghcr.io/casey/just). To copy `just` into a Docker image, add the following line to your `Dockerfile`: ``` COPY --from=ghcr.io/casey/just:latest /just /usr/local/bin/ ``` After copying, `just` may also be used as part of a docker build: ``` RUN just ``` ### Release RSS Feed An [RSS feed](https://en.wikipedia.org/wiki/RSS) of `just` releases is available [here](https://github.com/casey/just/releases.atom). ### Node.js Installation [just-install](https://npmjs.com/package/just-install) can be used to automate installation of `just` in Node.js applications. `just` is a great, more robust alternative to npm scripts. If you want to include `just` in the dependencies of a Node.js application, `just-install` will install a local, platform-specific binary as part of the `npm install` command. This removes the need for every developer to install `just` independently using one of the processes mentioned above. After installation, the `just` command will work in npm scripts or with npx. It's great for teams who want to make the set up process for their project as easy as possible. For more information, see the [just-install README file](https://github.com/brombal/just-install#readme). ### Nix Flake The `just` repository includes a [`flake.nix`](https://github.com/casey/just/tree/master/flake.nix) that defines a [nix flake](https://nix.dev/concepts/flakes.html), allowing you to use `just` as an input to another flake: ``` { inputs = { just.url = "github:casey/just"; } outputs = {self, nixpkgs, just}: { } } ``` ## Backwards Compatibility With the release of version 1.0, `just` features a strong commitment to backwards compatibility and stability. Future releases will not introduce backwards incompatible changes that make existing `justfile`s stop working, or break working invocations of the command-line interface. This does not, however, preclude fixing outright bugs, even if doing so might break `justfiles` that rely on their behavior. There will never be a `just` 2.0. Any desirable backwards-incompatible changes will be opt-in on a per-`justfile` basis, so users may migrate at their leisure. Features that aren't yet ready for stabilization are marked as unstable and may be changed or removed at any time. Using unstable features produces an error by default, which can be suppressed by passing the `--unstable` flag, `set unstable`, or setting the environment variable `JUST_UNSTABLE`, to any value other than `false`, `0`, or the empty string. ## Editor Support `justfile` syntax is close enough to `make` that you may want to tell your editor to use `make` syntax highlighting for `just`. ### Vim and Neovim Vim version 9.1.1042 or better and Neovim version 0.11 or better support Justfile syntax highlighting out of the box, thanks to [pbnj](https://github.com/pbnj). #### `vim-just` The [vim-just](https://github.com/NoahTheDuke/vim-just) plugin provides syntax highlighting for `justfile`s. Install it with your favorite package manager, like [Plug](https://github.com/junegunn/vim-plug): ``` call plug#begin() Plug 'NoahTheDuke/vim-just' call plug#end() ``` Or with Vim's built-in package support: ``` mkdir -p ~/.vim/pack/vendor/start cd ~/.vim/pack/vendor/start git clone https://github.com/NoahTheDuke/vim-just.git ``` #### `tree-sitter-just` [tree-sitter-just](https://github.com/IndianBoy42/tree-sitter-just) is an [Nvim Treesitter](https://github.com/nvim-treesitter/nvim-treesitter) plugin for Neovim. ### Emacs [just-mode](https://github.com/leon-barrett/just-mode.el) provides syntax highlighting and automatic indentation of `justfile`s. It is available on [MELPA](https://melpa.org/) as [just-mode](https://melpa.org/#/just-mode). [justl](https://github.com/psibi/justl.el) provides commands for executing and listing recipes. You can add the following to an individual `justfile` to enable `make` mode on a per-file basis: ``` # Local Variables: # mode: makefile # End: ``` ### Visual Studio Code An extension for VS Code is [available here](https://github.com/nefrob/vscode-just). Unmaintained VS Code extensions include [skellock/vscode-just](https://github.com/skellock/vscode-just) and [sclu1034/vscode-just](https://github.com/sclu1034/vscode-just). ### JetBrains IDEs A plugin for JetBrains IDEs by [linux\_china](https://github.com/linux-china) is [available here](https://plugins.jetbrains.com/plugin/18658-just). ### Kakoune Kakoune supports `justfile` syntax highlighting out of the box, thanks to TeddyDD. ### Helix [Helix](https://helix-editor.com/) supports `justfile` syntax highlighting out-of-the-box since version 23.05. ### Sublime Text The [Just package](https://github.com/nk9/just_sublime) by [nk9](https://github.com/nk9) with `just` syntax and some other tools is available on [PackageControl](https://packagecontrol.io/packages/Just). ### Micro [Micro](https://micro-editor.github.io/) supports Justfile syntax highlighting out of the box, thanks to [tomodachi94](https://github.com/tomodachi94). ### Zed The [zed-just](https://github.com/jackTabsCode/zed-just/) extension by [jackTabsCode](https://github.com/jackTabsCode) is available on the [Zed extensions page](https://zed.dev/extensions?query=just). ### Other Editors Feel free to send me the commands necessary to get syntax highlighting working in your editor of choice so that I may include them here. ### Language Server Protocol [just-lsp](https://github.com/terror/just-lsp) provides a [language server protocol](https://en.wikipedia.org/wiki/Language_Server_Protocol) implementation, enabling features such as go-to-definition, inline diagnostics, and code completion. ### Model Context Protocol [just-mcp](http://github.com/promptexecution/just-mcp) provides a [model context protocol](https://en.wikipedia.org/wiki/Model_Context_Protocol) adapter to allow LLMs to query the contents of `justfiles` and run recipes. ## Quick Start See the installation section for how to install `just` on your computer. Try running `just --version` to make sure that it's installed correctly. For an overview of the syntax, check out [this cheatsheet](https://cheatography.com/linux-china/cheat-sheets/justfile/). Once `just` is installed and working, create a file named `justfile` in the root of your project with the following contents: ``` recipe-name: echo 'This is a recipe!' # this is a comment another-recipe: @echo 'This is another recipe.' ``` When you invoke `just` it looks for file `justfile` in the current directory and upwards, so you can invoke it from any subdirectory of your project. The search for a `justfile` is case insensitive, so any case, like `Justfile`, `JUSTFILE`, or `JuStFiLe`, will work. `just` will also look for files with the name `.justfile`, in case you'd like to hide a `justfile`. Running `just` with no arguments runs the first recipe in the `justfile`: ``` $ just echo 'This is a recipe!' This is a recipe! ``` One or more arguments specify the recipe(s) to run: ``` $ just another-recipe This is another recipe. ``` `just` prints each command to standard error before running it, which is why `echo 'This is a recipe!'` was printed. This is suppressed for lines starting with `@`, which is why `echo 'This is another recipe.'` was not printed. Recipes stop running if a command fails. Here `cargo publish` will only run if `cargo test` succeeds: ``` publish: cargo test # tests passed, time to publish! cargo publish ``` Recipes can depend on other recipes. Here the `test` recipe depends on the `build` recipe, so `build` will run before `test`: ``` build: cc main.c foo.c bar.c -o main test: build ./test sloc: @echo "`wc -l *.c` lines of code" ``` ``` $ just test cc main.c foo.c bar.c -o main ./test testingā€¦ all tests passed! ``` Recipes without dependencies will run in the order they're given on the command line: ``` $ just build sloc cc main.c foo.c bar.c -o main 1337 lines of code ``` Dependencies will always run first, even if they are passed after a recipe that depends on them: ``` $ just test build cc main.c foo.c bar.c -o main ./test testingā€¦ all tests passed! ``` Recipes may depend on recipes in submodules: ``` mod foo baz: foo::bar ``` ## Examples A variety of `justfile`s can be found in the [examples directory](https://github.com/casey/just/tree/master/examples) and on [GitHub](https://github.com/search?q=path%3A**%2Fjustfile&type=code). ## Features ### The Default Recipe When `just` is invoked without a recipe, it runs the recipe with the `[default]` attribute, or the first recipe in the `justfile` if no recipe has the `[default]` attribute. This recipe might be the most frequently run command in the project, like running the tests: ``` test: cargo test ``` You can also use dependencies to run multiple recipes by default: ``` default: lint build test build: echo Buildingā€¦ test: echo Testingā€¦ lint: echo Lintingā€¦ ``` If no recipe makes sense as the default recipe, you can add a recipe to the beginning of your `justfile` that lists the available recipes: ``` default: just --list ``` ### Listing Available Recipes Recipes can be listed in alphabetical order with `just --list`: ``` $ just --list Available recipes: build test deploy lint ``` Recipes in [submodules](https://github.com/casey/just#modules) can be listed with `just --list PATH`, where `PATH` is a space- or `::`\-separated module path: ``` $ cat justfile mod foo $ cat foo.just mod bar $ cat bar.just baz: $ just --list foo bar Available recipes: baz $ just --list foo::bar Available recipes: baz ``` `just --summary` is more concise: ``` $ just --summary build test deploy lint ``` Pass `--unsorted` to print recipes in the order they appear in the `justfile`: ``` test: echo 'Testing!' build: echo 'Building!' ``` ``` $ just --list --unsorted Available recipes: test build ``` ``` $ just --summary --unsorted test build ``` If you'd like `just` to default to listing the recipes in the `justfile`, you can use this as your default recipe: ``` default: @just --list ``` Note that you may need to add `--justfile {{justfile()}}` to the line above. Without it, if you executed `just -f /some/distant/justfile -d .` or `just -f ./non-standard-justfile`, the plain `just --list` inside the recipe would not necessarily use the file you provided. It would try to find a justfile in your current path, maybe even resulting in a `No justfile found` error. The heading text can be customized with `--list-heading`: ``` $ just --list --list-heading $'Cool stuffā€¦\n' Cool stuffā€¦ test build ``` And the indentation can be customized with `--list-prefix`: ``` $ just --list --list-prefix Ā·Ā·Ā·Ā· Available recipes: Ā·Ā·Ā·Ā·test Ā·Ā·Ā·Ā·build ``` The argument to `--list-heading` replaces both the heading and the newline following it, so it should contain a newline if non-empty. It works this way so you can suppress the heading line entirely by passing the empty string: ``` $ just --list --list-heading '' test build ``` ### Invoking Multiple Recipes Multiple recipes may be invoked on the command line at once: ``` build: make web serve: python3 -m http.server -d out 8000 ``` ``` $ just build serve make web python3 -m http.server -d out 8000 ``` Keep in mind that recipes with parameters will swallow arguments, even if they match the names of other recipes: ``` build project: make {{project}} serve: python3 -m http.server -d out 8000 ``` ``` $ just build serve make: *** No rule to make target `serve'. Stop. ``` The `--one` flag can be used to restrict command-line invocations to a single recipe: ``` $ just --one build serve error: Expected 1 command-line recipe invocation but found 2. ``` ### Working Directory By default, recipes run with the working directory set to the directory that contains the `justfile`. The `[no-cd]` attribute can be used to make recipes run with the working directory set to directory in which `just` was invoked. ``` @foo: pwd [no-cd] @bar: pwd ``` ``` $ cd subdir $ just foo / $ just bar /subdir ``` You can override the working directory for all recipes with `set working-directory := 'ā€¦'`: ``` set working-directory := 'bar' @foo: pwd ``` ``` $ pwd /home/bob $ just foo /home/bob/bar ``` You can override the working directory for a specific recipe with the `working-directory` attribute1\.38.0: ``` [working-directory: 'bar'] @foo: pwd ``` ``` $ pwd /home/bob $ just foo /home/bob/bar ``` The argument to the `working-directory` setting or `working-directory` attribute may be absolute or relative. If it is relative it is interpreted relative to the default working directory. ### Aliases Aliases allow recipes to be invoked on the command line with alternative names: ``` alias b := build build: echo 'Building!' ``` ``` $ just b echo 'Building!' Building! ``` The target of an alias may be a recipe in a submodule: ``` mod foo alias baz := foo::bar ``` ### Settings Settings control interpretation and execution. Each setting may be specified at most once, anywhere in the `justfile`. For example: ``` set shell := ["zsh", "-cu"] foo: # this line will be run as `zsh -cu 'ls **/*.txt'` ls **/*.txt ``` #### Table of Settings | Name | Value | Default | Description | |---|---|---|---| | `allow-duplicate-recipes` | boolean | `false` | Allow recipes appearing later in a `justfile` to override earlier recipes with the same name. | | `allow-duplicate-variables` | boolean | `false` | Allow variables appearing later in a `justfile` to override earlier variables with the same name. | | `dotenv-filename` | string | \- | Load a `.env` file with a custom name, if present. | | `dotenv-load` | boolean | `false` | Load a `.env` file, if present. | | `dotenv-override` | boolean | `false` | Override existing environment variables with values from the `.env` file. | | `dotenv-path` | string | \- | Load a `.env` file from a custom path and error if not present. Overrides `dotenv-filename`. | | `dotenv-required` | boolean | `false` | Error if a `.env` file isn't found. | | `export` | boolean | `false` | Export all variables as environment variables. | | `fallback` | boolean | `false` | Search `justfile` in parent directory if the first recipe on the command line is not found. | | `ignore-comments` | boolean | `false` | Ignore recipe lines beginning with `#`. | | `lazy`1\.47.0 | boolean | `false` | Don't evaluate unused variables. | | `positional-arguments` | boolean | `false` | Pass positional arguments. | | `quiet` | boolean | `false` | Disable echoing recipe lines before executing. | | `script-interpreter`1\.33.0 | `[COMMAND, ARGSā€¦]` | `['sh', '-eu']` | Set command used to invoke recipes with empty `[script]` attribute. | | `shell` | `[COMMAND, ARGSā€¦]` | \- | Set command used to invoke recipes and evaluate backticks. | | `tempdir` | string | \- | Create temporary directories in `tempdir` instead of the system default temporary directory. | | `unstable`1\.31.0 | boolean | `false` | Enable unstable features. | | `windows-powershell` | boolean | `false` | Use PowerShell on Windows as default shell. (Deprecated. Use `windows-shell` instead. | | `windows-shell` | `[COMMAND, ARGSā€¦]` | \- | Set the command used to invoke recipes and evaluate backticks. | | `working-directory`1\.33.0 | string | \- | Set the working directory for recipes and backticks, relative to the default working directory. | Boolean settings can be written as: ``` set NAME ``` Which is equivalent to: ``` set NAME := true ``` Non-boolean settings can be set to both strings and expressions.1\.46.0 However, because settings affect the behavior of backticks and many functions, those expressions may not contain backticks or function calls, directly or transitively via reference. #### Allow Duplicate Recipes If `allow-duplicate-recipes` is set to `true`, defining multiple recipes with the same name is not an error and the last definition is used. Defaults to `false`. ``` set allow-duplicate-recipes @foo: echo foo @foo: echo bar ``` ``` $ just foo bar ``` #### Allow Duplicate Variables If `allow-duplicate-variables` is set to `true`, defining multiple variables with the same name is not an error and the last definition is used. Defaults to `false`. ``` set allow-duplicate-variables a := "foo" a := "bar" @foo: echo {{a}} ``` ``` $ just foo bar ``` #### Dotenv Settings If any of `dotenv-load`, `dotenv-filename`, `dotenv-override`, `dotenv-path`, or `dotenv-required` are set, `just` will try to load environment variables from a file. If `dotenv-path` is set, `just` will look for a file at the given path, which may be absolute, or relative to the working directory. The command-line option `--dotenv-path`, short form `-E`, can be used to set or override `dotenv-path` at runtime. If `dotenv-filename` is set `just` will look for a file at the given path, relative to the working directory and each of its ancestors. If `dotenv-filename` is not set, but `dotenv-load` or `dotenv-required` are set, just will look for a file named `.env`, relative to the working directory and each of its ancestors. `dotenv-filename` and `dotenv-path` are similar, but `dotenv-path` is only checked relative to the working directory, whereas `dotenv-filename` is checked relative to the working directory and each of its ancestors. It is not an error if an environment file is not found, unless `dotenv-required` is set. The loaded variables are environment variables, not `just` variables, and so must be accessed using `$VARIABLE_NAME` in recipes and backticks. If `dotenv-override` is set, variables from the environment file will override existing environment variables. For example, if your `.env` file contains: ``` # a comment, will be ignored DATABASE_ADDRESS=localhost:6379 SERVER_PORT=1337 ``` And your `justfile` contains: ``` set dotenv-load serve: @echo "Starting server with database $DATABASE_ADDRESS on port $SERVER_PORTā€¦" ./server --database $DATABASE_ADDRESS --port $SERVER_PORT ``` `just serve` will output: ``` $ just serve Starting server with database localhost:6379 on port 1337ā€¦ ./server --database $DATABASE_ADDRESS --port $SERVER_PORT ``` #### Export The `export` setting causes all `just` variables to be exported as environment variables. Defaults to `false`. ``` set export a := "hello" @foo b: echo $a echo $b ``` ``` $ just foo goodbye hello goodbye ``` #### Lazy The `lazy` setting1\.47.0 causes the evaluator to skip evaluating unused variables. This can be beneficial when a `justfile` contains variables that are expensive to evaluate but only sometimes used. In the following `justfile`, `token` will be skipped when only invoking `bar`: ``` set lazy token := `expensive-script-to-get-credentials` foo: curl -H "Authorization: Bearer {{ token }}" https://example.com/foo bar: cargo test ``` Because `just` cannot determine when exported variables are used, assignments with `export` and assignments in a module with `set export` will always be evaluated. #### Positional Arguments If `positional-arguments` is `true`, recipe arguments will be passed as positional arguments to commands. For linewise recipes, argument `$0` will be the name of the recipe. For example, running this recipe: ``` set positional-arguments @foo bar: echo $0 echo $1 ``` Will produce the following output: ``` $ just foo hello foo hello ``` When using an `sh`\-compatible shell, such as `bash` or `zsh`, `$@` expands to the positional arguments given to the recipe, starting from one. When used within double quotes as `"$@"`, arguments including whitespace will be passed on as if they were double-quoted. That is, `"$@"` is equivalent to `"$1" "$2"`ā€¦ When there are no positional parameters, `"$@"` and `$@` expand to nothing (i.e., they are removed). This example recipe will print arguments one by one on separate lines: ``` set positional-arguments @test *args='': bash -c 'while (( "$#" )); do echo - $1; shift; done' -- "$@" ``` Running it with *two* arguments: ``` $ just test foo "bar baz" - foo - bar baz ``` Positional arguments may also be turned on a per-recipe basis with the `[positional-arguments]` attribute1\.29.0: ``` [positional-arguments] @foo bar: echo $0 echo $1 ``` Note that PowerShell does not handle positional arguments in the same way as other shells, so turning on positional arguments will likely break recipes that use PowerShell. If using PowerShell 7.4 or better, the `-CommandWithArgs` flag will make positional arguments work as expected: ``` set shell := ['pwsh.exe', '-CommandWithArgs'] set positional-arguments print-args a b c: Write-Output @($args[1..($args.Count - 1)]) ``` #### Shell The `shell` setting controls the command used to invoke recipe lines and backticks. Shebang recipes are unaffected. The default shell is `sh -cu`. ``` # use python3 to execute recipe lines and backticks set shell := ["python3", "-c"] # use print to capture result of evaluation foos := `print("foo" * 4)` foo: print("Snake snake snake snake.") print("{{foos}}") ``` `just` passes the command to be executed as an argument. Many shells will need an additional flag, often `-c`, to make them evaluate the first argument. ##### Windows Shell `just` uses `sh` on Windows by default. To use a different shell on Windows, use `windows-shell`: ``` set windows-shell := ["powershell.exe", "-NoLogo", "-Command"] hello: Write-Host "Hello, world!" ``` See [powershell.just](https://github.com/casey/just/blob/master/examples/powershell.just) for a justfile that uses PowerShell on all platforms. ##### Windows PowerShell *`set windows-powershell` uses the legacy `powershell.exe` binary, and is no longer recommended. See the `windows-shell` setting above for a more flexible way to control which shell is used on Windows.* `just` uses `sh` on Windows by default. To use `powershell.exe` instead, set `windows-powershell` to true. ``` set windows-powershell := true hello: Write-Host "Hello, world!" ``` ##### Python 3 ``` set shell := ["python3", "-c"] ``` ##### Bash ``` set shell := ["bash", "-uc"] ``` ##### Z Shell ``` set shell := ["zsh", "-uc"] ``` ##### Fish ``` set shell := ["fish", "-c"] ``` ##### Nushell ``` set shell := ["nu", "-c"] ``` If you want to change the default table mode to `light`: ``` set shell := ['nu', '-m', 'light', '-c'] ``` *[Nushell](https://github.com/nushell/nushell) was written in Rust, and **has cross-platform support for Windows / macOS and Linux**.* ### Documentation Comments Comments immediately preceding a recipe will appear in `just --list`: ``` # build stuff build: ./bin/build # test stuff test: ./bin/test ``` ``` $ just --list Available recipes: build # build stuff test # test stuff ``` The `[doc]` attribute can be used to set or suppress a recipe's doc comment: ``` # This comment won't appear [doc('Build stuff')] build: ./bin/build # This one won't either [doc] test: ./bin/test ``` ``` $ just --list Available recipes: build # Build stuff test ``` ### Variables and Assignments Module-level variables may be created by assigning them a value with `:=`: ``` foo := "hello" bar := "world" baz: echo {{ foo + " " + bar }} ``` All variables in a module may be printed: ``` $ just --evaluate bar := "world" foo := "hello" ``` Or the value of a single variable: ``` $ just --evalaute foo hello ``` All variables in a submodule or a single variable in a submodule may be printed with a path to the submodule or variablemaster: ``` $ just --evaluate bob::bar x := "world" y := "hello" $ just --evaluate bob::bar::y hello ``` The format of exported variables may be controlled with `--evaluate-format`master: ``` $ just --evaluate --evaluate-format shell bar="world" foo="hello" ``` The default format is `--evaluate-format just`: ``` $ just --evaluate --evaluate-format just bar := "world" foo := "hello" ``` ### Expressions and Substitutions Various operators and function calls are supported in expressions, which may be used in assignments, default recipe arguments, and inside recipe body `{{ā€¦}}` substitutions. ``` tmpdir := `mktemp -d` version := "0.2.7" tardir := tmpdir / "awesomesauce-" + version tarball := tardir + ".tar.gz" config := quote(config_dir() / ".project-config") publish: rm -f {{tarball}} mkdir {{tardir}} cp README.md *.c {{ config }} {{tardir}} tar zcvf {{tarball}} {{tardir}} scp {{tarball}} me@server.com:release/ rm -rf {{tarball}} {{tardir}} ``` #### Concatenation The `+` operator returns the left-hand argument concatenated with the right-hand argument: ``` foobar := 'foo' + 'bar' ``` #### Logical Operators The logical operators `&&` and `||` can be used to coalesce string values1\.37.0, similar to Python's `and` and `or`. These operators consider the empty string `''` to be false, and all other strings to be true. These operators are currently unstable. The `&&` operator returns the empty string if the left-hand argument is the empty string, otherwise it returns the right-hand argument: ``` foo := '' && 'goodbye' # '' bar := 'hello' && 'goodbye' # 'goodbye' ``` The `||` operator returns the left-hand argument if it is non-empty, otherwise it returns the right-hand argument: ``` foo := '' || 'goodbye' # 'goodbye' bar := 'hello' || 'goodbye' # 'hello' ``` #### Joining Paths The `/` operator can be used to join two strings with a slash: ``` foo := "a" / "b" ``` ``` $ just --evaluate foo a/b ``` Note that a `/` is added even if one is already present: ``` foo := "a/" bar := foo / "b" ``` ``` $ just --evaluate bar a//b ``` Absolute paths can also be constructed1\.5.0: ``` foo := / "b" ``` ``` $ just --evaluate foo /b ``` The `/` operator uses the `/` character, even on Windows. Thus, using the `/` operator should be avoided with paths that use universal naming convention (UNC), i.e., those that start with `\?`, since forward slashes are not supported with UNC paths. #### Escaping `{{` To write a recipe containing `{{`, use `{{{{`: ``` braces: echo 'I {{{{LOVE}} curly braces!' ``` (An unmatched `}}` is ignored, so it doesn't need to be escaped.) Another option is to put all the text you'd like to escape inside of an interpolation: ``` braces: echo '{{'I {{LOVE}} curly braces!'}}' ``` Yet another option is to use `{{ "{{" }}`: ``` braces: echo 'I {{ "{{" }}LOVE}} curly braces!' ``` ### Strings `'single'`, `"double"`, and `'''triple'''` quoted string literals are supported. Unlike in recipe bodies, `{{ā€¦}}` interpolations are not supported inside strings. Double-quoted strings support escape sequences: ``` carriage-return := "\r" double-quote := "\"" newline := "\n" no-newline := "\ " slash := "\\" tab := "\t" unicode-codepoint := "\u{1F916}" ``` ``` $ just --evaluate "arriage-return := " double-quote := """ newline := " " no-newline := "" slash := "\" tab := " " unicode-codepoint := "šŸ¤–" ``` The unicode character escape sequence `\u{ā€¦}`1\.36.0 accepts up to six hex digits. Strings may contain line breaks: ``` single := ' hello ' double := " goodbye " ``` Single-quoted strings do not recognize escape sequences: ``` escapes := '\t\n\r\"\\' ``` ``` $ just --evaluate escapes := "\t\n\r\"\\" ``` Indented versions of both single- and double-quoted strings, delimited by triple single- or double-quotes, are supported. Indented string lines are stripped of a leading line break, and leading whitespace common to all non-blank lines: ``` # this string will evaluate to `foo\nbar\n` x := ''' foo bar ''' # this string will evaluate to `abc\n wuv\nxyz\n` y := """ abc wuv xyz """ ``` Similar to unindented strings, indented double-quoted strings process escape sequences, and indented single-quoted strings ignore escape sequences. Escape sequence processing takes place after unindentation. The unindentation algorithm does not take escape-sequence produced whitespace or newlines into account. #### Shell-expanded strings Strings prefixed with `x` are shell expanded1\.27.0: ``` foobar := x'~/$FOO/${BAR}' ``` | Value | Replacement | |---|---| | `$VAR` | value of environment variable `VAR` | | `${VAR}` | value of environment variable `VAR` | | `${VAR:-DEFAULT}` | value of environment variable `VAR`, or `DEFAULT` if `VAR` is not set | | Leading `~` | path to current user's home directory | | Leading `~USER` | path to `USER`'s home directory | This expansion is performed at compile time, so variables from `.env` files and exported `just` variables cannot be used. However, this allows shell expanded strings to be used in places like settings and import paths, which cannot depend on `just` variables and `.env` files. #### Format strings Strings prefixed with `f` are format strings1\.44.0: ``` name := "world" message := f'Hello, {{name}}!' ``` Format strings may contain interpolations delimited with `{{ā€¦}}` that contain expressions. Format strings evaluate to the concatenated string fragments and evaluated expressions. Use `{{{{` to include a literal `{{` in a format string: ``` foo := f'I {{{{LOVE} curly braces!' ``` ### Sigils Commands in linewise recipes may be prefixed with any combination of the sigils `-`, `@`, and `?`. The `@` sigil toggles command echoing: ``` foo: @echo "This line won't be echoed!" echo "This line will be echoed!" @bar: @echo "This line will be echoed!" echo "This line won't be echoed!" ``` The `-` sigil cause recipe execution to continue even if the command returns a nonzero exit status: ``` # execution will continue, even if bar doesn't exist foo: -rmdir bar mkdir bar echo 'so much good stuff' > bar/stuff.txt ``` The `?` sigil1\.47.0 causes the current recipe to stop executing if the command exits with status code `1`, however execution of other recipes will continue. Exit status `0` causes the current recipe to continue execution as normal. All other exit codes are reserved and should not be used, as they may be given meaning in a future version of `just`. If the `guards` setting is unset or false, `?` sigils are ignored and instead treated as part of the command. ``` set guards @foo: bar echo FOO @bar: ?[[ -f baz ]] echo BAR ``` ``` $ just foo FOO $ touch baz $ just foo BAR FOO ``` ### Functions `just` provides many built-in functions for use in expressions, including recipe body `{{ā€¦}}` substitutions, assignments, and default parameter values. All functions ending in `_directory` can be abbreviated to `_dir`. So `home_directory()` can also be written as `home_dir()`. In addition, `invocation_directory_native()` can be abbreviated to `invocation_dir_native()`. #### System Information - `arch()` ā€” Instruction set architecture. Possible values are: `"aarch64"`, `"arm"`, `"asmjs"`, `"hexagon"`, `"mips"`, `"msp430"`, `"powerpc"`, `"powerpc64"`, `"s390x"`, `"sparc"`, `"wasm32"`, `"x86"`, `"x86_64"`, and `"xcore"`. - `num_cpus()`1\.15.0 - Number of logical CPUs. - `os()` ā€” Operating system. Possible values are: `"android"`, `"bitrig"`, `"dragonfly"`, `"emscripten"`, `"freebsd"`, `"haiku"`, `"ios"`, `"linux"`, `"macos"`, `"netbsd"`, `"openbsd"`, `"solaris"`, and `"windows"`. - `os_family()` ā€” Operating system family; possible values are: `"unix"` and `"windows"`. For example: ``` system-info: @echo "This is an {{arch()}} machine". ``` ``` $ just system-info This is an x86_64 machine ``` The `os_family()` function can be used to create cross-platform `justfile`s that work on various operating systems. For an example, see [cross-platform.just](https://github.com/casey/just/blob/master/examples/cross-platform.just) file. #### External Commands - `shell(command, args...)`1\.27.0 returns the standard output of shell script `command` with zero or more positional arguments `args`. The shell used to interpret `command` is the same shell that is used to evaluate recipe lines, and can be changed with `set shell := [ā€¦]`. `command` is passed as the first argument, so if the command is `'echo $@'`, the full command line, with the default shell command `sh -cu` and `args` `'foo'` and `'bar'` will be: ``` 'sh' '-cu' 'echo $@' 'echo $@' 'foo' 'bar' ``` This is so that `$@` works as expected, and `$1` refers to the first argument. `$@` does not include the first positional argument, which is expected to be the name of the program being run. ``` # arguments can be variables or expressions file := '/sys/class/power_supply/BAT0/status' bat0stat := shell('cat $1', file) # commands can be variables or expressions command := 'wc -l' output := shell(command + ' "$1"', 'main.c') # arguments referenced by the shell command must be used empty := shell('echo', 'foo') full := shell('echo $1', 'foo') error := shell('echo $1') ``` ``` # Using python as the shell. Since `python -c` sets `sys.argv[0]` to `'-c'`, # the first "real" positional argument will be `sys.argv[2]`. set shell := ["python3", "-c"] olleh := shell('import sys; print(sys.argv[2][::-1])', 'hello') ``` #### Environment Variables - `env(key)`1\.15.0 ā€” Retrieves the environment variable with name `key`, aborting if it is not present. ``` home_dir := env('HOME') test: echo "{{home_dir}}" ``` ``` $ just /home/user1 ``` - `env(key, default)`1\.15.0 ā€” Retrieves the environment variable with name `key`, returning `default` if it is not present. - `env_var(key)` ā€” Deprecated alias for `env(key)`. - `env_var_or_default(key, default)` ā€” Deprecated alias for `env(key, default)`. A default can be substituted for an empty environment variable value with the `||` operator, currently unstable: ``` set unstable foo := env('FOO', '') || 'DEFAULT_VALUE' ``` #### Executables - `require(name)`1\.39.0 ā€” Search directories in the `PATH` environment variable for the executable `name` and return its full path, or halt with an error if no executable with `name` exists. ``` bash := require("bash") @test: echo "bash: '{{bash}}'" ``` ``` $ just bash: '/bin/bash' ``` - `which(name)`1\.39.0 ā€” Search directories in the `PATH` environment variable for the executable `name` and return its full path, or the empty string if no executable with `name` exists. Currently unstable. ``` set unstable bosh := which("bosh") @test: echo "bosh: '{{bosh}}'" ``` ``` $ just bosh: '' ``` #### Invocation Information - `is_dependency()` - Returns the string `true` if the current recipe is being run as a dependency of another recipe, rather than being run directly, otherwise returns the string `false`. #### Invocation Directory - `invocation_directory()` - Retrieves the absolute path to the current directory when `just` was invoked, before `just` changed it (chdir'd) prior to executing commands. On Windows, `invocation_directory()` uses `cygpath` to convert the invocation directory to a Cygwin-compatible `/`\-separated path. Use `invocation_directory_native()` to return the verbatim invocation directory on all platforms. For example, to call `rustfmt` on files just under the "current directory" (from the user/invoker's perspective), use the following rule: ``` rustfmt: find {{invocation_directory()}} -name \*.rs -exec rustfmt {} \; ``` Alternatively, if your command needs to be run from the current directory, you could use (e.g.): ``` build: cd {{invocation_directory()}}; ./some_script_that_needs_to_be_run_from_here ``` - `invocation_directory_native()` - Retrieves the absolute path to the current directory when `just` was invoked, before `just` changed it (chdir'd) prior to executing commands. #### Justfile and Justfile Directory - `justfile()` - Retrieves the path of the current `justfile`. - `justfile_directory()` - Retrieves the path of the parent directory of the current `justfile`. For example, to run a command relative to the location of the current `justfile`: ``` script: {{justfile_directory()}}/scripts/some_script ``` #### Source and Source Directory - `source_file()`1\.27.0 - Retrieves the path of the current source file. - `source_directory()`1\.27.0 - Retrieves the path of the parent directory of the current source file. `source_file()` and `source_directory()` behave the same as `justfile()` and `justfile_directory()` in the root `justfile`, but will return the path and directory, respectively, of the current `import` or `mod` source file when called from within an import or submodule. #### Module and Module Directory - `module_file()` - Retrieves the path of the current module file. - `module_directory()` - Retrieves the path of the parent directory of the current module file. `module_file()` and `module_directory()` behave the same as `justfile()` and `justfile_directory()` in the root `justfile`, but will return the path and directory, respectively, of the current `mod` source file when called from within submodule. #### Just Executable - `just_executable()` - Absolute path to the `just` executable. For example: ``` executable: @echo The executable is at: {{just_executable()}} ``` ``` $ just The executable is at: /bin/just ``` #### Just Process ID - `just_pid()` - Process ID of the `just` executable. For example: ``` pid: @echo The process ID is: {{ just_pid() }} ``` ``` $ just The process ID is: 420 ``` #### String Manipulation - `append(suffix, s)`1\.27.0 Append `suffix` to whitespace-separated strings in `s`. `append('/src', 'foo bar baz')` ā†’ `'foo/src bar/src baz/src'` - `prepend(prefix, s)`1\.27.0 Prepend `prefix` to whitespace-separated strings in `s`. `prepend('src/', 'foo bar baz')` ā†’ `'src/foo src/bar src/baz'` - `encode_uri_component(s)`1\.27.0 - Percent-encode characters in `s` except `[A-Za-z0-9_.!~*'()-]`, matching the behavior of the [JavaScript `encodeURIComponent` function](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/encodeURIComponent). - `quote(s)` - Replace all single quotes with `'\''` and prepend and append single quotes to `s`. This is sufficient to escape special characters for many shells, including most Bourne shell descendants. - `replace(s, from, to)` - Replace all occurrences of `from` in `s` with `to`. - `replace_regex(s, regex, replacement)` - Replace all occurrences of `regex` in `s` with `replacement`. Regular expressions are provided by the [Rust `regex` crate](https://docs.rs/regex/latest/regex/). See the [syntax documentation](https://docs.rs/regex/latest/regex/#syntax) for usage examples. Capture groups are supported. The `replacement` string uses [Replacement string syntax](https://docs.rs/regex/latest/regex/struct.Regex.html#replacement-string-syntax). - `trim(s)` - Remove leading and trailing whitespace from `s`. - `trim_end(s)` - Remove trailing whitespace from `s`. - `trim_end_match(s, substring)` - Remove suffix of `s` matching `substring`. - `trim_end_matches(s, substring)` - Repeatedly remove suffixes of `s` matching `substring`. - `trim_start(s)` - Remove leading whitespace from `s`. - `trim_start_match(s, substring)` - Remove prefix of `s` matching `substring`. - `trim_start_matches(s, substring)` - Repeatedly remove prefixes of `s` matching `substring`. #### Case Conversion - `capitalize(s)`1\.7.0 - Convert first character of `s` to uppercase and the rest to lowercase. - `kebabcase(s)`1\.7.0 - Convert `s` to `kebab-case`. - `lowercamelcase(s)`1\.7.0 - Convert `s` to `lowerCamelCase`. - `lowercase(s)` - Convert `s` to lowercase. - `shoutykebabcase(s)`1\.7.0 - Convert `s` to `SHOUTY-KEBAB-CASE`. - `shoutysnakecase(s)`1\.7.0 - Convert `s` to `SHOUTY_SNAKE_CASE`. - `snakecase(s)`1\.7.0 - Convert `s` to `snake_case`. - `titlecase(s)`1\.7.0 - Convert `s` to `Title Case`. - `uppercamelcase(s)`1\.7.0 - Convert `s` to `UpperCamelCase`. - `uppercase(s)` - Convert `s` to uppercase. #### Path Manipulation ##### Fallible - `absolute_path(path)` - Absolute path to relative `path` in the working directory. `absolute_path("./bar.txt")` in directory `/foo` is `/foo/bar.txt`. - `canonicalize(path)`1\.24.0 - Canonicalize `path` by resolving symlinks and removing `.`, `..`, and extra `/`s where possible. - `extension(path)` - Extension of `path`. `extension("/foo/bar.txt")` is `txt`. - `file_name(path)` - File name of `path` with any leading directory components removed. `file_name("/foo/bar.txt")` is `bar.txt`. - `file_stem(path)` - File name of `path` without extension. `file_stem("/foo/bar.txt")` is `bar`. - `parent_directory(path)` - Parent directory of `path`. `parent_directory("/foo/bar.txt")` is `/foo`. - `without_extension(path)` - `path` without extension. `without_extension("/foo/bar.txt")` is `/foo/bar`. These functions can fail, for example if a path does not have an extension, which will halt execution. ##### Infallible - `clean(path)` - Simplify `path` by removing extra path separators, intermediate `.` components, and `..` where possible. `clean("foo//bar")` is `foo/bar`, `clean("foo/..")` is `.`, `clean("foo/./bar")` is `foo/bar`. - `join(a, bā€¦)` - *This function uses `/` on Unix and `\` on Windows, which can be lead to unwanted behavior. The `/` operator, e.g., `a / b`, which always uses `/`, should be considered as a replacement unless `\`s are specifically desired on Windows.* Join path `a` with path `b`. `join("foo/bar", "baz")` is `foo/bar/baz`. Accepts two or more arguments. #### Filesystem Access - `path_exists(path)` - Returns the string `true` if the path points at an existing entity and the string `false` otherwise. Traverses symbolic links, and returns the string `false` if the path is inaccessible or points to a broken symlink. - `read(path)`1\.39.0 - Returns the content of file at `path` as string. ##### Error Reporting - `error(message)` - Abort execution and report error `message` to user. #### UUID and Hash Generation - `blake3(string)`1\.25.0 - Return [BLAKE3](https://github.com/BLAKE3-team/BLAKE3/) hash of `string` as hexadecimal string. - `blake3_file(path)`1\.25.0 - Return [BLAKE3](https://github.com/BLAKE3-team/BLAKE3/) hash of file at `path` as hexadecimal string. - `sha256(string)` - Return the SHA-256 hash of `string` as hexadecimal string. - `sha256_file(path)` - Return SHA-256 hash of file at `path` as hexadecimal string. - `uuid()` - Generate a random version 4 UUID. #### Random - `choose(n, alphabet)`1\.27.0 - Generate a string of `n` randomly selected characters from `alphabet`, which may not contain repeated characters. For example, `choose('64', HEX)` will generate a random 64-character lowercase hex string. #### Datetime - `datetime(format)`1\.30.0 - Return local time with `format`. - `datetime_utc(format)`1\.30.0 - Return UTC time with `format`. The arguments to `datetime` and `datetime_utc` are `strftime`\-style format strings, see the [`chrono` library docs](https://docs.rs/chrono/latest/chrono/format/strftime/index.html) for details. #### Semantic Versions - `semver_matches(version, requirement)`1\.16.0 - Check whether a [semantic `version`](https://semver.org/), e.g., `"0.1.0"` matches a `requirement`, e.g., `">=0.1.0"`, returning the string `"true"` if so and the string `"false"` otherwise. #### Style - `style(name)`1\.37.0 - Return a named terminal display attribute escape sequence used by `just`. Unlike terminal display attribute escape sequence constants, which contain standard colors and styles, `style(name)` returns an escape sequence used by `just` itself, and can be used to make recipe output match `just`'s own output. Recognized values for `name` are `'command'`, for echoed recipe lines, `error`, and `warning`. For example, to style an error message: ``` scary: @echo '{{ style("error") }}OH NO{{ NORMAL }}' ``` ##### User Directories These functions1\.23.0 return paths to user-specific directories for things like configuration, data, caches, executables, and the user's home directory. On Unix, these functions follow the [XDG Base Directory Specification](https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html). On MacOS and Windows, these functions return the system-specified user-specific directories. For example, `cache_directory()` returns `~/Library/Caches` on MacOS and `{FOLDERID_LocalAppData}` on Windows. See the [`dirs`](https://docs.rs/dirs/latest/dirs/index.html) crate for more details. - `cache_directory()` - The user-specific cache directory. - `config_directory()` - The user-specific configuration directory. - `config_local_directory()` - The local user-specific configuration directory. - `data_directory()` - The user-specific data directory. - `data_local_directory()` - The local user-specific data directory. - `executable_directory()` - The user-specific executable directory. - `home_directory()` - The user's home directory. If you would like to use XDG base directories on all platforms you can use the `env(ā€¦)` function with the appropriate environment variable and fallback, although note that the XDG specification requires ignoring non-absolute paths, so for full compatibility with spec-compliant applications, you would need to do: ``` xdg_config_dir := if env('XDG_CONFIG_HOME', '') =~ '^/' { env('XDG_CONFIG_HOME') } else { home_directory() / '.config' } ``` ### Constants A number of constants are predefined: | Name | Value | Value on Windows | |---|---|---| | `HEX`1\.27.0 | `"0123456789abcdef"` | | | `HEXLOWER`1\.27.0 | `"0123456789abcdef"` | | | `HEXUPPER`1\.27.0 | `"0123456789ABCDEF"` | | | `PATH_SEP`1\.41.0 | `"/"` | `"\"` | | `PATH_VAR_SEP`1\.41.0 | `":"` | `";"` | | `CLEAR`1\.37.0 | `"\ec"` | | | `NORMAL`1\.37.0 | `"\e[0m"` | | | `BOLD`1\.37.0 | `"\e[1m"` | | | `ITALIC`1\.37.0 | `"\e[3m"` | | | `UNDERLINE`1\.37.0 | `"\e[4m"` | | | `INVERT`1\.37.0 | `"\e[7m"` | | | `HIDE`1\.37.0 | `"\e[8m"` | | | `STRIKETHROUGH`1\.37.0 | `"\e[9m"` | | | `BLACK`1\.37.0 | `"\e[30m"` | | | `RED`1\.37.0 | `"\e[31m"` | | | `GREEN`1\.37.0 | `"\e[32m"` | | | `YELLOW`1\.37.0 | `"\e[33m"` | | | `BLUE`1\.37.0 | `"\e[34m"` | | | `MAGENTA`1\.37.0 | `"\e[35m"` | | | `CYAN`1\.37.0 | `"\e[36m"` | | | `WHITE`1\.37.0 | `"\e[37m"` | | | `BG_BLACK`1\.37.0 | `"\e[40m"` | | | `BG_RED`1\.37.0 | `"\e[41m"` | | | `BG_GREEN`1\.37.0 | `"\e[42m"` | | | `BG_YELLOW`1\.37.0 | `"\e[43m"` | | | `BG_BLUE`1\.37.0 | `"\e[44m"` | | | `BG_MAGENTA`1\.37.0 | `"\e[45m"` | | | `BG_CYAN`1\.37.0 | `"\e[46m"` | | | `BG_WHITE`1\.37.0 | `"\e[47m"` | | ``` @foo: echo {{HEX}} ``` ``` $ just foo 0123456789abcdef ``` Constants starting with `\e` are [ANSI escape sequences](https://en.wikipedia.org/wiki/ANSI_escape_code). `CLEAR` clears the screen, similar to the `clear` command. The rest are of the form `\e[Nm`, where `N` is an integer, and set terminal display attributes. Terminal display attribute escape sequences can be combined, for example text weight `BOLD`, text style `STRIKETHROUGH`, foreground color `CYAN`, and background color `BG_BLUE`. They should be followed by `NORMAL`, to reset the terminal back to normal. Escape sequences should be quoted, since `[` is treated as a special character by some shells. ``` @foo: echo '{{BOLD + STRIKETHROUGH + CYAN + BG_BLUE}}Hi!{{NORMAL}}' ``` ### Attributes Recipes, `mod` statements, and aliases may be annotated with attributes that change their behavior. | Name | Type | Description | |---|---|---| | `[arg(ARG, help="HELP")]`1\.46.0 | recipe | Print help string `HELP` for `ARG` in usage messages. | | `[arg(ARG, long="LONG")]`1\.46.0 | recipe | Require values of argument `ARG` to be passed as `--LONG` option. | | `[arg(ARG, pattern="PATTERN")]`1\.45.0 | recipe | Require values of argument `ARG` to match regular expression `PATTERN`. | | `[arg(ARG, short="S")]`1\.46.0 | recipe | Require values of argument `ARG` to be passed as short `-S` option. | | `[arg(ARG, value="VALUE")]`1\.46.0 | recipe | Makes option `ARG` a flag which does not take a value. | | `[confirm(PROMPT)]`1\.23.0 | recipe | Require confirmation prior to executing recipe with a custom prompt. | | `[confirm]`1\.17.0 | recipe | Require confirmation prior to executing recipe. | | `[default]`1\.43.0 | recipe | Use recipe as module's default recipe. | | `[doc(DOC)]`1\.27.0 | module, recipe | Set recipe or module's [documentation comment](https://github.com/casey/just#documentation-comments) to `DOC`. | | `[dragonfly]`1\.47.0 | recipe | Enable recipe on DragonFly BSD. | | `[env(ENV_VAR, VALUE)]` 1\.47.0 | recipe | Set environment variables for recipe. | | `[extension(EXT)]`1\.32.0 | recipe | Set shebang recipe script's file extension to `EXT`. `EXT` should include a period if one is desired. | | `[freebsd]`1\.47.0 | recipe | Enable recipe on FreeBSD. | | `[group(NAME)]`1\.27.0 | module, recipe | Put recipe or module in [group](https://github.com/casey/just#groups) `NAME`. | | `[linux]`1\.8.0 | recipe | Enable recipe on Linux. | | `[macos]`1\.8.0 | recipe | Enable recipe on MacOS. | | `[metadata(METADATA)]`1\.42.0 | recipe | Attach `METADATA` to recipe. | | `[netbsd]`1\.47.0 | recipe | Enable recipe on NetBSD. | | `[no-cd]`1\.9.0 | recipe | Don't change directory before executing recipe. | | `[no-exit-message]`1\.7.0 | recipe | Don't print an error message if recipe fails. | | `[no-quiet]`1\.23.0 | recipe | Override globally quiet recipes and always echo out the recipe. | | `[openbsd]`1\.38.0 | recipe | Enable recipe on OpenBSD. | | `[parallel]`1\.42.0 | recipe | Run this recipe's dependencies in parallel. | | `[positional-arguments]`1\.29.0 | recipe | Turn on [positional arguments](https://github.com/casey/just#positional-arguments) for this recipe. | | `[private]`1\.10.0 | alias, recipe | Make recipe, alias, or variable private. See [Private Recipes](https://github.com/casey/just#private-recipes). | | `[script(COMMAND)]`1\.32.0 | recipe | Execute recipe as a script interpreted by `COMMAND`. See [script recipes](https://github.com/casey/just#script-recipes) for more details. | | `[script]`1\.33.0 | recipe | Execute recipe as script. See [script recipes](https://github.com/casey/just#script-recipes) for more details. | | `[unix]`1\.8.0 | recipe | Enable recipe on Unixes. (Includes MacOS). | | `[windows]`1\.8.0 | recipe | Enable recipe on Windows. | | `[working-directory(PATH)]`1\.38.0 | recipe | Set recipe working directory. `PATH` may be relative or absolute. If relative, it is interpreted relative to the default working directory. | A recipe can have multiple attributes, either on multiple lines: ``` [no-cd] [private] foo: echo "foo" ``` Or separated by commas on a single line1\.14.0: ``` [no-cd, private] foo: echo "foo" ``` Attributes with a single argument may be written with a colon: ``` [group: 'bar'] foo: ``` #### Enabling and Disabling Recipes The `[linux]`, `[macos]`, `[unix]`, and `[windows]` attributes1\.8.0 are configuration attributes. By default, recipes are always enabled. A recipe with one or more configuration attributes will only be enabled when one or more of those configurations is active. This can be used to write `justfile`s that behave differently depending on which operating system they run on. The `run` recipe in this `justfile` will compile and run `main.c`, using a different C compiler and using the correct output binary name for that compiler depending on the operating system: ``` [unix] run: cc main.c ./a.out [windows] run: cl main.c main.exe ``` #### Disabling Changing Directory `just` normally executes recipes with the current directory set to the directory that contains the `justfile`. This can be disabled using the `[no-cd]` attribute1\.9.0. This can be used to create recipes which use paths relative to the invocation directory, or which operate on the current directory. For example, this `commit` recipe: ``` [no-cd] commit file: git add {{file}} git commit ``` Can be used with paths that are relative to the current directory, because `[no-cd]` prevents `just` from changing the current directory when executing `commit`. #### Requiring Confirmation for Recipes `just` normally executes all recipes unless there is an error. The `[confirm]` attribute1\.17.0 allows recipes require confirmation in the terminal prior to running. This can be overridden by passing `--yes` to `just`, which will automatically confirm any recipes marked by this attribute. Recipes dependent on a recipe that requires confirmation will not be run if the relied upon recipe is not confirmed, as well as recipes passed after any recipe that requires confirmation. ``` [confirm] delete-all: rm -rf * ``` #### Custom Confirmation Prompt The default confirmation prompt can be overridden with `[confirm(PROMPT)]`1\.23.0: ``` [confirm("Are you sure you want to delete everything?")] delete-everything: rm -rf * ``` #### Metadata Metadata in the form of lists of strings may be attached to recipes with the `[metadata(METADATA)]` attribute1\.42.0: ``` [metadata("hello", "goodbye")] foo: ``` Metadata can be read using `just --dump --dump-format json`. ### Groups Recipes and modules may be annotated with one or more group names: ``` [group('lint')] js-lint: echo 'Running JS linterā€¦' [group('rust recipes')] [group('lint')] rust-lint: echo 'Running Rust linterā€¦' [group('lint')] cpp-lint: echo 'Running C++ linterā€¦' # not in any group email-everyone: echo 'Sending mass emailā€¦' ``` Recipes are listed by group: ``` $ just --list Available recipes: email-everyone # not in any group [lint] cpp-lint js-lint rust-lint [rust recipes] rust-lint ``` `just --list --unsorted` prints recipes in their justfile order within each group: ``` $ just --list --unsorted Available recipes: (no group) email-everyone # not in any group [lint] js-lint rust-lint cpp-lint [rust recipes] rust-lint ``` Groups can be listed with `--groups`: ``` $ just --groups Recipe groups: lint rust recipes ``` Use `just --groups --unsorted` to print groups in their justfile order. ### Command Evaluation Using Backticks Backticks can be used to store the result of commands: ``` localhost := `dumpinterfaces | cut -d: -f2 | sed 's/\/.*//' | sed 's/ //g'` serve: ./serve {{localhost}} 8080 ``` Indented backticks, delimited by three backticks, are de-indented in the same manner as indented strings: ``` # This backtick evaluates the command `echo foo\necho bar\n`, which produces the value `foo\nbar\n`. stuff := ``` echo foo echo bar ``` ``` See the [Strings](https://github.com/casey/just#strings) section for details on unindenting. Backticks may not start with `#!`. This syntax is reserved for a future upgrade. The [`shell(ā€¦)` function](https://github.com/casey/just#external-commands) provides a more general mechanism to invoke external commands, including the ability to execute the contents of a variable as a command, and to pass arguments to a command. ### Conditional Expressions `if`/`else` expressions evaluate different branches depending on if two expressions evaluate to the same value: ``` foo := if "2" == "2" { "Good!" } else { "1984" } bar: @echo "{{foo}}" ``` ``` $ just bar Good! ``` It is also possible to test for inequality: ``` foo := if "hello" != "goodbye" { "xyz" } else { "abc" } bar: @echo {{foo}} ``` ``` $ just bar xyz ``` And match against regular expressions: ``` foo := if "hello" =~ 'hel+o' { "match" } else { "mismatch" } bar: @echo {{foo}} ``` ``` $ just bar match ``` Regular expressions are provided by the [regex crate](https://github.com/rust-lang/regex), whose syntax is documented on [docs.rs](https://docs.rs/regex/1.5.4/regex/#syntax). Since regular expressions commonly use backslash escape sequences, consider using single-quoted string literals, which will pass slashes to the regex parser unmolested. Conditional expressions short-circuit, which means they only evaluate one of their branches. This can be used to make sure that backtick expressions don't run when they shouldn't. ``` foo := if env_var("RELEASE") == "true" { `get-something-from-release-database` } else { "dummy-value" } ``` Conditionals can be used inside of recipes: ``` bar foo: echo {{ if foo == "bar" { "hello" } else { "goodbye" } }} ``` Multiple conditionals can be chained: ``` foo := if "hello" == "goodbye" { "xyz" } else if "a" == "a" { "abc" } else { "123" } bar: @echo {{foo}} ``` ``` $ just bar abc ``` ### Stopping execution with error Execution can be halted with the `error` function. For example: ``` foo := if "hello" == "goodbye" { "xyz" } else if "a" == "b" { "abc" } else { error("123") } ``` Which produce the following error when run: ``` error: Call to function `error` failed: 123 | 16 | error("123") ``` ### Setting Variables from the Command Line Variables can be overridden from the command line. ``` os := "linux" test: build ./test --test {{os}} build: ./build {{os}} ``` ``` $ just ./build linux ./test --test linux ``` Any number of arguments of the form `NAME=VALUE` can be passed before recipes: ``` $ just os=plan9 ./build plan9 ./test --test plan9 ``` Or you can use the `--set` flag: ``` $ just --set os bsd ./build bsd ./test --test bsd ``` Variables in submodules can be overridden using the `::`\-separated path to the variable. A variable named `bar` in a submodule named `foo` may be overridden with `foo::bar=VALUE` or `--set foo::bar VALUE`. ### Getting and Setting Environment Variables #### Exporting `just` Variables Assignments prefixed with the `export` keyword will be exported to recipes as environment variables: ``` export RUST_BACKTRACE := "1" test: # will print a stack trace if it crashes cargo test ``` Parameters prefixed with a `$` will be exported as environment variables: ``` test $RUST_BACKTRACE="1": # will print a stack trace if it crashes cargo test ``` You can also use the `[env(NAME, VALUE)]` attribute to export environment variables to a specific recipe: ``` [env("RUST_BACKTRACE", "1")] test: # will print a stack trace if it crashes cargo test ``` Exported variables and parameters are not exported to backticks in the same scope. ``` export WORLD := "world" # This backtick will fail with "WORLD: unbound variable" BAR := `echo hello $WORLD` ``` ``` # Running `just a foo` will fail with "A: unbound variable" a $A $B=`echo $A`: echo $A $B ``` When [export](https://github.com/casey/just#export) is set, all `just` variables are exported as environment variables. #### Unexporting Environment Variables Environment variables can be unexported with the `unexport keyword`1\.29.0: ``` unexport FOO @foo: echo $FOO ``` ``` $ export FOO=bar $ just foo sh: FOO: unbound variable ``` #### Getting Environment Variables from the environment Environment variables from the environment are passed automatically to the recipes. ``` print_home_folder: echo "HOME is: '${HOME}'" ``` ``` $ just HOME is '/home/myuser' ``` #### Setting `just` Variables from Environment Variables Environment variables can be propagated to `just` variables using the `env()` function. See [environment-variables](https://github.com/casey/just#environment-variables). ### Recipe Parameters Recipes may have parameters. Here recipe `build` has a parameter called `target`: ``` build target: @echo 'Building {{target}}ā€¦' cd {{target}} && make ``` To pass arguments on the command line, put them after the recipe name: ``` $ just build my-awesome-project Building my-awesome-projectā€¦ cd my-awesome-project && make ``` To pass arguments to a dependency, put the dependency in parentheses along with the arguments: ``` default: (build "main") build target: @echo 'Building {{target}}ā€¦' cd {{target}} && make ``` Variables can also be passed as arguments to dependencies: ``` target := "main" _build version: @echo 'Building {{version}}ā€¦' cd {{version}} && make build: (_build target) ``` A command's arguments can be passed to dependency by putting the dependency in parentheses along with the arguments: ``` build target: @echo "Building {{target}}ā€¦" push target: (build target) @echo 'Pushing {{target}}ā€¦' ``` Parameters may have default values: ``` default := 'all' test target tests=default: @echo 'Testing {{target}}:{{tests}}ā€¦' ./test --tests {{tests}} {{target}} ``` Parameters with default values may be omitted: ``` $ just test server Testing server:allā€¦ ./test --tests all server ``` Or supplied: ``` $ just test server unit Testing server:unitā€¦ ./test --tests unit server ``` Default values may be arbitrary expressions, but expressions containing the `+`, `&&`, `||`, or `/` operators must be parenthesized: ``` arch := "wasm" test triple=(arch + "-unknown-unknown") input=(arch / "input.dat"): ./test {{triple}} ``` The last parameter of a recipe may be variadic, indicated with either a `+` or a `*` before the argument name: ``` backup +FILES: scp {{FILES}} me@server.com: ``` Variadic parameters prefixed with `+` accept *one or more* arguments and expand to a string containing those arguments separated by spaces: ``` $ just backup FAQ.md GRAMMAR.md scp FAQ.md GRAMMAR.md me@server.com: FAQ.md 100% 1831 1.8KB/s 00:00 GRAMMAR.md 100% 1666 1.6KB/s 00:00 ``` Variadic parameters prefixed with `*` accept *zero or more* arguments and expand to a string containing those arguments separated by spaces, or an empty string if no arguments are present: ``` commit MESSAGE *FLAGS: git commit {{FLAGS}} -m "{{MESSAGE}}" ``` Variadic parameters can be assigned default values. These are overridden by arguments passed on the command line: ``` test +FLAGS='-q': cargo test {{FLAGS}} ``` `{{ā€¦}}` substitutions may need to be quoted if they contain spaces. For example, if you have the following recipe: ``` search QUERY: lynx https://www.google.com/?q={{QUERY}} ``` And you type: ``` $ just search "cat toupee" ``` `just` will run the command `lynx https://www.google.com/?q=cat toupee`, which will get parsed by `sh` as `lynx`, `https://www.google.com/?q=cat`, and `toupee`, and not the intended `lynx` and `https://www.google.com/?q=cat toupee`. You can fix this by adding quotes: ``` search QUERY: lynx 'https://www.google.com/?q={{QUERY}}' ``` Parameters prefixed with a `$` will be exported as environment variables: ``` foo $bar: echo $bar ``` Parameters may be constrained to match regular expression patterns using the `[arg("name", pattern="pattern")]` attribute1\.45.0: ``` [arg('n', pattern='\d+')] double n: echo $(({{n}} * 2)) ``` A leading `^` and trailing `$` are added to the pattern, so it must match the entire argument value. You may constrain the pattern to a number of alternatives using the `|` operator: ``` [arg('flag', pattern='--help|--version')] info flag: just {{flag}} ``` Regular expressions are provided by the [Rust `regex` crate](https://docs.rs/regex/latest/regex/). See the [syntax documentation](https://docs.rs/regex/latest/regex/#syntax) for usage examples. Usage information for a recipe may be printed with the `--usage` subcommand1\.46.0: ``` $ just --usage foo Usage: just foo [OPTIONS] bar Arguments: bar ``` Help strings may be added to arguments using the `[arg(ARG, help=HELP)]` attribute: ``` [arg("bar", help="hello")] foo bar: ``` ``` $ just --usage foo Usage: just foo bar Arguments: bar hello ``` #### Recipe Flags and Options Recipe parameters are positional by default. In this `justfile`: ``` @foo bar: echo bar={{bar}} ``` The parameter `bar` is positional: ``` $ just foo hello bar=hello ``` The `[arg(ARG, long=OPTION)]`1\.46.0 attribute can be used to make a parameter a long option. In this `justfile`: ``` [arg("bar", long="bar")] foo bar: ``` The parameter `bar` is given with the `--bar` option: ``` $ just foo --bar hello bar=hello ``` Options may also be passed with `--name=value` syntax: ``` $ just foo --bar=hello bar=hello ``` The value of `long` can be omitted, in which case the option defaults to the name of the parameter: ``` [arg("bar", long)] foo bar: ``` The `[arg(ARG, short=OPTION)]`1\.46.0 attribute can be used to make a parameter a short option. In this `justfile`: ``` [arg("bar", short="b")] foo bar: ``` The parameter `bar` is given with the `-b` option: ``` $ just foo -b hello bar=hello ``` If a parameter has both a long and short option, it may be passed using either. Variadic `*` and `+` parameters cannot be options. The `[arg(ARG, value=VALUE, ā€¦)]`1\.46.0 attribute can be used with `long` or `short` to make a parameter a flag which does not take a value. In this `justfile`: ``` [arg("bar", long="bar", value="hello")] foo bar: ``` The parameter `bar` is given with the `--bar` option, but does not take a value, and instead takes the value given in the `[arg]` attribute: ``` $ just foo --bar bar=hello ``` This is useful for unconditionally requiring a flag like `--force` on dangerous commands. A flag is optional if its parameter has a default: ``` [arg("bar", long="bar", value="hello")] foo bar="goodbye": ``` Causing it to receive the default when not passed in the invocation: ``` $ just foo bar=goodbye ``` ### Dependencies Dependencies run before recipes that depend on them: ``` a: b @echo A b: @echo B ``` ``` $ just a B A ``` In a given invocation of `just`, a recipe with the same arguments will only run once, regardless of how many times it appears in the command-line invocation, or how many times it appears as a dependency: ``` a: @echo A b: a @echo B c: a @echo C ``` ``` $ just a a a a a A $ just b c A B C ``` Multiple recipes may depend on a recipe that performs some kind of setup, and when those recipes run, that setup will only be performed once: ``` build: cc main.c test-foo: build ./a.out --test foo test-bar: build ./a.out --test bar ``` ``` $ just test-foo test-bar cc main.c ./a.out --test foo ./a.out --test bar ``` Recipes in a given run are only skipped when they receive the same arguments: ``` build: cc main.c test TEST: build ./a.out --test {{TEST}} ``` ``` $ just test foo test bar cc main.c ./a.out --test foo ./a.out --test bar ``` #### Running Recipes at the End of a Recipe Normal dependencies of a recipes always run before a recipe starts. That is to say, the dependee always runs before the depender. These dependencies are called "prior dependencies". A recipe can also have subsequent dependencies, which run immediately after the recipe and are introduced with an `&&`: ``` a: echo 'A!' b: a && c d echo 'B!' c: echo 'C!' d: echo 'D!' ``` ā€¦running *b* prints: ``` $ just b echo 'A!' A! echo 'B!' B! echo 'C!' C! echo 'D!' D! ``` #### Running Recipes in the Middle of a Recipe `just` doesn't support running recipes in the middle of another recipe, but you can call `just` recursively in the middle of a recipe. Given the following `justfile`: ``` a: echo 'A!' b: a echo 'B start!' just c echo 'B end!' c: echo 'C!' ``` ā€¦running *b* prints: ``` $ just b echo 'A!' A! echo 'B start!' B start! echo 'C!' C! echo 'B end!' B end! ``` This has limitations, since recipe `c` is run with an entirely new invocation of `just`: Assignments will be recalculated, dependencies might run twice, and command line arguments will not be propagated to the child `just` process. ### Shebang Recipes Recipes that start with `#!` are called shebang recipes, and are executed by saving the recipe body to a file and running it. This lets you write recipes in different languages: ``` polyglot: python js perl sh ruby nu python: #!/usr/bin/env python3 print('Hello from python!') js: #!/usr/bin/env node console.log('Greetings from JavaScript!') perl: #!/usr/bin/env perl print "Larry Wall says Hi!\n"; sh: #!/usr/bin/env sh hello='Yo' echo "$hello from a shell script!" nu: #!/usr/bin/env nu let hello = 'Hola' echo $"($hello) from a nushell script!" ruby: #!/usr/bin/env ruby puts "Hello from ruby!" ``` ``` $ just polyglot Hello from python! Greetings from JavaScript! Larry Wall says Hi! Yo from a shell script! Hola from a nushell script! Hello from ruby! ``` On Unix-like operating systems, including Linux and MacOS, shebang recipes are executed by saving the recipe body to a file in a temporary directory, marking the file as executable, and executing it. The OS then parses the shebang line into a command line and invokes it, including the path to the file. For example, if a recipe starts with `#!/usr/bin/env bash`, the final command that the OS runs will be something like `/usr/bin/env bash /tmp/PATH_TO_SAVED_RECIPE_BODY`. Shebang line splitting is operating system dependent. When passing a command with arguments, you may need to tell `env` to split them explicitly by using the `-S` flag: ``` run: #!/usr/bin/env -S bash -x ls ``` Windows does not support shebang lines. On Windows, `just` splits the shebang line into a command and arguments, saves the recipe body to a file, and invokes the split command and arguments, adding the path to the saved recipe body as the final argument. For example, on Windows, if a recipe starts with `#! py`, the final command the OS runs will be something like `py C:\Temp\PATH_TO_SAVED_RECIPE_BODY`. ### Script Recipes Recipes with a `[script(COMMAND)]`1\.32.0 attribute are run as scripts interpreted by `COMMAND`. This avoids some of the issues with shebang recipes, such as the use of `cygpath` on Windows, the need to use `/usr/bin/env`, inconsistencies in shebang line splitting across Unix OSs, and requiring a temporary directory from which files can be executed. Recipes with an empty `[script]` attribute are executed with the value of `set script-interpreter := [ā€¦]`1\.33.0, defaulting to `sh -eu`, and *not* the value of `set shell`. The body of the recipe is evaluated, written to disk in the temporary directory, and run by passing its path as an argument to `COMMAND`. ### Script and Shebang Recipe Temporary Files Both script and shebang recipes write the recipe body to a temporary file for execution. Script recipes execute that file by passing it to a command, while shebang recipes execute the file directly. Shebang recipe execution will fail if the filesystem containing the temporary file is mounted with `noexec` or is otherwise non-executable. The directory that `just` writes temporary files to may be configured in a number of ways, from highest to lowest precedence: - Globally with the `--tempdir` command-line option or the `JUST_TEMPDIR` environment variable1\.41.0. - On a per-module basis with the `tempdir` setting. - Globally on Linux with the `XDG_RUNTIME_DIR` environment variable. - Falling back to the directory returned by [std::env::temp\_dir](https://doc.rust-lang.org/std/env/fn.temp_dir.html). ### Python Recipes with `uv` [`uv`](https://github.com/astral-sh/uv) is an excellent cross-platform python project manager, written in Rust. Using the `[script]` attribute and `script-interpreter` setting, `just` can easily be configured to run Python recipes with `uv`: ``` set script-interpreter := ['uv', 'run', '--script'] [script] hello: print("Hello from Python!") [script] goodbye: # /// script # requires-python = ">=3.11" # dependencies=["sh"] # /// import sh print(sh.echo("Goodbye from Python!"), end='') ``` Of course, a shebang also works: ``` hello: #!/usr/bin/env -S uv run --script print("Hello from Python!") ``` ### Safer Bash Shebang Recipes If you're writing a `bash` shebang recipe, consider adding `set -euxo pipefail`: ``` foo: #!/usr/bin/env bash set -euxo pipefail hello='Yo' echo "$hello from Bash!" ``` It isn't strictly necessary, but `set -euxo pipefail` turns on a few useful features that make `bash` shebang recipes behave more like normal, linewise `just` recipe: - `set -e` makes `bash` exit if a command fails. - `set -u` makes `bash` exit if a variable is undefined. - `set -x` makes `bash` print each script line before it's run. - `set -o pipefail` makes `bash` exit if a command in a pipeline fails. This is `bash`\-specific, so isn't turned on in normal linewise `just` recipes. Together, these avoid a lot of shell scripting gotchas. #### Shebang Recipe Execution on Windows On Windows, shebang interpreter paths containing a `/` are translated from Unix-style paths to Windows-style paths using `cygpath`, a utility that ships with [Cygwin](http://www.cygwin.com/). For example, to execute this recipe on Windows: ``` echo: #!/bin/sh echo "Hello!" ``` The interpreter path `/bin/sh` will be translated to a Windows-style path using `cygpath` before being executed. If the interpreter path does not contain a `/` it will be executed without being translated. This is useful if `cygpath` is not available, or you wish to pass a Windows-style path to the interpreter. ### Setting Variables in a Recipe Recipe lines are interpreted by the shell, not `just`, so it's not possible to set `just` variables in the middle of a recipe: ``` foo: x := "hello" # This doesn't work! echo {{x}} ``` It is possible to use shell variables, but there's another problem. Every recipe line is run by a new shell instance, so variables set in one line won't be set in the next: ``` foo: x=hello && echo $x # This works! y=bye echo $y # This doesn't, `y` is undefined here! ``` The best way to work around this is to use a shebang recipe. Shebang recipe bodies are extracted and run as scripts, so a single shell instance will run the whole thing: ``` foo: #!/usr/bin/env bash set -euxo pipefail x=hello echo $x ``` ### Sharing Environment Variables Between Recipes Each line of each recipe is executed by a fresh shell, so it is not possible to share environment variables between recipes. #### Using Python Virtual Environments Some tools, like [Python's venv](https://docs.python.org/3/library/venv.html), require loading environment variables in order to work, making them challenging to use with `just`. As a workaround, you can execute the virtual environment binaries directly: ``` venv: [ -d foo ] || python3 -m venv foo run: venv ./foo/bin/python3 main.py ``` ### Changing the Working Directory in a Recipe Each recipe line is executed by a new shell, so if you change the working directory on one line, it won't have an effect on later lines: ``` foo: pwd # This `pwd` will print the same directoryā€¦ cd bar pwd # ā€¦as this `pwd`! ``` There are a couple ways around this. One is to call `cd` on the same line as the command you want to run: ``` foo: cd bar && pwd ``` The other is to use a shebang recipe. Shebang recipe bodies are extracted and run as scripts, so a single shell instance will run the whole thing, and thus a `cd` on one line will affect later lines, just like a shell script: ``` foo: #!/usr/bin/env bash set -euxo pipefail cd bar pwd ``` ### Indentation Recipe lines can be indented with spaces or tabs, but not a mix of both. All of a recipe's lines must have the same type of indentation, but different recipes in the same `justfile` may use different indentation. Each recipe must be indented at least one level from the `recipe-name` but after that may be further indented. Here's a justfile with a recipe indented with spaces, represented as `Ā·`, and tabs, represented as `ā†’`. ``` set windows-shell := ["pwsh", "-NoLogo", "-NoProfileLoadTime", "-Command"] set ignore-comments list-space directory: Ā·Ā·#!pwsh Ā·Ā·foreach ($item in $(Get-ChildItem {{directory}} )) { Ā·Ā·Ā·Ā·echo $item.Name Ā·Ā·} Ā·Ā·echo "" # indentation nesting works even when newlines are escaped list-tab directory: ā†’ @foreach ($item in $(Get-ChildItem {{directory}} )) { \ ā†’ ā†’ echo $item.Name \ ā†’ } ā†’ @echo "" ``` ``` PS > just list-space ~ Desktop Documents Downloads PS > just list-tab ~ Desktop Documents Downloads ``` ### Multi-Line Constructs Recipes without an initial shebang are evaluated and run line-by-line, which means that multi-line constructs probably won't do what you want. For example, with the following `justfile`: ``` conditional: if true; then echo 'True!' fi ``` The extra leading whitespace before the second line of the `conditional` recipe will produce a parse error: ``` $ just conditional error: Recipe line has extra leading whitespace | 3 | echo 'True!' | ^^^^^^^^^^^^^^^^ ``` To work around this, you can write conditionals on one line, escape newlines with slashes, or add a shebang to your recipe. Some examples of multi-line constructs are provided for reference. #### `if` statements ``` conditional: if true; then echo 'True!'; fi ``` ``` conditional: if true; then \ echo 'True!'; \ fi ``` ``` conditional: #!/usr/bin/env sh if true; then echo 'True!' fi ``` #### `for` loops ``` for: for file in `ls .`; do echo $file; done ``` ``` for: for file in `ls .`; do \ echo $file; \ done ``` ``` for: #!/usr/bin/env sh for file in `ls .`; do echo $file done ``` #### `while` loops ``` while: while `server-is-dead`; do ping -c 1 server; done ``` ``` while: while `server-is-dead`; do \ ping -c 1 server; \ done ``` ``` while: #!/usr/bin/env sh while `server-is-dead`; do ping -c 1 server done ``` #### Outside Recipe Bodies Parenthesized expressions can span multiple lines: ``` abc := ('a' + 'b' + 'c') abc2 := ( 'a' + 'b' + 'c' ) foo param=('foo' + 'bar' ): echo {{param}} bar: (foo 'Foo' ) echo 'Bar!' ``` Lines ending with a backslash continue on to the next line as if the lines were joined by whitespace1\.15.0: ``` a := 'foo' + \ 'bar' foo param1 \ param2='foo' \ *varparam='': dep1 \ (dep2 'foo') echo {{param1}} {{param2}} {{varparam}} dep1: \ # this comment is not part of the recipe body echo 'dep1' dep2 \ param: echo 'Dependency with parameter {{param}}' ``` Backslash line continuations can also be used in interpolations. The line following the backslash must be indented. ``` recipe: echo '{{ \ "This interpolation " + \ "has a lot of text." \ }}' echo 'back to recipe body' ``` ### Command-line Options `just` supports a number of useful command-line options for listing, dumping, and debugging recipes and variables: ``` $ just --list Available recipes: js perl polyglot python ruby $ just --show perl perl: #!/usr/bin/env perl print "Larry Wall says Hi!\n"; $ just --show polyglot polyglot: python js perl sh ruby ``` #### Setting Command-line Options with Environment Variables Some command-line options can be set with environment variables For example, unstable features can be enabled either with the `--unstable` flag: ``` $ just --unstable ``` Or by setting the `JUST_UNSTABLE` environment variable: ``` $ export JUST_UNSTABLE=1 $ just ``` Since environment variables are inherited by child processes, command-line options set with environment variables are inherited by recursive invocations of `just`, where as command line options set with arguments are not. Consult `just --help` for which options can be set with environment variables. ### Private Recipes Recipes and aliases whose name starts with a `_` are omitted from `just --list`: ``` test: _test-helper ./bin/test _test-helper: ./bin/super-secret-test-helper-stuff ``` ``` $ just --list Available recipes: test ``` And from `just --summary`: ``` $ just --summary test ``` The `[private]` attribute1\.10.0 may also be used to hide recipes or aliases without needing to change the name: ``` [private] foo: [private] alias b := bar bar: ``` ``` $ just --list Available recipes: bar ``` This is useful for helper recipes which are only meant to be used as dependencies of other recipes. ### Quiet Recipes A recipe name may be prefixed with `@` to invert the meaning of `@` before each line: ``` @quiet: echo hello echo goodbye @# all done! ``` Now only the lines starting with `@` will be echoed: ``` $ just quiet hello goodbye # all done! ``` All recipes in a Justfile can be made quiet with `set quiet`: ``` set quiet foo: echo "This is quiet" @foo2: echo "This is also quiet" ``` The `[no-quiet]` attribute overrides this setting: ``` set quiet foo: echo "This is quiet" [no-quiet] foo2: echo "This is not quiet" ``` Shebang recipes are quiet by default: ``` foo: #!/usr/bin/env bash echo 'Foo!' ``` ``` $ just foo Foo! ``` Adding `@` to a shebang recipe name makes `just` print the recipe before executing it: ``` @bar: #!/usr/bin/env bash echo 'Bar!' ``` ``` $ just bar #!/usr/bin/env bash echo 'Bar!' Bar! ``` `just` normally prints error messages when a recipe line fails. These error messages can be suppressed using the `[no-exit-message]`1\.7.0 attribute. You may find this especially useful with a recipe that wraps a tool: ``` git *args: @git {{args}} ``` ``` $ just git status fatal: not a git repository (or any of the parent directories): .git error: Recipe `git` failed on line 2 with exit code 128 ``` Add the attribute to suppress the exit error message when the tool exits with a non-zero code: ``` [no-exit-message] git *args: @git {{args}} ``` ``` $ just git status fatal: not a git repository (or any of the parent directories): .git ``` ### Selecting Recipes to Run With an Interactive Chooser The `--choose` subcommand makes `just` invoke a chooser to select which recipes to run. Choosers should read lines containing recipe names from standard input and print one or more of those names separated by spaces to standard output. Because there is currently no way to run a recipe that requires arguments with `--choose`, such recipes will not be given to the chooser. Private recipes and aliases are also skipped. The chooser can be overridden with the `--chooser` flag. If `--chooser` is not given, then `just` first checks if `$JUST_CHOOSER` is set. If it isn't, then the chooser defaults to `fzf`, a popular fuzzy finder. Arguments can be included in the chooser, i.e. `fzf --exact`. The chooser is invoked in the same way as recipe lines. For example, if the chooser is `fzf`, it will be invoked with `sh -cu 'fzf'`, and if the shell, or the shell arguments are overridden, the chooser invocation will respect those overrides. If you'd like `just` to default to selecting recipes with a chooser, you can use this as your default recipe: ``` default: @just --choose ``` ### Invoking `justfile`s in Other Directories If the first argument passed to `just` contains a `/`, then the following occurs: 1. The argument is split at the last `/`. 2. The part before the last `/` is treated as a directory. `just` will start its search for the `justfile` there, instead of in the current directory. 3. The part after the last slash is treated as a normal argument, or ignored if it is empty. This may seem a little strange, but it's useful if you wish to run a command in a `justfile` that is in a subdirectory. For example, if you are in a directory which contains a subdirectory named `foo`, which contains a `justfile` with the recipe `build`, which is also the default recipe, the following are all equivalent: ``` $ (cd foo && just build) $ just foo/build $ just foo/ ``` Additional recipes after the first are sought in the same `justfile`. For example, the following are both equivalent: ``` $ just foo/a b $ (cd foo && just a b) ``` And will both invoke recipes `a` and `b` in `foo/justfile`. ### Imports One `justfile` can include the contents of another using `import` statements. If you have the following `justfile`: ``` import 'foo/bar.just' a: b @echo A ``` And the following text in `foo/bar.just`: ``` b: @echo B ``` `foo/bar.just` will be included in `justfile` and recipe `b` will be defined: ``` $ just b B $ just a B A ``` The `import` path can be absolute or relative to the location of the justfile containing it. A leading `~/` in the import path is replaced with the current users home directory. Justfiles are insensitive to order, so included files can reference variables and recipes defined after the `import` statement. Imported files can themselves contain `import`s, which are processed recursively. `allow-duplicate-recipes` and `allow-duplicate-variables` allow duplicate recipes and variables, respectively, to override each other, instead of producing an error. Within a module, later definitions override earlier definitions: ``` set allow-duplicate-recipes foo: foo: echo 'yes' ``` When `import`s are involved, things unfortunately get much more complicated and hard to explain. Shallower definitions always override deeper definitions, so recipes at the top level will override recipes in imports, and recipes in an import will override recipes in an import which itself imports those recipes. When two duplicate definitions are imported and are at the same depth, the one from the earlier import will override the one from the later import. This is because `just` uses a stack when processing imports, pushing imports onto the stack in source-order, and always processing the top of the stack next, so earlier imports are actually handled later by the compiler. This is definitely a bug, but since `just` has very strong backwards compatibility guarantees and we take enormous pains not to break anyone's `justfile`, we have created issue \#2540 to discuss whether or not we can actually fix it. Imports may be made optional by putting a `?` after the `import` keyword: ``` import? 'foo/bar.just' ``` Importing the same source file multiple times is not an error1\.37.0. This allows importing multiple justfiles, for example `foo.just` and `bar.just`, which both import a third justfile containing shared recipes, for example `baz.just`, without the duplicate import of `baz.just` being an error: ``` # justfile import 'foo.just' import 'bar.just' ``` ``` # foo.just import 'baz.just' foo: baz ``` ``` # bar.just import 'baz.just' bar: baz ``` ``` # baz baz: ``` ### Modules A `justfile` can declare modules using `mod` statements1\.19.0. `mod` statements were stabilized in `just`1\.31.0. If you have the following `justfile`: ``` mod bar a: @echo A ``` And the following text in `bar.just`: ``` b: @echo B ``` `bar.just` will be included in `justfile` as a submodule. Recipes, aliases, and variables defined in one submodule cannot be used in another, and each module uses its own settings. Recipes in submodules can be invoked as subcommands: ``` $ just bar b B ``` Or with path syntax: ``` $ just bar::b B ``` If a module is named `foo`, just will search for the module file in `foo.just`, `foo/mod.just`, `foo/justfile`, and `foo/.justfile`. In the latter two cases, the module file may have any capitalization. Module statements may be of the form: ``` mod foo 'PATH' ``` Which loads the module's source file from `PATH`, instead of from the usual locations. A leading `~/` in `PATH` is replaced with the current user's home directory. `PATH` may point to the module source file itself, or to a directory containing the module source file with the name `mod.just`, `justfile`, or `.justfile`. In the latter two cases, the module file may have any capitalization. Environment files are only loaded for the root justfile, and loaded environment variables are available in submodules. Settings in submodules that affect environment file loading are ignored. Recipes in submodules without the `[no-cd]` attribute run with the working directory set to the directory containing the submodule source file. `justfile()` and `justfile_directory()` always return the path to the root justfile and the directory that contains it, even when called from submodule recipes. Modules may be made optional by putting a `?` after the `mod` keyword: ``` mod? foo ``` Missing source files for optional modules do not produce an error. Optional modules with no source file do not conflict, so you can have multiple mod statements with the same name, but with different source file paths, as long as at most one source file exists: ``` mod? foo 'bar.just' mod? foo 'baz.just' ``` Modules may be given doc comments which appear in `--list` output1\.30.0: ``` # foo is a great module! mod foo ``` ``` $ just --list Available recipes: foo ... # foo is a great module! ``` Modules are still missing a lot of features, for example, the ability to refer to variables in other modules. See the [module improvement tracking issue](https://github.com/casey/just/issues/2252) for more information. ### Hiding `justfile`s `just` looks for `justfile`s named `justfile` and `.justfile`, which can be used to keep a `justfile` hidden. ### Just Scripts By adding a shebang line to the top of a `justfile` and making it executable, `just` can be used as an interpreter for scripts: ``` $ cat > script <<EOF #!/usr/bin/env just --justfile foo: echo foo EOF $ chmod +x script $ ./script foo echo foo foo ``` When a script with a shebang is executed, the system supplies the path to the script as an argument to the command in the shebang. So, with a shebang of `#!/usr/bin/env just --justfile`, the command will be `/usr/bin/env just --justfile PATH_TO_SCRIPT`. With the above shebang, `just` will change its working directory to the location of the script. If you'd rather leave the working directory unchanged, use `#!/usr/bin/env just --working-directory . --justfile`. Note: Shebang line splitting is not consistent across operating systems. The previous examples have only been tested on macOS. On Linux, you may need to pass the `-S` flag to `env`: ``` #!/usr/bin/env -S just --justfile default: echo foo ``` ### Formatting and dumping `justfile`s Each `justfile` has a canonical formatting with respect to whitespace and newlines. You can overwrite the current justfile with a canonically-formatted version using the currently-unstable `--fmt` flag: ``` $ cat justfile # A lot of blank lines some-recipe: echo "foo" $ just --fmt --unstable $ cat justfile # A lot of blank lines some-recipe: echo "foo" ``` Invoking `just --fmt --check --unstable` runs `--fmt` in check mode. Instead of overwriting the `justfile`, `just` will exit with an exit code of 0 if it is formatted correctly, and will exit with 1 and print a diff if it is not. You can use the `--dump` command to output a formatted version of the `justfile` to stdout: ``` $ just --dump > formatted-justfile ``` The `--dump` command can be used with `--dump-format json` to print a JSON representation of a `justfile`. ### Fallback to parent `justfile`s If a recipe is not found in a `justfile` and the `fallback` setting is set, `just` will look for `justfile`s in the parent directory and up, until it reaches the root directory. `just` will stop after it reaches a `justfile` in which the `fallback` setting is `false` or unset. As an example, suppose the current directory contains this `justfile`: ``` set fallback foo: echo foo ``` And the parent directory contains this `justfile`: ``` bar: echo bar ``` ``` $ just bar Trying ../justfile echo bar bar ``` ### Avoiding Argument Splitting Given this `justfile`: ``` foo argument: touch {{argument}} ``` The following command will create two files, `some` and `argument.txt`: ``` $ just foo "some argument.txt" ``` The user's shell will parse `"some argument.txt"` as a single argument, but when `just` replaces `touch {{argument}}` with `touch some argument.txt`, the quotes are not preserved, and `touch` will receive two arguments. There are a few ways to avoid this: quoting, positional arguments, and exported arguments. #### Quoting Quotes can be added around the `{{argument}}` interpolation: ``` foo argument: touch '{{argument}}' ``` This preserves `just`'s ability to catch variable name typos before running, for example if you were to write `{{argument}}`, but will not do what you want if the value of `argument` contains single quotes. #### Positional Arguments The `positional-arguments` setting causes all arguments to be passed as positional arguments, allowing them to be accessed with `$1`, `$2`, ā€¦, and `$@`, which can be then double-quoted to avoid further splitting by the shell: ``` set positional-arguments foo argument: touch "$1" ``` This defeats `just`'s ability to catch typos, for example if you type `$2` instead of `$1`, but works for all possible values of `argument`, including those with double quotes. #### Exported Arguments All arguments are exported when the `export` setting is set: ``` set export foo argument: touch "$argument" ``` Or individual arguments may be exported by prefixing them with `$`: ``` foo $argument: touch "$argument" ``` This defeats `just`'s ability to catch typos, for example if you type `$argument`, but works for all possible values of `argument`, including those with double quotes. ### Configuring the Shell There are a number of ways to configure the shell for linewise recipes, which are the default when a recipe does not start with a `#!` shebang. Their precedence, from highest to lowest, is: 1. The `--shell` and `--shell-arg` command line options. Passing either of these will cause `just` to ignore any settings in the current justfile. 2. `set windows-shell := [...]` 3. `set windows-powershell` (deprecated) 4. `set shell := [...]` Since `set windows-shell` has higher precedence than `set shell`, you can use `set windows-shell` to pick a shell on Windows, and `set shell` to pick a shell for all other platforms. ### Timestamps `just` can print timestamps before each recipe commands: ``` recipe: echo one sleep 2 echo two ``` ``` $ just --timestamp recipe [07:28:46] echo one one [07:28:46] sleep 2 [07:28:48] echo two two ``` By default, timestamps are formatted as `HH:MM:SS`. The format can be changed with `--timestamp-format`: ``` $ just --timestamp recipe --timestamp-format '%H:%M:%S%.3f %Z' [07:32:11:.349 UTC] echo one one [07:32:11:.350 UTC] sleep 2 [07:32:13:.352 UTC] echo two two ``` The argument to `--timestamp-format` is a `strftime`\-style format string, see the [`chrono` library docs](https://docs.rs/chrono/latest/chrono/format/strftime/index.html) for details. ### Signal Handling [Signals](https://en.wikipedia.org/wiki/Signal_\(IPC\)) are messages sent to running programs to trigger specific behavior. For example, `SIGINT` is sent to all processes in the terminal foreground process group when `CTRL-C` is pressed. `just` tries to exit when requested by a signal, but it also tries to avoid leaving behind running child processes, two goals which are somewhat in conflict. If `just` exits leaving behind child processes, the user will have no recourse but to `ps aux | grep` for the children and manually `kill` them, a tedious endeavor. #### Fatal Signals `SIGHUP`, `SIGINT`, and `SIGQUIT` are generated when the user closes the terminal, types `ctrl-c`, or types `ctrl-\`, respectively, and are sent to all processes in the foreground process group. `SIGTERM` is the default signal sent by the `kill` command, and is delivered only to its intended victim. When a child process is not running, `just` will exit immediately on receipt of any of the above signals. When a child process *is* running, `just` will wait until it terminates, to avoid leaving it behind. Additionally, on receipt of `SIGTERM`, `just` will forward `SIGTERM` to any running children1\.41.0, since unlike other fatal signals, `SIGTERM`, was likely sent to `just` alone. Regardless of whether a child process terminates successfully after `just` receives a fatal signal, `just` halts execution. #### `SIGINFO` `SIGINFO` is sent to all processes in the foreground process group when the user types `ctrl-t` on [BSD](https://en.wikipedia.org/wiki/Berkeley_Software_Distribution)\-derived operating systems, including MacOS, but not Linux. `just` responds by printing a list of all child process IDs and commands1\.41.0. #### Windows On Windows, `just` behaves as if it had received `SIGINT` when the user types `ctrl-c`. Other signals are unsupported. ## Changelog A changelog for the latest release is available in [CHANGELOG.md](https://raw.githubusercontent.com/casey/just/master/CHANGELOG.md). Changelogs for previous releases are available on [the releases page](https://github.com/casey/just/releases). `just --changelog` can also be used to make a `just` binary print its changelog. ## Miscellanea ### Re-running recipes when files change [`watchexec`](https://github.com/mattgreen/watchexec) can re-run any command when files change. To re-run the recipe `foo` when any file changes: ``` watchexec just foo ``` See `watchexec --help` for more info, including how to specify which files should be watched for changes. ### Parallelism Dependencies may be run in parallel with the `[parallel]` attribute. In this `justfile`, `foo`, `bar`, and `baz` will execute in parallel when `main` is run: ``` [parallel] main: foo bar baz foo: sleep 1 bar: sleep 1 baz: sleep 1 ``` GNU `parallel` may be used to run recipe lines concurrently: ``` parallel: #!/usr/bin/env -S parallel --shebang --ungroup --jobs {{ num_cpus() }} echo task 1 start; sleep 3; echo task 1 done echo task 2 start; sleep 3; echo task 2 done echo task 3 start; sleep 3; echo task 3 done echo task 4 start; sleep 3; echo task 4 done ``` ### Shell Alias For lightning-fast command running, put `alias j=just` in your shell's configuration file. ### Shell Completion Scripts Shell completion scripts for Bash, Elvish, Fish, Nushell, PowerShell, and Zsh are available in [release archives](https://github.com/casey/just/releases). The `just` binary can also generate the same completion scripts at runtime using `just --completions SHELL`: ``` $ just --completions bash > just ``` #### Bash The recommended approach is to use the `bash-completions` package to lazy-load the completion script: ``` mkdir -p ~/.local/share/bash-completion/completions just --completions bash > ~/.local/share/bash-completion/completions/just ``` If `bash-completions` is not installed, you can source the completion script in your `.bashrc`: ``` source <(just --completions bash) ``` If you use an alias like `alias j=just`, you should also save the completion script with the name `j` when lazy-loading: ``` just --completions bash > ~/.local/share/bash-completion/completions/j ``` Or if not lazy-loading, add this line after sourcing the completion script in your `.bashrc`: ``` complete -F _clap_complete_just -o bashdefault -o default j ``` #### Elvish In your `rc.elv`: ``` set edit:completion:arg-completer[just] = { |@args| eval (just --completions elvish | slurp) set @result = (edit:completion:arg-completer[just] $@args) put $@result } ``` #### Fish Save the completion script to the completions directory to lazy-load it: ``` mkdir -p ~/.config/fish/completions just --completions fish > ~/.config/fish/completions/just.fish ``` #### Nushell First save the completion script: ``` just --completions nushell | save -f ($nu.default-config-dir | path join just.nu) ``` Then in `config.nu`: ``` source just.nu ``` #### PowerShell In your PowerShell `$PROFILE`: ``` just --completions powershell | Out-String | Invoke-Expression ``` #### Zsh First save the completion script: ``` mkdir -p ~/.zsh/completions just --completions zsh > ~/.zsh/completions/_just ``` Then in your `.zshrc`: ``` fpath=(~/.zsh/completions $fpath) autoload -U compinit compinit ``` ### Man Page `just` can print its own man page with `just --man`. Man pages are written in [`roff`](https://en.wikipedia.org/wiki/Roff_%28software%29), a venerable markup language and one of the first practical applications of Unix. If you have [`groff`](https://www.gnu.org/software/groff/) installed you can view the man page with `just --man | groff -mandoc -Tascii | less`. ### Grammar A non-normative grammar of `justfile`s can be found in [GRAMMAR.md](https://github.com/casey/just/blob/master/GRAMMAR.md). ### just.sh Before `just` was a fancy Rust program it was a tiny shell script that called `make`. You can find the old version in [contrib/just.sh](https://github.com/casey/just/blob/master/contrib/just.sh). ### Global and User `justfile`s If you want some recipes to be available everywhere, you have a few options. #### Global Justfile `just --global-justfile`, or `just -g` for short, searches the following paths, in-order, for a justfile: - `$XDG_CONFIG_HOME/just/justfile` - `$HOME/.config/just/justfile` - `$HOME/justfile` - `$HOME/.justfile` You can put recipes that are used across many projects in a global justfile to easily invoke them from any directory. #### User justfile tips You can also adopt some of the following workflows. These tips assume you've created a `justfile` at `~/.user.justfile`, but you can put this `justfile` at any convenient path on your system. ##### Recipe Aliases If you want to call the recipes in `~/.user.justfile` by name, and don't mind creating an alias for every recipe, add the following to your shell's initialization script: ``` for recipe in `just --justfile ~/.user.justfile --summary`; do alias $recipe="just --justfile ~/.user.justfile --working-directory . $recipe" done ``` Now, if you have a recipe called `foo` in `~/.user.justfile`, you can just type `foo` at the command line to run it. It took me way too long to realize that you could create recipe aliases like this. Notwithstanding my tardiness, I am very pleased to bring you this major advance in `justfile` technology. ##### Forwarding Alias If you'd rather not create aliases for every recipe, you can create a single alias: ``` alias .j='just --justfile ~/.user.justfile --working-directory .' ``` Now, if you have a recipe called `foo` in `~/.user.justfile`, you can just type `.j foo` at the command line to run it. I'm pretty sure that nobody actually uses this feature, but it's there. ĀÆ\\\_(惄)\_/ĀÆ ##### Customization You can customize the above aliases with additional options. For example, if you'd prefer to have the recipes in your `justfile` run in your home directory, instead of the current directory: ``` alias .j='just --justfile ~/.user.justfile --working-directory ~' ``` ### Node.js `package.json` Script Compatibility The following export statement gives `just` recipes access to local Node module binaries, and makes `just` recipe commands behave more like `script` entries in Node.js `package.json` files: ``` export PATH := "./node_modules/.bin:" + env_var('PATH') ``` ### Paths on Windows On Windows, all functions that return paths, except `invocation_directory()` will return `\`\-separated paths. When not using PowerShell or `cmd.exe` these paths should be quoted to prevent the `\`s from being interpreted as character escapes: ``` ls: echo '{{absolute_path(".")}}' ``` `cygpath.exe` is an executable included in some distributions of Unix userlands for Windows, including [Cygwin](https://www.cygwin.com/) and [Git](https://git-scm.com/downloads) for Windows. `just` uses `cygpath.exe` in two places: For backwards compatibility, `invocation_directory()`, uses `cygpath.exe` to convert the invocation directory into a unix-style `/`\-separated path. Use `invocation_directory_native()` to get the native, Windows-style path. On unix, `invocation_directory()` and `invocation_directory_native()` both return the same unix-style path. `cygpath.exe` is used also used to convert Unix-style shebang lines into Windows paths. As an alternative, the `[script]` attribute can be used, which does not depend on `cygpath.exe`. If `cygpath.exe` is available, you can use it to convert between path styles: ``` foo_unix := '/hello/world' foo_windows := shell('cygpath --windows $1', foo_unix) bar_windows := 'C:\hello\world' bar_unix := shell('cygpath --unix $1', bar_windows) ``` ### Remote Justfiles If you wish to include a `mod` or `import` source file in many `justfiles` without needing to duplicate it, you can use an optional `mod` or `import`, along with a recipe to fetch the module source: ``` import? 'foo.just' fetch: curl https://raw.githubusercontent.com/casey/just/master/justfile > foo.just ``` Given the above `justfile`, after running `just fetch`, the recipes in `foo.just` will be available. ### Printing Complex Strings `echo` can be used to print strings, but because it processes escape sequences, like `\n`, and different implementations of `echo` recognize different escape sequences, using `printf` is often a better choice. `printf` takes a C-style format string and any number of arguments, which are interpolated into the format string. This can be combined with indented, triple quoted strings to emulate shell heredocs. Substitution complex strings into recipe bodies with `{ā€¦}` can also lead to trouble as it may be split by the shell into multiple arguments depending on the presence of whitespace and quotes. Exporting complex strings as environment variables and referring to them with `"$NAME"`, note the double quotes, can also help. Putting all this together, to print a string verbatim to standard output, with all its various escape sequences and quotes undisturbed: ``` export FOO := ''' a complicated string with some dis\tur\bi\ng escape sequences and "quotes" of 'different' kinds ''' bar: printf %s "$FOO" ``` ### Alternatives and Prior Art There is no shortage of command runners! Some more or less similar alternatives to `just` include: - [make](https://en.wikipedia.org/wiki/Make_\(software\)): The Unix build tool that inspired `just`. There are a few different modern day descendents of the original `make`, including [FreeBSD Make](https://www.freebsd.org/cgi/man.cgi?make\(1\)) and [GNU Make](https://www.gnu.org/software/make/). - [task](https://github.com/go-task/task): A YAML-based command runner written in Go. - [maid](https://github.com/egoist/maid): A Markdown-based command runner written in JavaScript. - [microsoft/just](https://github.com/microsoft/just): A JavaScript-based command runner written in JavaScript. - [cargo-make](https://github.com/sagiegurari/cargo-make): A command runner for Rust projects. - [mmake](https://github.com/tj/mmake): A wrapper around `make` with a number of improvements, including remote includes. - [robo](https://github.com/tj/robo): A YAML-based command runner written in Go. - [mask](https://github.com/jakedeichert/mask): A Markdown-based command runner written in Rust. - [makesure](https://github.com/xonixx/makesure): A simple and portable command runner written in AWK and shell. - [haku](https://github.com/VladimirMarkelov/haku): A make-like command runner written in Rust. - [mise](https://mise.jdx.dev/): A development environment tool manager written in Rust supporting tasks in TOML files and standalone scripts. ## Contributing `just` welcomes your contributions! `just` is released under the maximally permissive [CC0](https://creativecommons.org/publicdomain/zero/1.0/legalcode.txt) public domain dedication and fallback license, so your changes must also be released under this license. ### Getting Started `just` is written in Rust. Use [rustup](https://www.rust-lang.org/tools/install) to install a Rust toolchain. `just` is extensively tested. All new features must be covered by unit or integration tests. Unit tests are under [src](https://github.com/casey/just/blob/master/src), live alongside the code being tested, and test code in isolation. Integration tests are in the [tests directory](https://github.com/casey/just/blob/master/tests) and test the `just` binary from the outside by invoking `just` on a given `justfile` and set of command-line arguments, and checking the output. You should write whichever type of tests are easiest to write for your feature while still providing good test coverage. Unit tests are useful for testing new Rust functions that are used internally and as an aid for development. A good example are the unit tests which cover the [`unindent()` function](https://github.com/casey/just/blob/master/src/unindent.rs), used to unindent triple-quoted strings and backticks. `unindent()` has a bunch of tricky edge cases which are easy to exercise with unit tests that call `unindent()` directly. Integration tests are useful for making sure that the final behavior of the `just` binary is correct. `unindent()` is also covered by integration tests which make sure that evaluating a triple-quoted string produces the correct unindented value. However, there are not integration tests for all possible cases. These are covered by faster, more concise unit tests that call `unindent()` directly. Integration tests use the `Test` struct, a builder which allows for easily invoking `just` with a given `justfile`, arguments, and environment variables, and checking the program's stdout, stderr, and exit code . ### Contribution Workflow 1. Make sure the feature is wanted. There should be an open issue about the feature with a comment from [@casey](https://github.com/casey) saying that it's a good idea or seems reasonable. If there isn't, open a new issue and ask for feedback. There are lots of good features which can't be merged, either because they aren't backwards compatible, have an implementation which would overcomplicate the codebase, or go against `just`'s design philosophy. 2. Settle on the design of the feature. If the feature has multiple possible implementations or syntaxes, make sure to nail down the details in the issue. 3. Clone `just` and start hacking. The best workflow is to have the code you're working on in an editor alongside a job that re-runs tests whenever a file changes. You can run such a job by installing [cargo-watch](https://github.com/watchexec/cargo-watch) with `cargo install cargo-watch` and running `just watch test`. 4. Add a failing test for your feature. Most of the time this will be an integration test which exercises the feature end-to-end. Look for an appropriate file to put the test in [tests](https://github.com/casey/just/blob/master/tests), or add a new file in [tests](https://github.com/casey/just/blob/master/tests) and add a `mod` statement importing that file in [tests/lib.rs](https://github.com/casey/just/blob/master/tests/lib.rs). 5. Implement the feature. 6. Run `just ci` to make sure that all tests, lints, and checks pass. Requires [mdBook](https://github.com/rust-lang/mdBook) and [mdbook-linkcheck](https://github.com/Michael-F-Bryan/mdbook-linkcheck). 7. Open a PR with the new code that is editable by maintainers. PRs often require rebasing and minor tweaks. If the PR is not editable by maintainers, each rebase and tweak will require a round trip of code review. Your PR may be summarily closed if it is not editable by maintainers. 8. Incorporate feedback. 9. Enjoy the sweet feeling of your PR getting merged\! Feel free to open a draft PR at any time for discussion and feedback. ### Hints Here are some hints to get you started with specific kinds of new features, which you can use in addition to the contribution workflow above. #### Adding a New Attribute 1. Write a new integration test in [tests/attributes.rs](https://github.com/casey/just/blob/master/tests/attributes.rs). 2. Add a new variant to the [`Attribute`](https://github.com/casey/just/blob/master/src/attribute.rs) enum. 3. Implement the functionality of the new attribute. 4. Run `just ci` to make sure that all tests pass. ### Janus [Janus](https://github.com/casey/janus) is a tool for checking whether a change to `just` breaks or changes the interpretation of existing `justfile`s. It collects and analyzes public `justfile`s on GitHub. Before merging a particularly large or gruesome change, Janus should be run to make sure that nothing breaks. Don't worry about running Janus yourself, Casey will happily run it for you on changes that need it. ### Minimum Supported Rust Version The minimum supported Rust version, or MSRV, is current stable Rust. It may build on older versions of Rust, but this is not guaranteed. ### New Releases New releases of `just` are made frequently so that users quickly get access to new features. Release commit messages use the following template: ``` Release x.y.z - Bump version: x.y.z ā†’ x.y.z - Update changelog - Update changelog contributor credits - Update dependencies - Update version references in readme ``` ## Frequently Asked Questions ### What are the idiosyncrasies of Make that Just avoids? `make` has some behaviors which are confusing, complicated, or make it unsuitable for use as a general command runner. One example is that under some circumstances, `make` won't actually run the commands in a recipe. For example, if you have a file called `test` and the following makefile: ``` test: ./test ``` `make` will refuse to run your tests: ``` $ make test make: `test' is up to date. ``` `make` assumes that the `test` recipe produces a file called `test`. Since this file exists and the recipe has no other dependencies, `make` thinks that it doesn't have anything to do and exits. To be fair, this behavior is desirable when using `make` as a build system, but not when using it as a command runner. You can disable this behavior for specific targets using `make`'s built-in [`.PHONY` target name](https://www.gnu.org/software/make/manual/html_node/Phony-Targets.html), but the syntax is verbose and can be hard to remember. The explicit list of phony targets, written separately from the recipe definitions, also introduces the risk of accidentally defining a new non-phony target. In `just`, all recipes are treated as if they were phony. Other examples of `make`'s idiosyncrasies include the difference between `=` and `:=` in assignments, the confusing error messages that are produced if you mess up your makefile, needing `$$` to use environment variables in recipes, and incompatibilities between different flavors of `make`. ### What's the relationship between Just and Cargo build scripts? [`cargo` build scripts](http://doc.crates.io/build-script.html) have a pretty specific use, which is to control how `cargo` builds your Rust project. This might include adding flags to `rustc` invocations, building an external dependency, or running some kind of codegen step. `just`, on the other hand, is for all the other miscellaneous commands you might run as part of development. Things like running tests in different configurations, linting your code, pushing build artifacts to a server, removing temporary files, and the like. Also, although `just` is written in Rust, it can be used regardless of the language or build system your project uses. ## Further Ramblings I personally find it very useful to write a `justfile` for almost every project, big or small. On a big project with multiple contributors, it's very useful to have a file with all the commands needed to work on the project close at hand. There are probably different commands to test, build, lint, deploy, and the like, and having them all in one place is useful and cuts down on the time you have to spend telling people which commands to run and how to type them. And, with an easy place to put commands, it's likely that you'll come up with other useful things which are part of the project's collective wisdom, but which aren't written down anywhere, like the arcane commands needed for some part of your revision control workflow, to install all your project's dependencies, or all the random flags you might need to pass to the build system. Some ideas for recipes: - Deploying/publishing the project - Building in release mode vs debug mode - Running in debug mode or with logging enabled - Complex git workflows - Updating dependencies - Running different sets of tests, for example fast tests vs slow tests, or running them with verbose output - Any complex set of commands that you really should write down somewhere, if only to be able to remember them Even for small, personal projects it's nice to be able to remember commands by name instead of ^Reverse searching your shell history, and it's a huge boon to be able to go into an old project written in a random language with a mysterious build system and know that all the commands you need to do whatever you need to do are in the `justfile`, and that if you type `just` something useful (or at least interesting!) will probably happen. For ideas for recipes, check out [this project's `justfile`](https://github.com/casey/just/blob/master/justfile), or some of the `justfile`s [out in the wild](https://github.com/search?q=path%3A**%2Fjustfile&type=code). Anyways, I think that's about it for this incredibly long-winded README. I hope you enjoy using `just` and find great success and satisfaction in all your computational endeavors\! šŸ˜ø [šŸ”¼ Back to the top\!](https://github.com/casey/just#just) ## About šŸ¤– Just a command runner [just.systems](https://just.systems/ "https://just.systems") ### Resources [Readme](https://github.com/casey/just#readme-ov-file) ### License [CC0-1.0 license](https://github.com/casey/just#CC0-1.0-1-ov-file) ### Contributing [Contributing](https://github.com/casey/just#contributing-ov-file) ### Uh oh\! There was an error while loading. [Please reload this page](https://github.com/casey/just). [Activity](https://github.com/casey/just/activity) ### Stars [**32\.5k** stars](https://github.com/casey/just/stargazers) ### Watchers [**87** watching](https://github.com/casey/just/watchers) ### Forks [**710** forks](https://github.com/casey/just/forks) [Report repository](https://github.com/contact/report-content?content_url=https%3A%2F%2Fgithub.com%2Fcasey%2Fjust&report=casey+%28user%29) ## [Releases 135](https://github.com/casey/just/releases) [1\.48.1 Latest Mar 28, 2026](https://github.com/casey/just/releases/tag/1.48.1) [\+ 134 releases](https://github.com/casey/just/releases) ## [Packages 1](https://github.com/users/casey/packages?repo_name=just) - [just](https://github.com/users/casey/packages/container/package/just) ## [Used by 257](https://github.com/casey/just/network/dependents) [![@rdawebb](https://avatars.githubusercontent.com/u/41092222?s=64&v=4) ![@FiazTechnologies](https://avatars.githubusercontent.com/u/141745376?s=64&v=4) ![@lina-roether](https://avatars.githubusercontent.com/u/35772525?s=64&v=4) ![@muhammad-fiaz](https://avatars.githubusercontent.com/u/75434191?s=64&v=4) ![@oilcrest](https://avatars.githubusercontent.com/u/43282831?s=64&v=4) ![@devnexen](https://avatars.githubusercontent.com/u/4922778?s=64&v=4) ![@intrigus-lgtm](https://avatars.githubusercontent.com/u/60750685?s=64&v=4) ![@clayne](https://avatars.githubusercontent.com/u/2467434?s=64&v=4) + 249](https://github.com/casey/just/network/dependents) ## [Contributors](https://github.com/casey/just/graphs/contributors) ### Uh oh\! 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Table of Contents ā†—ļø [![crates.io version](https://camo.githubusercontent.com/acf15ac5756065b9f9d8590fd6f42709d004452ac2b4816823dc40528a74ffc5/68747470733a2f2f696d672e736869656c64732e696f2f6372617465732f762f6a7573742e737667)](https://crates.io/crates/just) [![build status](https://github.com/casey/just/actions/workflows/ci.yaml/badge.svg)](https://github.com/casey/just/actions/workflows/ci.yaml) [![downloads](https://camo.githubusercontent.com/3e2c0d79862f904f825c929a13c680efa566026e3f9965f5e0ad01fe2f9a503e/68747470733a2f2f696d672e736869656c64732e696f2f6769746875622f646f776e6c6f6164732f63617365792f6a7573742f746f74616c2e737667)](https://github.com/casey/just/releases) [![chat on discord](https://camo.githubusercontent.com/aa85ec82bf82099dca55b33244b99a0c7e22544ce66584ae3416aa9e2350bb3f/68747470733a2f2f696d672e736869656c64732e696f2f646973636f72642f3639353538303036393833373430363232383f6c6f676f3d646973636f7264)](https://discord.gg/ezYScXR) [![say thanks](https://camo.githubusercontent.com/ee843c523d57170345478ba1c560741cf66c2e266144266ccd1ab0c51b7f87a5/68747470733a2f2f696d672e736869656c64732e696f2f62616467652f5361792532305468616e6b732d212d3145414544422e737667)](mailto:casey@rodarmor.com?subject=Thanks%20for%20Just!) `just` is a handy way to save and run project-specific commands. This readme is also available as a [book](https://just.systems/man/en/). The book reflects the latest release, whereas the [readme on GitHub](https://github.com/casey/just/blob/master/README.md) reflects latest master. (äø­ę–‡ę–‡ę”£åœØ [čæ™é‡Œ](https://github.com/casey/just/blob/master/README.%E4%B8%AD%E6%96%87.md), åæ«ēœ‹čæ‡ę„!) Commands, called recipes, are stored in a file called `justfile` with syntax inspired by `make`: [![screenshot](https://raw.githubusercontent.com/casey/just/master/etc/screenshot.png)](https://raw.githubusercontent.com/casey/just/master/etc/screenshot.png) You can then run them with `just RECIPE`: ``` $ just test-all cc *.c -o main ./test --all Yay, all your tests passed! ``` `just` has a ton of useful features, and many improvements over `make`: - `just` is a command runner, not a build system, so it avoids much of [`make`'s complexity and idiosyncrasies](https://github.com/casey/just#what-are-the-idiosyncrasies-of-make-that-just-avoids). No need for `.PHONY` recipes\! - Linux, MacOS, Windows, and other reasonable unices are supported with no additional dependencies. (Although if your system doesn't have an `sh`, you'll need to [choose a different shell](https://github.com/casey/just#shell).) - Errors are specific and informative, and syntax errors are reported along with their source context. - Recipes can accept [command line arguments](https://github.com/casey/just#recipe-parameters). - Wherever possible, errors are resolved statically. Unknown recipes and circular dependencies are reported before anything runs. - `just` [loads `.env` files](https://github.com/casey/just#dotenv-settings), making it easy to populate environment variables. - Recipes can be [listed from the command line](https://github.com/casey/just#listing-available-recipes). - Command line completion scripts are [available for most popular shells](https://github.com/casey/just#shell-completion-scripts). - Recipes can be written in [arbitrary languages](https://github.com/casey/just#shebang-recipes), like Python or NodeJS. - `just` can be invoked from any subdirectory, not just the directory that contains the `justfile`. - And [much more](https://just.systems/man/en/)\! If you need help with `just` please feel free to open an issue or ping me on [Discord](https://discord.gg/ezYScXR). Feature requests and bug reports are always welcome\! Installation Prerequisites `just` should run on any system with a reasonable `sh`, including Linux, MacOS, and the BSDs. Windows On Windows, `just` works with the `sh` provided by [Git for Windows](https://git-scm.com/), [GitHub Desktop](https://desktop.github.com/), or [Cygwin](http://www.cygwin.com/). After installation, `sh` must be available in the `PATH` of the shell you want to invoke `just` from. If you'd rather not install `sh`, you can use the `shell` setting to use the shell of your choice. Like PowerShell: ``` # use PowerShell instead of sh: set shell := ["powershell.exe", "-c"] hello: Write-Host "Hello, world!" ``` ā€¦or `cmd.exe`: ``` # use cmd.exe instead of sh: set shell := ["cmd.exe", "/c"] list: dir ``` You can also set the shell using command-line arguments. For example, to use PowerShell, launch `just` with `--shell powershell.exe --shell-arg -c`. (PowerShell is installed by default on Windows 7 SP1 and Windows Server 2008 R2 S1 and later, and `cmd.exe` is quite fiddly, so PowerShell is recommended for most Windows users.) Packages Cross-platform | Package Manager | Package | Command | |---|---|---| | [arkade](https://github.com/alexellis/arkade) | just | `arkade get just` | | [asdf](https://asdf-vm.com/) | [just](https://github.com/olofvndrhr/asdf-just) | `asdf plugin add just` `asdf install just <version>` | | [Cargo](https://www.rust-lang.org/) | [just](https://crates.io/crates/just) | `cargo install just` | | [Cargo Binstall](https://github.com/cargo-bins/cargo-binstall) | [just](https://crates.io/crates/just) | `cargo binstall just` | | [Conda](https://docs.conda.io/projects/conda/en/latest/index.html) | [just](https://anaconda.org/conda-forge/just) | `conda install -c conda-forge just` | | [Homebrew](https://brew.sh/) | [just](https://formulae.brew.sh/formula/just) | `brew install just` | | [Nix](https://nixos.org/nix/) | [just](https://github.com/NixOS/nixpkgs/blob/master/pkgs/by-name/ju/just/package.nix) | `nix-env -iA nixpkgs.just` | | [npm](https://www.npmjs.com/) | [rust-just](https://www.npmjs.com/package/rust-just) | `npm install -g rust-just` | | [pipx](https://pipx.pypa.io/stable/) | [rust-just](https://pypi.org/project/rust-just/) | `pipx install rust-just` | | [Snap](https://snapcraft.io/) | [just](https://snapcraft.io/just) | `snap install --edge --classic just` | | [uv](https://docs.astral.sh/uv/) | [rust-just](https://pypi.org/project/rust-just/) | `uv tool install rust-just` | BSD | Operating System | Package Manager | Package | Command | |---|---|---|---| | [FreeBSD](https://www.freebsd.org/) | [pkg](https://www.freebsd.org/doc/handbook/pkgng-intro.html) | [just](https://www.freshports.org/deskutils/just/) | `pkg install just` | | [OpenBSD](https://www.openbsd.org/) | [pkg\_\*](https://www.openbsd.org/faq/faq15.html) | [just](https://cvsweb.openbsd.org/cgi-bin/cvsweb/ports/sysutils/just) | `pkg_add just` | Linux | Operating System | Package Manager | Package | Command | |---|---|---|---| | [Alpine](https://alpinelinux.org/) | [apk-tools](https://wiki.alpinelinux.org/wiki/Alpine_Linux_package_management) | [just](https://pkgs.alpinelinux.org/package/edge/community/x86_64/just) | `apk add just` | | [Arch](https://www.archlinux.org/) | [pacman](https://wiki.archlinux.org/title/Pacman) | [just](https://archlinux.org/packages/extra/x86_64/just/) | `pacman -S just` | | [Debian 13](https://debian.org/) and [Ubuntu 24.04](https://ubuntu.com/) derivatives | [apt](https://en.wikipedia.org/wiki/APT_\(software\)) | [just](https://packages.debian.org/trixie/just) | `apt install just` | | [Fedora](https://getfedora.org/) | [DNF](https://dnf.readthedocs.io/en/latest/) | [just](https://src.fedoraproject.org/rpms/rust-just) | `dnf install just` | | [Gentoo](https://www.gentoo.org/) | [Portage](https://wiki.gentoo.org/wiki/Portage) | [dev-build/just](https://packages.gentoo.org/packages/dev-build/just) | `emerge -av dev-build/just` | | [NixOS](https://nixos.org/nixos/) | [Nix](https://nixos.org/nix/) | [just](https://github.com/NixOS/nixpkgs/blob/master/pkgs/by-name/ju/just/package.nix) | `nix-env -iA nixos.just` | | [openSUSE](https://opensuse.org/) | [Zypper](https://en.opensuse.org/Portal:Zypper) | [just](https://build.opensuse.org/package/show/Base:System/just) | `zypper in just` | | [Solus](https://getsol.us/) | [eopkg](https://getsol.us/articles/package-management/basics/en) | [just](https://dev.getsol.us/source/just/) | `eopkg install just` | | [Void](https://voidlinux.org/) | [XBPS](https://wiki.voidlinux.org/XBPS) | [just](https://github.com/void-linux/void-packages/blob/master/srcpkgs/just/template) | `xbps-install -S just` | Windows | Package Manager | Package | Command | |---|---|---| | [Chocolatey](https://chocolatey.org/) | [just](https://github.com/michidk/just-choco) | `choco install just` | | [Scoop](https://scoop.sh/) | [just](https://github.com/ScoopInstaller/Main/blob/master/bucket/just.json) | `scoop install just` | | [Windows Package Manager](https://learn.microsoft.com/en-us/windows/package-manager/) | [Casey/Just](https://github.com/microsoft/winget-pkgs/tree/master/manifests/c/Casey/Just) | `winget install --id Casey.Just --exact` | macOS | Package Manager | Package | Command | |---|---|---| | [MacPorts](https://www.macports.org/) | [just](https://ports.macports.org/port/just/summary) | `port install just` | [![just package version table](https://camo.githubusercontent.com/0ebfbd07d3da9aaadf8971e68490391c726ac2c60f86a3b4400e5b55421acda8/68747470733a2f2f7265706f6c6f67792e6f72672f62616467652f766572746963616c2d616c6c7265706f732f6a7573742e737667)](https://camo.githubusercontent.com/0ebfbd07d3da9aaadf8971e68490391c726ac2c60f86a3b4400e5b55421acda8/68747470733a2f2f7265706f6c6f67792e6f72672f62616467652f766572746963616c2d616c6c7265706f732f6a7573742e737667) Pre-Built Binaries Pre-built binaries for Linux, MacOS, and Windows can be found on [the releases page](https://github.com/casey/just/releases). You can use the following command on Linux, MacOS, or Windows to download the latest release, just replace `DEST` with the directory where you'd like to put `just`: ``` curl --proto '=https' --tlsv1.2 -sSf https://just.systems/install.sh | bash -s -- --to DEST ``` For example, to install `just` to `~/bin`: ``` # create ~/bin mkdir -p ~/bin # download and extract just to ~/bin/just curl --proto '=https' --tlsv1.2 -sSf https://just.systems/install.sh | bash -s -- --to ~/bin # add `~/bin` to the paths that your shell searches for executables # this line should be added to your shells initialization file, # e.g. `~/.bashrc` or `~/.zshrc` export PATH="$PATH:$HOME/bin" # just should now be executable just --help ``` Note that `install.sh` may fail on GitHub Actions, or in other environments where many machines share IP addresses. `install.sh` calls GitHub APIs in order to determine the latest version of `just` to install, and those API calls are rate-limited on a per-IP basis. To make `install.sh` more reliable in such circumstances, pass a specific tag to install with `--tag`. Another way to avoid rate-limiting is to pass a GitHub authentication token to `install.sh` as an environment variable named `GITHUB_TOKEN`, allowing it to authenticate its requests. [Releases](https://github.com/casey/just/releases) include a `SHA256SUM` file which can be used to verify the integrity of pre-built binary archives. To verify a release, download the pre-built binary archive along with the `SHA256SUM` file and run: ``` shasum --algorithm 256 --ignore-missing --check SHA256SUMS ``` GitHub Actions `just` can be installed on GitHub Actions in a few ways. Using package managers pre-installed on GitHub Actions runners on MacOS with `brew install just`, and on Windows with `choco install just`. With [extractions/setup-just](https://github.com/extractions/setup-just): ``` - uses: extractions/setup-just@v3 with: just-version: 1.5.0 # optional semver specification, otherwise latest ``` Or with [taiki-e/install-action](https://github.com/taiki-e/install-action): ``` - uses: taiki-e/install-action@just ``` Docker `just` is available as a Docker image from [the GitHub Container Registry](https://ghcr.io/casey/just). To copy `just` into a Docker image, add the following line to your `Dockerfile`: ``` COPY --from=ghcr.io/casey/just:latest /just /usr/local/bin/ ``` After copying, `just` may also be used as part of a docker build: ``` RUN just ``` Release RSS Feed An [RSS feed](https://en.wikipedia.org/wiki/RSS) of `just` releases is available [here](https://github.com/casey/just/releases.atom). Node.js Installation [just-install](https://npmjs.com/package/just-install) can be used to automate installation of `just` in Node.js applications. `just` is a great, more robust alternative to npm scripts. If you want to include `just` in the dependencies of a Node.js application, `just-install` will install a local, platform-specific binary as part of the `npm install` command. This removes the need for every developer to install `just` independently using one of the processes mentioned above. After installation, the `just` command will work in npm scripts or with npx. It's great for teams who want to make the set up process for their project as easy as possible. For more information, see the [just-install README file](https://github.com/brombal/just-install#readme). Nix Flake The `just` repository includes a [`flake.nix`](https://github.com/casey/just/tree/master/flake.nix) that defines a [nix flake](https://nix.dev/concepts/flakes.html), allowing you to use `just` as an input to another flake: ``` { inputs = { just.url = "github:casey/just"; } outputs = {self, nixpkgs, just}: { } } ``` Backwards Compatibility With the release of version 1.0, `just` features a strong commitment to backwards compatibility and stability. Future releases will not introduce backwards incompatible changes that make existing `justfile`s stop working, or break working invocations of the command-line interface. This does not, however, preclude fixing outright bugs, even if doing so might break `justfiles` that rely on their behavior. There will never be a `just` 2.0. Any desirable backwards-incompatible changes will be opt-in on a per-`justfile` basis, so users may migrate at their leisure. Features that aren't yet ready for stabilization are marked as unstable and may be changed or removed at any time. Using unstable features produces an error by default, which can be suppressed by passing the `--unstable` flag, `set unstable`, or setting the environment variable `JUST_UNSTABLE`, to any value other than `false`, `0`, or the empty string. Editor Support `justfile` syntax is close enough to `make` that you may want to tell your editor to use `make` syntax highlighting for `just`. Vim and Neovim Vim version 9.1.1042 or better and Neovim version 0.11 or better support Justfile syntax highlighting out of the box, thanks to [pbnj](https://github.com/pbnj). `vim-just` The [vim-just](https://github.com/NoahTheDuke/vim-just) plugin provides syntax highlighting for `justfile`s. Install it with your favorite package manager, like [Plug](https://github.com/junegunn/vim-plug): ``` call plug#begin() Plug 'NoahTheDuke/vim-just' call plug#end() ``` Or with Vim's built-in package support: ``` mkdir -p ~/.vim/pack/vendor/start cd ~/.vim/pack/vendor/start git clone https://github.com/NoahTheDuke/vim-just.git ``` `tree-sitter-just` [tree-sitter-just](https://github.com/IndianBoy42/tree-sitter-just) is an [Nvim Treesitter](https://github.com/nvim-treesitter/nvim-treesitter) plugin for Neovim. Emacs [just-mode](https://github.com/leon-barrett/just-mode.el) provides syntax highlighting and automatic indentation of `justfile`s. It is available on [MELPA](https://melpa.org/) as [just-mode](https://melpa.org/#/just-mode). [justl](https://github.com/psibi/justl.el) provides commands for executing and listing recipes. You can add the following to an individual `justfile` to enable `make` mode on a per-file basis: ``` # Local Variables: # mode: makefile # End: ``` Visual Studio Code An extension for VS Code is [available here](https://github.com/nefrob/vscode-just). Unmaintained VS Code extensions include [skellock/vscode-just](https://github.com/skellock/vscode-just) and [sclu1034/vscode-just](https://github.com/sclu1034/vscode-just). JetBrains IDEs A plugin for JetBrains IDEs by [linux\_china](https://github.com/linux-china) is [available here](https://plugins.jetbrains.com/plugin/18658-just). Kakoune Kakoune supports `justfile` syntax highlighting out of the box, thanks to TeddyDD. Helix [Helix](https://helix-editor.com/) supports `justfile` syntax highlighting out-of-the-box since version 23.05. Sublime Text The [Just package](https://github.com/nk9/just_sublime) by [nk9](https://github.com/nk9) with `just` syntax and some other tools is available on [PackageControl](https://packagecontrol.io/packages/Just). Micro [Micro](https://micro-editor.github.io/) supports Justfile syntax highlighting out of the box, thanks to [tomodachi94](https://github.com/tomodachi94). Zed The [zed-just](https://github.com/jackTabsCode/zed-just/) extension by [jackTabsCode](https://github.com/jackTabsCode) is available on the [Zed extensions page](https://zed.dev/extensions?query=just). Other Editors Feel free to send me the commands necessary to get syntax highlighting working in your editor of choice so that I may include them here. Language Server Protocol [just-lsp](https://github.com/terror/just-lsp) provides a [language server protocol](https://en.wikipedia.org/wiki/Language_Server_Protocol) implementation, enabling features such as go-to-definition, inline diagnostics, and code completion. Model Context Protocol [just-mcp](http://github.com/promptexecution/just-mcp) provides a [model context protocol](https://en.wikipedia.org/wiki/Model_Context_Protocol) adapter to allow LLMs to query the contents of `justfiles` and run recipes. Quick Start See the installation section for how to install `just` on your computer. Try running `just --version` to make sure that it's installed correctly. For an overview of the syntax, check out [this cheatsheet](https://cheatography.com/linux-china/cheat-sheets/justfile/). Once `just` is installed and working, create a file named `justfile` in the root of your project with the following contents: ``` recipe-name: echo 'This is a recipe!' # this is a comment another-recipe: @echo 'This is another recipe.' ``` When you invoke `just` it looks for file `justfile` in the current directory and upwards, so you can invoke it from any subdirectory of your project. The search for a `justfile` is case insensitive, so any case, like `Justfile`, `JUSTFILE`, or `JuStFiLe`, will work. `just` will also look for files with the name `.justfile`, in case you'd like to hide a `justfile`. Running `just` with no arguments runs the first recipe in the `justfile`: ``` $ just echo 'This is a recipe!' This is a recipe! ``` One or more arguments specify the recipe(s) to run: ``` $ just another-recipe This is another recipe. ``` `just` prints each command to standard error before running it, which is why `echo 'This is a recipe!'` was printed. This is suppressed for lines starting with `@`, which is why `echo 'This is another recipe.'` was not printed. Recipes stop running if a command fails. Here `cargo publish` will only run if `cargo test` succeeds: ``` publish: cargo test # tests passed, time to publish! cargo publish ``` Recipes can depend on other recipes. Here the `test` recipe depends on the `build` recipe, so `build` will run before `test`: ``` build: cc main.c foo.c bar.c -o main test: build ./test sloc: @echo "`wc -l *.c` lines of code" ``` ``` $ just test cc main.c foo.c bar.c -o main ./test testingā€¦ all tests passed! ``` Recipes without dependencies will run in the order they're given on the command line: ``` $ just build sloc cc main.c foo.c bar.c -o main 1337 lines of code ``` Dependencies will always run first, even if they are passed after a recipe that depends on them: ``` $ just test build cc main.c foo.c bar.c -o main ./test testingā€¦ all tests passed! ``` Recipes may depend on recipes in submodules: ``` mod foo baz: foo::bar ``` Examples A variety of `justfile`s can be found in the [examples directory](https://github.com/casey/just/tree/master/examples) and on [GitHub](https://github.com/search?q=path%3A**%2Fjustfile&type=code). Features The Default Recipe When `just` is invoked without a recipe, it runs the recipe with the `[default]` attribute, or the first recipe in the `justfile` if no recipe has the `[default]` attribute. This recipe might be the most frequently run command in the project, like running the tests: ``` test: cargo test ``` You can also use dependencies to run multiple recipes by default: ``` default: lint build test build: echo Buildingā€¦ test: echo Testingā€¦ lint: echo Lintingā€¦ ``` If no recipe makes sense as the default recipe, you can add a recipe to the beginning of your `justfile` that lists the available recipes: ``` default: just --list ``` Listing Available Recipes Recipes can be listed in alphabetical order with `just --list`: ``` $ just --list Available recipes: build test deploy lint ``` Recipes in [submodules](https://github.com/casey/just#modules) can be listed with `just --list PATH`, where `PATH` is a space- or `::`\-separated module path: ``` $ cat justfile mod foo $ cat foo.just mod bar $ cat bar.just baz: $ just --list foo bar Available recipes: baz $ just --list foo::bar Available recipes: baz ``` `just --summary` is more concise: ``` $ just --summary build test deploy lint ``` Pass `--unsorted` to print recipes in the order they appear in the `justfile`: ``` test: echo 'Testing!' build: echo 'Building!' ``` ``` $ just --list --unsorted Available recipes: test build ``` ``` $ just --summary --unsorted test build ``` If you'd like `just` to default to listing the recipes in the `justfile`, you can use this as your default recipe: ``` default: @just --list ``` Note that you may need to add `--justfile {{justfile()}}` to the line above. Without it, if you executed `just -f /some/distant/justfile -d .` or `just -f ./non-standard-justfile`, the plain `just --list` inside the recipe would not necessarily use the file you provided. It would try to find a justfile in your current path, maybe even resulting in a `No justfile found` error. The heading text can be customized with `--list-heading`: ``` $ just --list --list-heading $'Cool stuffā€¦\n' Cool stuffā€¦ test build ``` And the indentation can be customized with `--list-prefix`: ``` $ just --list --list-prefix Ā·Ā·Ā·Ā· Available recipes: Ā·Ā·Ā·Ā·test Ā·Ā·Ā·Ā·build ``` The argument to `--list-heading` replaces both the heading and the newline following it, so it should contain a newline if non-empty. It works this way so you can suppress the heading line entirely by passing the empty string: ``` $ just --list --list-heading '' test build ``` Invoking Multiple Recipes Multiple recipes may be invoked on the command line at once: ``` build: make web serve: python3 -m http.server -d out 8000 ``` ``` $ just build serve make web python3 -m http.server -d out 8000 ``` Keep in mind that recipes with parameters will swallow arguments, even if they match the names of other recipes: ``` build project: make {{project}} serve: python3 -m http.server -d out 8000 ``` ``` $ just build serve make: *** No rule to make target `serve'. Stop. ``` The `--one` flag can be used to restrict command-line invocations to a single recipe: ``` $ just --one build serve error: Expected 1 command-line recipe invocation but found 2. ``` Working Directory By default, recipes run with the working directory set to the directory that contains the `justfile`. The `[no-cd]` attribute can be used to make recipes run with the working directory set to directory in which `just` was invoked. ``` @foo: pwd [no-cd] @bar: pwd ``` ``` $ cd subdir $ just foo / $ just bar /subdir ``` You can override the working directory for all recipes with `set working-directory := 'ā€¦'`: ``` set working-directory := 'bar' @foo: pwd ``` ``` $ pwd /home/bob $ just foo /home/bob/bar ``` You can override the working directory for a specific recipe with the `working-directory` attribute1\.38.0: ``` [working-directory: 'bar'] @foo: pwd ``` ``` $ pwd /home/bob $ just foo /home/bob/bar ``` The argument to the `working-directory` setting or `working-directory` attribute may be absolute or relative. If it is relative it is interpreted relative to the default working directory. Aliases Aliases allow recipes to be invoked on the command line with alternative names: ``` alias b := build build: echo 'Building!' ``` ``` $ just b echo 'Building!' Building! ``` The target of an alias may be a recipe in a submodule: ``` mod foo alias baz := foo::bar ``` Settings Settings control interpretation and execution. Each setting may be specified at most once, anywhere in the `justfile`. For example: ``` set shell := ["zsh", "-cu"] foo: # this line will be run as `zsh -cu 'ls **/*.txt'` ls **/*.txt ``` Table of Settings | Name | Value | Default | Description | |---|---|---|---| | `allow-duplicate-recipes` | boolean | `false` | Allow recipes appearing later in a `justfile` to override earlier recipes with the same name. | | `allow-duplicate-variables` | boolean | `false` | Allow variables appearing later in a `justfile` to override earlier variables with the same name. | | `dotenv-filename` | string | \- | Load a `.env` file with a custom name, if present. | | `dotenv-load` | boolean | `false` | Load a `.env` file, if present. | | `dotenv-override` | boolean | `false` | Override existing environment variables with values from the `.env` file. | | `dotenv-path` | string | \- | Load a `.env` file from a custom path and error if not present. Overrides `dotenv-filename`. | | `dotenv-required` | boolean | `false` | Error if a `.env` file isn't found. | | `export` | boolean | `false` | Export all variables as environment variables. | | `fallback` | boolean | `false` | Search `justfile` in parent directory if the first recipe on the command line is not found. | | `ignore-comments` | boolean | `false` | Ignore recipe lines beginning with `#`. | | `lazy`1\.47.0 | boolean | `false` | Don't evaluate unused variables. | | `positional-arguments` | boolean | `false` | Pass positional arguments. | | `quiet` | boolean | `false` | Disable echoing recipe lines before executing. | | `script-interpreter`1\.33.0 | `[COMMAND, ARGSā€¦]` | `['sh', '-eu']` | Set command used to invoke recipes with empty `[script]` attribute. | | `shell` | `[COMMAND, ARGSā€¦]` | \- | Set command used to invoke recipes and evaluate backticks. | | `tempdir` | string | \- | Create temporary directories in `tempdir` instead of the system default temporary directory. | | `unstable`1\.31.0 | boolean | `false` | Enable unstable features. | | `windows-powershell` | boolean | `false` | Use PowerShell on Windows as default shell. (Deprecated. Use `windows-shell` instead. | | `windows-shell` | `[COMMAND, ARGSā€¦]` | \- | Set the command used to invoke recipes and evaluate backticks. | | `working-directory`1\.33.0 | string | \- | Set the working directory for recipes and backticks, relative to the default working directory. | Boolean settings can be written as: ``` set NAME ``` Which is equivalent to: ``` set NAME := true ``` Non-boolean settings can be set to both strings and expressions.1\.46.0 However, because settings affect the behavior of backticks and many functions, those expressions may not contain backticks or function calls, directly or transitively via reference. Allow Duplicate Recipes If `allow-duplicate-recipes` is set to `true`, defining multiple recipes with the same name is not an error and the last definition is used. Defaults to `false`. ``` set allow-duplicate-recipes @foo: echo foo @foo: echo bar ``` ``` $ just foo bar ``` Allow Duplicate Variables If `allow-duplicate-variables` is set to `true`, defining multiple variables with the same name is not an error and the last definition is used. Defaults to `false`. ``` set allow-duplicate-variables a := "foo" a := "bar" @foo: echo {{a}} ``` ``` $ just foo bar ``` Dotenv Settings If any of `dotenv-load`, `dotenv-filename`, `dotenv-override`, `dotenv-path`, or `dotenv-required` are set, `just` will try to load environment variables from a file. If `dotenv-path` is set, `just` will look for a file at the given path, which may be absolute, or relative to the working directory. The command-line option `--dotenv-path`, short form `-E`, can be used to set or override `dotenv-path` at runtime. If `dotenv-filename` is set `just` will look for a file at the given path, relative to the working directory and each of its ancestors. If `dotenv-filename` is not set, but `dotenv-load` or `dotenv-required` are set, just will look for a file named `.env`, relative to the working directory and each of its ancestors. `dotenv-filename` and `dotenv-path` are similar, but `dotenv-path` is only checked relative to the working directory, whereas `dotenv-filename` is checked relative to the working directory and each of its ancestors. It is not an error if an environment file is not found, unless `dotenv-required` is set. The loaded variables are environment variables, not `just` variables, and so must be accessed using `$VARIABLE_NAME` in recipes and backticks. If `dotenv-override` is set, variables from the environment file will override existing environment variables. For example, if your `.env` file contains: ``` # a comment, will be ignored DATABASE_ADDRESS=localhost:6379 SERVER_PORT=1337 ``` And your `justfile` contains: ``` set dotenv-load serve: @echo "Starting server with database $DATABASE_ADDRESS on port $SERVER_PORTā€¦" ./server --database $DATABASE_ADDRESS --port $SERVER_PORT ``` `just serve` will output: ``` $ just serve Starting server with database localhost:6379 on port 1337ā€¦ ./server --database $DATABASE_ADDRESS --port $SERVER_PORT ``` Export The `export` setting causes all `just` variables to be exported as environment variables. Defaults to `false`. ``` set export a := "hello" @foo b: echo $a echo $b ``` ``` $ just foo goodbye hello goodbye ``` Lazy The `lazy` setting1\.47.0 causes the evaluator to skip evaluating unused variables. This can be beneficial when a `justfile` contains variables that are expensive to evaluate but only sometimes used. In the following `justfile`, `token` will be skipped when only invoking `bar`: ``` set lazy token := `expensive-script-to-get-credentials` foo: curl -H "Authorization: Bearer {{ token }}" https://example.com/foo bar: cargo test ``` Because `just` cannot determine when exported variables are used, assignments with `export` and assignments in a module with `set export` will always be evaluated. Positional Arguments If `positional-arguments` is `true`, recipe arguments will be passed as positional arguments to commands. For linewise recipes, argument `$0` will be the name of the recipe. For example, running this recipe: ``` set positional-arguments @foo bar: echo $0 echo $1 ``` Will produce the following output: ``` $ just foo hello foo hello ``` When using an `sh`\-compatible shell, such as `bash` or `zsh`, `$@` expands to the positional arguments given to the recipe, starting from one. When used within double quotes as `"$@"`, arguments including whitespace will be passed on as if they were double-quoted. That is, `"$@"` is equivalent to `"$1" "$2"`ā€¦ When there are no positional parameters, `"$@"` and `$@` expand to nothing (i.e., they are removed). This example recipe will print arguments one by one on separate lines: ``` set positional-arguments @test *args='': bash -c 'while (( "$#" )); do echo - $1; shift; done' -- "$@" ``` Running it with *two* arguments: ``` $ just test foo "bar baz" - foo - bar baz ``` Positional arguments may also be turned on a per-recipe basis with the `[positional-arguments]` attribute1\.29.0: ``` [positional-arguments] @foo bar: echo $0 echo $1 ``` Note that PowerShell does not handle positional arguments in the same way as other shells, so turning on positional arguments will likely break recipes that use PowerShell. If using PowerShell 7.4 or better, the `-CommandWithArgs` flag will make positional arguments work as expected: ``` set shell := ['pwsh.exe', '-CommandWithArgs'] set positional-arguments print-args a b c: Write-Output @($args[1..($args.Count - 1)]) ``` Shell The `shell` setting controls the command used to invoke recipe lines and backticks. Shebang recipes are unaffected. The default shell is `sh -cu`. ``` # use python3 to execute recipe lines and backticks set shell := ["python3", "-c"] # use print to capture result of evaluation foos := `print("foo" * 4)` foo: print("Snake snake snake snake.") print("{{foos}}") ``` `just` passes the command to be executed as an argument. Many shells will need an additional flag, often `-c`, to make them evaluate the first argument. Windows Shell `just` uses `sh` on Windows by default. To use a different shell on Windows, use `windows-shell`: ``` set windows-shell := ["powershell.exe", "-NoLogo", "-Command"] hello: Write-Host "Hello, world!" ``` See [powershell.just](https://github.com/casey/just/blob/master/examples/powershell.just) for a justfile that uses PowerShell on all platforms. Windows PowerShell *`set windows-powershell` uses the legacy `powershell.exe` binary, and is no longer recommended. See the `windows-shell` setting above for a more flexible way to control which shell is used on Windows.* `just` uses `sh` on Windows by default. To use `powershell.exe` instead, set `windows-powershell` to true. ``` set windows-powershell := true hello: Write-Host "Hello, world!" ``` Python 3 ``` set shell := ["python3", "-c"] ``` Bash ``` set shell := ["bash", "-uc"] ``` Z Shell ``` set shell := ["zsh", "-uc"] ``` Fish ``` set shell := ["fish", "-c"] ``` Nushell ``` set shell := ["nu", "-c"] ``` If you want to change the default table mode to `light`: ``` set shell := ['nu', '-m', 'light', '-c'] ``` *[Nushell](https://github.com/nushell/nushell) was written in Rust, and **has cross-platform support for Windows / macOS and Linux**.* Documentation Comments Comments immediately preceding a recipe will appear in `just --list`: ``` # build stuff build: ./bin/build # test stuff test: ./bin/test ``` ``` $ just --list Available recipes: build # build stuff test # test stuff ``` The `[doc]` attribute can be used to set or suppress a recipe's doc comment: ``` # This comment won't appear [doc('Build stuff')] build: ./bin/build # This one won't either [doc] test: ./bin/test ``` ``` $ just --list Available recipes: build # Build stuff test ``` Variables and Assignments Module-level variables may be created by assigning them a value with `:=`: ``` foo := "hello" bar := "world" baz: echo {{ foo + " " + bar }} ``` All variables in a module may be printed: ``` $ just --evaluate bar := "world" foo := "hello" ``` Or the value of a single variable: ``` $ just --evalaute foo hello ``` All variables in a submodule or a single variable in a submodule may be printed with a path to the submodule or variablemaster: ``` $ just --evaluate bob::bar x := "world" y := "hello" $ just --evaluate bob::bar::y hello ``` The format of exported variables may be controlled with `--evaluate-format`master: ``` $ just --evaluate --evaluate-format shell bar="world" foo="hello" ``` The default format is `--evaluate-format just`: ``` $ just --evaluate --evaluate-format just bar := "world" foo := "hello" ``` Expressions and Substitutions Various operators and function calls are supported in expressions, which may be used in assignments, default recipe arguments, and inside recipe body `{{ā€¦}}` substitutions. ``` tmpdir := `mktemp -d` version := "0.2.7" tardir := tmpdir / "awesomesauce-" + version tarball := tardir + ".tar.gz" config := quote(config_dir() / ".project-config") publish: rm -f {{tarball}} mkdir {{tardir}} cp README.md *.c {{ config }} {{tardir}} tar zcvf {{tarball}} {{tardir}} scp {{tarball}} me@server.com:release/ rm -rf {{tarball}} {{tardir}} ``` Concatenation The `+` operator returns the left-hand argument concatenated with the right-hand argument: ``` foobar := 'foo' + 'bar' ``` Logical Operators The logical operators `&&` and `||` can be used to coalesce string values1\.37.0, similar to Python's `and` and `or`. These operators consider the empty string `''` to be false, and all other strings to be true. These operators are currently unstable. The `&&` operator returns the empty string if the left-hand argument is the empty string, otherwise it returns the right-hand argument: ``` foo := '' && 'goodbye' # '' bar := 'hello' && 'goodbye' # 'goodbye' ``` The `||` operator returns the left-hand argument if it is non-empty, otherwise it returns the right-hand argument: ``` foo := '' || 'goodbye' # 'goodbye' bar := 'hello' || 'goodbye' # 'hello' ``` Joining Paths The `/` operator can be used to join two strings with a slash: ``` foo := "a" / "b" ``` ``` $ just --evaluate foo a/b ``` Note that a `/` is added even if one is already present: ``` foo := "a/" bar := foo / "b" ``` ``` $ just --evaluate bar a//b ``` Absolute paths can also be constructed1\.5.0: ``` foo := / "b" ``` ``` $ just --evaluate foo /b ``` The `/` operator uses the `/` character, even on Windows. Thus, using the `/` operator should be avoided with paths that use universal naming convention (UNC), i.e., those that start with `\?`, since forward slashes are not supported with UNC paths. Escaping `{{` To write a recipe containing `{{`, use `{{{{`: ``` braces: echo 'I {{{{LOVE}} curly braces!' ``` (An unmatched `}}` is ignored, so it doesn't need to be escaped.) Another option is to put all the text you'd like to escape inside of an interpolation: ``` braces: echo '{{'I {{LOVE}} curly braces!'}}' ``` Yet another option is to use `{{ "{{" }}`: ``` braces: echo 'I {{ "{{" }}LOVE}} curly braces!' ``` Strings `'single'`, `"double"`, and `'''triple'''` quoted string literals are supported. Unlike in recipe bodies, `{{ā€¦}}` interpolations are not supported inside strings. Double-quoted strings support escape sequences: ``` carriage-return := "\r" double-quote := "\"" newline := "\n" no-newline := "\ " slash := "\\" tab := "\t" unicode-codepoint := "\u{1F916}" ``` ``` $ just --evaluate "arriage-return := " double-quote := """ newline := " " no-newline := "" slash := "\" tab := " " unicode-codepoint := "šŸ¤–" ``` The unicode character escape sequence `\u{ā€¦}`1\.36.0 accepts up to six hex digits. Strings may contain line breaks: ``` single := ' hello ' double := " goodbye " ``` Single-quoted strings do not recognize escape sequences: ``` escapes := '\t\n\r\"\\' ``` ``` $ just --evaluate escapes := "\t\n\r\"\\" ``` Indented versions of both single- and double-quoted strings, delimited by triple single- or double-quotes, are supported. Indented string lines are stripped of a leading line break, and leading whitespace common to all non-blank lines: ``` # this string will evaluate to `foo\nbar\n` x := ''' foo bar ''' # this string will evaluate to `abc\n wuv\nxyz\n` y := """ abc wuv xyz """ ``` Similar to unindented strings, indented double-quoted strings process escape sequences, and indented single-quoted strings ignore escape sequences. Escape sequence processing takes place after unindentation. The unindentation algorithm does not take escape-sequence produced whitespace or newlines into account. Shell-expanded strings Strings prefixed with `x` are shell expanded1\.27.0: ``` foobar := x'~/$FOO/${BAR}' ``` | Value | Replacement | |---|---| | `$VAR` | value of environment variable `VAR` | | `${VAR}` | value of environment variable `VAR` | | `${VAR:-DEFAULT}` | value of environment variable `VAR`, or `DEFAULT` if `VAR` is not set | | Leading `~` | path to current user's home directory | | Leading `~USER` | path to `USER`'s home directory | This expansion is performed at compile time, so variables from `.env` files and exported `just` variables cannot be used. However, this allows shell expanded strings to be used in places like settings and import paths, which cannot depend on `just` variables and `.env` files. Format strings Strings prefixed with `f` are format strings1\.44.0: ``` name := "world" message := f'Hello, {{name}}!' ``` Format strings may contain interpolations delimited with `{{ā€¦}}` that contain expressions. Format strings evaluate to the concatenated string fragments and evaluated expressions. Use `{{{{` to include a literal `{{` in a format string: ``` foo := f'I {{{{LOVE} curly braces!' ``` Sigils Commands in linewise recipes may be prefixed with any combination of the sigils `-`, `@`, and `?`. The `@` sigil toggles command echoing: ``` foo: @echo "This line won't be echoed!" echo "This line will be echoed!" @bar: @echo "This line will be echoed!" echo "This line won't be echoed!" ``` The `-` sigil cause recipe execution to continue even if the command returns a nonzero exit status: ``` # execution will continue, even if bar doesn't exist foo: -rmdir bar mkdir bar echo 'so much good stuff' > bar/stuff.txt ``` The `?` sigil1\.47.0 causes the current recipe to stop executing if the command exits with status code `1`, however execution of other recipes will continue. Exit status `0` causes the current recipe to continue execution as normal. All other exit codes are reserved and should not be used, as they may be given meaning in a future version of `just`. If the `guards` setting is unset or false, `?` sigils are ignored and instead treated as part of the command. ``` set guards @foo: bar echo FOO @bar: ?[[ -f baz ]] echo BAR ``` ``` $ just foo FOO $ touch baz $ just foo BAR FOO ``` Functions `just` provides many built-in functions for use in expressions, including recipe body `{{ā€¦}}` substitutions, assignments, and default parameter values. All functions ending in `_directory` can be abbreviated to `_dir`. So `home_directory()` can also be written as `home_dir()`. In addition, `invocation_directory_native()` can be abbreviated to `invocation_dir_native()`. System Information - `arch()` ā€” Instruction set architecture. Possible values are: `"aarch64"`, `"arm"`, `"asmjs"`, `"hexagon"`, `"mips"`, `"msp430"`, `"powerpc"`, `"powerpc64"`, `"s390x"`, `"sparc"`, `"wasm32"`, `"x86"`, `"x86_64"`, and `"xcore"`. - `num_cpus()`1\.15.0 - Number of logical CPUs. - `os()` ā€” Operating system. Possible values are: `"android"`, `"bitrig"`, `"dragonfly"`, `"emscripten"`, `"freebsd"`, `"haiku"`, `"ios"`, `"linux"`, `"macos"`, `"netbsd"`, `"openbsd"`, `"solaris"`, and `"windows"`. - `os_family()` ā€” Operating system family; possible values are: `"unix"` and `"windows"`. For example: ``` system-info: @echo "This is an {{arch()}} machine". ``` ``` $ just system-info This is an x86_64 machine ``` The `os_family()` function can be used to create cross-platform `justfile`s that work on various operating systems. For an example, see [cross-platform.just](https://github.com/casey/just/blob/master/examples/cross-platform.just) file. External Commands - `shell(command, args...)`1\.27.0 returns the standard output of shell script `command` with zero or more positional arguments `args`. The shell used to interpret `command` is the same shell that is used to evaluate recipe lines, and can be changed with `set shell := [ā€¦]`. `command` is passed as the first argument, so if the command is `'echo $@'`, the full command line, with the default shell command `sh -cu` and `args` `'foo'` and `'bar'` will be: ``` 'sh' '-cu' 'echo $@' 'echo $@' 'foo' 'bar' ``` This is so that `$@` works as expected, and `$1` refers to the first argument. `$@` does not include the first positional argument, which is expected to be the name of the program being run. ``` # arguments can be variables or expressions file := '/sys/class/power_supply/BAT0/status' bat0stat := shell('cat $1', file) # commands can be variables or expressions command := 'wc -l' output := shell(command + ' "$1"', 'main.c') # arguments referenced by the shell command must be used empty := shell('echo', 'foo') full := shell('echo $1', 'foo') error := shell('echo $1') ``` ``` # Using python as the shell. Since `python -c` sets `sys.argv[0]` to `'-c'`, # the first "real" positional argument will be `sys.argv[2]`. set shell := ["python3", "-c"] olleh := shell('import sys; print(sys.argv[2][::-1])', 'hello') ``` Environment Variables - `env(key)`1\.15.0 ā€” Retrieves the environment variable with name `key`, aborting if it is not present. ``` home_dir := env('HOME') test: echo "{{home_dir}}" ``` ``` $ just /home/user1 ``` - `env(key, default)`1\.15.0 ā€” Retrieves the environment variable with name `key`, returning `default` if it is not present. - `env_var(key)` ā€” Deprecated alias for `env(key)`. - `env_var_or_default(key, default)` ā€” Deprecated alias for `env(key, default)`. A default can be substituted for an empty environment variable value with the `||` operator, currently unstable: ``` set unstable foo := env('FOO', '') || 'DEFAULT_VALUE' ``` Executables - `require(name)`1\.39.0 ā€” Search directories in the `PATH` environment variable for the executable `name` and return its full path, or halt with an error if no executable with `name` exists. ``` bash := require("bash") @test: echo "bash: '{{bash}}'" ``` ``` $ just bash: '/bin/bash' ``` - `which(name)`1\.39.0 ā€” Search directories in the `PATH` environment variable for the executable `name` and return its full path, or the empty string if no executable with `name` exists. Currently unstable. ``` set unstable bosh := which("bosh") @test: echo "bosh: '{{bosh}}'" ``` ``` $ just bosh: '' ``` Invocation Information - `is_dependency()` - Returns the string `true` if the current recipe is being run as a dependency of another recipe, rather than being run directly, otherwise returns the string `false`. Invocation Directory - `invocation_directory()` - Retrieves the absolute path to the current directory when `just` was invoked, before `just` changed it (chdir'd) prior to executing commands. On Windows, `invocation_directory()` uses `cygpath` to convert the invocation directory to a Cygwin-compatible `/`\-separated path. Use `invocation_directory_native()` to return the verbatim invocation directory on all platforms. For example, to call `rustfmt` on files just under the "current directory" (from the user/invoker's perspective), use the following rule: ``` rustfmt: find {{invocation_directory()}} -name \*.rs -exec rustfmt {} \; ``` Alternatively, if your command needs to be run from the current directory, you could use (e.g.): ``` build: cd {{invocation_directory()}}; ./some_script_that_needs_to_be_run_from_here ``` - `invocation_directory_native()` - Retrieves the absolute path to the current directory when `just` was invoked, before `just` changed it (chdir'd) prior to executing commands. Justfile and Justfile Directory - `justfile()` - Retrieves the path of the current `justfile`. - `justfile_directory()` - Retrieves the path of the parent directory of the current `justfile`. For example, to run a command relative to the location of the current `justfile`: ``` script: {{justfile_directory()}}/scripts/some_script ``` Source and Source Directory - `source_file()`1\.27.0 - Retrieves the path of the current source file. - `source_directory()`1\.27.0 - Retrieves the path of the parent directory of the current source file. `source_file()` and `source_directory()` behave the same as `justfile()` and `justfile_directory()` in the root `justfile`, but will return the path and directory, respectively, of the current `import` or `mod` source file when called from within an import or submodule. Module and Module Directory - `module_file()` - Retrieves the path of the current module file. - `module_directory()` - Retrieves the path of the parent directory of the current module file. `module_file()` and `module_directory()` behave the same as `justfile()` and `justfile_directory()` in the root `justfile`, but will return the path and directory, respectively, of the current `mod` source file when called from within submodule. Just Executable - `just_executable()` - Absolute path to the `just` executable. For example: ``` executable: @echo The executable is at: {{just_executable()}} ``` ``` $ just The executable is at: /bin/just ``` Just Process ID - `just_pid()` - Process ID of the `just` executable. For example: ``` pid: @echo The process ID is: {{ just_pid() }} ``` ``` $ just The process ID is: 420 ``` String Manipulation - `append(suffix, s)`1\.27.0 Append `suffix` to whitespace-separated strings in `s`. `append('/src', 'foo bar baz')` ā†’ `'foo/src bar/src baz/src'` - `prepend(prefix, s)`1\.27.0 Prepend `prefix` to whitespace-separated strings in `s`. `prepend('src/', 'foo bar baz')` ā†’ `'src/foo src/bar src/baz'` - `encode_uri_component(s)`1\.27.0 - Percent-encode characters in `s` except `[A-Za-z0-9_.!~*'()-]`, matching the behavior of the [JavaScript `encodeURIComponent` function](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/encodeURIComponent). - `quote(s)` - Replace all single quotes with `'\''` and prepend and append single quotes to `s`. This is sufficient to escape special characters for many shells, including most Bourne shell descendants. - `replace(s, from, to)` - Replace all occurrences of `from` in `s` with `to`. - `replace_regex(s, regex, replacement)` - Replace all occurrences of `regex` in `s` with `replacement`. Regular expressions are provided by the [Rust `regex` crate](https://docs.rs/regex/latest/regex/). See the [syntax documentation](https://docs.rs/regex/latest/regex/#syntax) for usage examples. Capture groups are supported. The `replacement` string uses [Replacement string syntax](https://docs.rs/regex/latest/regex/struct.Regex.html#replacement-string-syntax). - `trim(s)` - Remove leading and trailing whitespace from `s`. - `trim_end(s)` - Remove trailing whitespace from `s`. - `trim_end_match(s, substring)` - Remove suffix of `s` matching `substring`. - `trim_end_matches(s, substring)` - Repeatedly remove suffixes of `s` matching `substring`. - `trim_start(s)` - Remove leading whitespace from `s`. - `trim_start_match(s, substring)` - Remove prefix of `s` matching `substring`. - `trim_start_matches(s, substring)` - Repeatedly remove prefixes of `s` matching `substring`. Case Conversion - `capitalize(s)`1\.7.0 - Convert first character of `s` to uppercase and the rest to lowercase. - `kebabcase(s)`1\.7.0 - Convert `s` to `kebab-case`. - `lowercamelcase(s)`1\.7.0 - Convert `s` to `lowerCamelCase`. - `lowercase(s)` - Convert `s` to lowercase. - `shoutykebabcase(s)`1\.7.0 - Convert `s` to `SHOUTY-KEBAB-CASE`. - `shoutysnakecase(s)`1\.7.0 - Convert `s` to `SHOUTY_SNAKE_CASE`. - `snakecase(s)`1\.7.0 - Convert `s` to `snake_case`. - `titlecase(s)`1\.7.0 - Convert `s` to `Title Case`. - `uppercamelcase(s)`1\.7.0 - Convert `s` to `UpperCamelCase`. - `uppercase(s)` - Convert `s` to uppercase. Path Manipulation Fallible - `absolute_path(path)` - Absolute path to relative `path` in the working directory. `absolute_path("./bar.txt")` in directory `/foo` is `/foo/bar.txt`. - `canonicalize(path)`1\.24.0 - Canonicalize `path` by resolving symlinks and removing `.`, `..`, and extra `/`s where possible. - `extension(path)` - Extension of `path`. `extension("/foo/bar.txt")` is `txt`. - `file_name(path)` - File name of `path` with any leading directory components removed. `file_name("/foo/bar.txt")` is `bar.txt`. - `file_stem(path)` - File name of `path` without extension. `file_stem("/foo/bar.txt")` is `bar`. - `parent_directory(path)` - Parent directory of `path`. `parent_directory("/foo/bar.txt")` is `/foo`. - `without_extension(path)` - `path` without extension. `without_extension("/foo/bar.txt")` is `/foo/bar`. These functions can fail, for example if a path does not have an extension, which will halt execution. Infallible - `clean(path)` - Simplify `path` by removing extra path separators, intermediate `.` components, and `..` where possible. `clean("foo//bar")` is `foo/bar`, `clean("foo/..")` is `.`, `clean("foo/./bar")` is `foo/bar`. - `join(a, bā€¦)` - *This function uses `/` on Unix and `\` on Windows, which can be lead to unwanted behavior. The `/` operator, e.g., `a / b`, which always uses `/`, should be considered as a replacement unless `\`s are specifically desired on Windows.* Join path `a` with path `b`. `join("foo/bar", "baz")` is `foo/bar/baz`. Accepts two or more arguments. Filesystem Access - `path_exists(path)` - Returns the string `true` if the path points at an existing entity and the string `false` otherwise. Traverses symbolic links, and returns the string `false` if the path is inaccessible or points to a broken symlink. - `read(path)`1\.39.0 - Returns the content of file at `path` as string. Error Reporting - `error(message)` - Abort execution and report error `message` to user. UUID and Hash Generation - `blake3(string)`1\.25.0 - Return [BLAKE3](https://github.com/BLAKE3-team/BLAKE3/) hash of `string` as hexadecimal string. - `blake3_file(path)`1\.25.0 - Return [BLAKE3](https://github.com/BLAKE3-team/BLAKE3/) hash of file at `path` as hexadecimal string. - `sha256(string)` - Return the SHA-256 hash of `string` as hexadecimal string. - `sha256_file(path)` - Return SHA-256 hash of file at `path` as hexadecimal string. - `uuid()` - Generate a random version 4 UUID. Random - `choose(n, alphabet)`1\.27.0 - Generate a string of `n` randomly selected characters from `alphabet`, which may not contain repeated characters. For example, `choose('64', HEX)` will generate a random 64-character lowercase hex string. Datetime - `datetime(format)`1\.30.0 - Return local time with `format`. - `datetime_utc(format)`1\.30.0 - Return UTC time with `format`. The arguments to `datetime` and `datetime_utc` are `strftime`\-style format strings, see the [`chrono` library docs](https://docs.rs/chrono/latest/chrono/format/strftime/index.html) for details. Semantic Versions - `semver_matches(version, requirement)`1\.16.0 - Check whether a [semantic `version`](https://semver.org/), e.g., `"0.1.0"` matches a `requirement`, e.g., `">=0.1.0"`, returning the string `"true"` if so and the string `"false"` otherwise. Style - `style(name)`1\.37.0 - Return a named terminal display attribute escape sequence used by `just`. Unlike terminal display attribute escape sequence constants, which contain standard colors and styles, `style(name)` returns an escape sequence used by `just` itself, and can be used to make recipe output match `just`'s own output. Recognized values for `name` are `'command'`, for echoed recipe lines, `error`, and `warning`. For example, to style an error message: ``` scary: @echo '{{ style("error") }}OH NO{{ NORMAL }}' ``` User Directories These functions1\.23.0 return paths to user-specific directories for things like configuration, data, caches, executables, and the user's home directory. On Unix, these functions follow the [XDG Base Directory Specification](https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html). On MacOS and Windows, these functions return the system-specified user-specific directories. For example, `cache_directory()` returns `~/Library/Caches` on MacOS and `{FOLDERID_LocalAppData}` on Windows. See the [`dirs`](https://docs.rs/dirs/latest/dirs/index.html) crate for more details. - `cache_directory()` - The user-specific cache directory. - `config_directory()` - The user-specific configuration directory. - `config_local_directory()` - The local user-specific configuration directory. - `data_directory()` - The user-specific data directory. - `data_local_directory()` - The local user-specific data directory. - `executable_directory()` - The user-specific executable directory. - `home_directory()` - The user's home directory. If you would like to use XDG base directories on all platforms you can use the `env(ā€¦)` function with the appropriate environment variable and fallback, although note that the XDG specification requires ignoring non-absolute paths, so for full compatibility with spec-compliant applications, you would need to do: ``` xdg_config_dir := if env('XDG_CONFIG_HOME', '') =~ '^/' { env('XDG_CONFIG_HOME') } else { home_directory() / '.config' } ``` Constants A number of constants are predefined: | Name | Value | Value on Windows | |---|---|---| | `HEX`1\.27.0 | `"0123456789abcdef"` | | | `HEXLOWER`1\.27.0 | `"0123456789abcdef"` | | | `HEXUPPER`1\.27.0 | `"0123456789ABCDEF"` | | | `PATH_SEP`1\.41.0 | `"/"` | `"\"` | | `PATH_VAR_SEP`1\.41.0 | `":"` | `";"` | | `CLEAR`1\.37.0 | `"\ec"` | | | `NORMAL`1\.37.0 | `"\e[0m"` | | | `BOLD`1\.37.0 | `"\e[1m"` | | | `ITALIC`1\.37.0 | `"\e[3m"` | | | `UNDERLINE`1\.37.0 | `"\e[4m"` | | | `INVERT`1\.37.0 | `"\e[7m"` | | | `HIDE`1\.37.0 | `"\e[8m"` | | | `STRIKETHROUGH`1\.37.0 | `"\e[9m"` | | | `BLACK`1\.37.0 | `"\e[30m"` | | | `RED`1\.37.0 | `"\e[31m"` | | | `GREEN`1\.37.0 | `"\e[32m"` | | | `YELLOW`1\.37.0 | `"\e[33m"` | | | `BLUE`1\.37.0 | `"\e[34m"` | | | `MAGENTA`1\.37.0 | `"\e[35m"` | | | `CYAN`1\.37.0 | `"\e[36m"` | | | `WHITE`1\.37.0 | `"\e[37m"` | | | `BG_BLACK`1\.37.0 | `"\e[40m"` | | | `BG_RED`1\.37.0 | `"\e[41m"` | | | `BG_GREEN`1\.37.0 | `"\e[42m"` | | | `BG_YELLOW`1\.37.0 | `"\e[43m"` | | | `BG_BLUE`1\.37.0 | `"\e[44m"` | | | `BG_MAGENTA`1\.37.0 | `"\e[45m"` | | | `BG_CYAN`1\.37.0 | `"\e[46m"` | | | `BG_WHITE`1\.37.0 | `"\e[47m"` | | ``` @foo: echo {{HEX}} ``` ``` $ just foo 0123456789abcdef ``` Constants starting with `\e` are [ANSI escape sequences](https://en.wikipedia.org/wiki/ANSI_escape_code). `CLEAR` clears the screen, similar to the `clear` command. The rest are of the form `\e[Nm`, where `N` is an integer, and set terminal display attributes. Terminal display attribute escape sequences can be combined, for example text weight `BOLD`, text style `STRIKETHROUGH`, foreground color `CYAN`, and background color `BG_BLUE`. They should be followed by `NORMAL`, to reset the terminal back to normal. Escape sequences should be quoted, since `[` is treated as a special character by some shells. ``` @foo: echo '{{BOLD + STRIKETHROUGH + CYAN + BG_BLUE}}Hi!{{NORMAL}}' ``` Attributes Recipes, `mod` statements, and aliases may be annotated with attributes that change their behavior. | Name | Type | Description | |---|---|---| | `[arg(ARG, help="HELP")]`1\.46.0 | recipe | Print help string `HELP` for `ARG` in usage messages. | | `[arg(ARG, long="LONG")]`1\.46.0 | recipe | Require values of argument `ARG` to be passed as `--LONG` option. | | `[arg(ARG, pattern="PATTERN")]`1\.45.0 | recipe | Require values of argument `ARG` to match regular expression `PATTERN`. | | `[arg(ARG, short="S")]`1\.46.0 | recipe | Require values of argument `ARG` to be passed as short `-S` option. | | `[arg(ARG, value="VALUE")]`1\.46.0 | recipe | Makes option `ARG` a flag which does not take a value. | | `[confirm(PROMPT)]`1\.23.0 | recipe | Require confirmation prior to executing recipe with a custom prompt. | | `[confirm]`1\.17.0 | recipe | Require confirmation prior to executing recipe. | | `[default]`1\.43.0 | recipe | Use recipe as module's default recipe. | | `[doc(DOC)]`1\.27.0 | module, recipe | Set recipe or module's [documentation comment](https://github.com/casey/just#documentation-comments) to `DOC`. | | `[dragonfly]`1\.47.0 | recipe | Enable recipe on DragonFly BSD. | | `[env(ENV_VAR, VALUE)]` 1\.47.0 | recipe | Set environment variables for recipe. | | `[extension(EXT)]`1\.32.0 | recipe | Set shebang recipe script's file extension to `EXT`. `EXT` should include a period if one is desired. | | `[freebsd]`1\.47.0 | recipe | Enable recipe on FreeBSD. | | `[group(NAME)]`1\.27.0 | module, recipe | Put recipe or module in [group](https://github.com/casey/just#groups) `NAME`. | | `[linux]`1\.8.0 | recipe | Enable recipe on Linux. | | `[macos]`1\.8.0 | recipe | Enable recipe on MacOS. | | `[metadata(METADATA)]`1\.42.0 | recipe | Attach `METADATA` to recipe. | | `[netbsd]`1\.47.0 | recipe | Enable recipe on NetBSD. | | `[no-cd]`1\.9.0 | recipe | Don't change directory before executing recipe. | | `[no-exit-message]`1\.7.0 | recipe | Don't print an error message if recipe fails. | | `[no-quiet]`1\.23.0 | recipe | Override globally quiet recipes and always echo out the recipe. | | `[openbsd]`1\.38.0 | recipe | Enable recipe on OpenBSD. | | `[parallel]`1\.42.0 | recipe | Run this recipe's dependencies in parallel. | | `[positional-arguments]`1\.29.0 | recipe | Turn on [positional arguments](https://github.com/casey/just#positional-arguments) for this recipe. | | `[private]`1\.10.0 | alias, recipe | Make recipe, alias, or variable private. See [Private Recipes](https://github.com/casey/just#private-recipes). | | `[script(COMMAND)]`1\.32.0 | recipe | Execute recipe as a script interpreted by `COMMAND`. See [script recipes](https://github.com/casey/just#script-recipes) for more details. | | `[script]`1\.33.0 | recipe | Execute recipe as script. See [script recipes](https://github.com/casey/just#script-recipes) for more details. | | `[unix]`1\.8.0 | recipe | Enable recipe on Unixes. (Includes MacOS). | | `[windows]`1\.8.0 | recipe | Enable recipe on Windows. | | `[working-directory(PATH)]`1\.38.0 | recipe | Set recipe working directory. `PATH` may be relative or absolute. If relative, it is interpreted relative to the default working directory. | A recipe can have multiple attributes, either on multiple lines: ``` [no-cd] [private] foo: echo "foo" ``` Or separated by commas on a single line1\.14.0: ``` [no-cd, private] foo: echo "foo" ``` Attributes with a single argument may be written with a colon: ``` [group: 'bar'] foo: ``` Enabling and Disabling Recipes The `[linux]`, `[macos]`, `[unix]`, and `[windows]` attributes1\.8.0 are configuration attributes. By default, recipes are always enabled. A recipe with one or more configuration attributes will only be enabled when one or more of those configurations is active. This can be used to write `justfile`s that behave differently depending on which operating system they run on. The `run` recipe in this `justfile` will compile and run `main.c`, using a different C compiler and using the correct output binary name for that compiler depending on the operating system: ``` [unix] run: cc main.c ./a.out [windows] run: cl main.c main.exe ``` Disabling Changing Directory `just` normally executes recipes with the current directory set to the directory that contains the `justfile`. This can be disabled using the `[no-cd]` attribute1\.9.0. This can be used to create recipes which use paths relative to the invocation directory, or which operate on the current directory. For example, this `commit` recipe: ``` [no-cd] commit file: git add {{file}} git commit ``` Can be used with paths that are relative to the current directory, because `[no-cd]` prevents `just` from changing the current directory when executing `commit`. Requiring Confirmation for Recipes `just` normally executes all recipes unless there is an error. The `[confirm]` attribute1\.17.0 allows recipes require confirmation in the terminal prior to running. This can be overridden by passing `--yes` to `just`, which will automatically confirm any recipes marked by this attribute. Recipes dependent on a recipe that requires confirmation will not be run if the relied upon recipe is not confirmed, as well as recipes passed after any recipe that requires confirmation. ``` [confirm] delete-all: rm -rf * ``` Custom Confirmation Prompt The default confirmation prompt can be overridden with `[confirm(PROMPT)]`1\.23.0: ``` [confirm("Are you sure you want to delete everything?")] delete-everything: rm -rf * ``` Metadata Metadata in the form of lists of strings may be attached to recipes with the `[metadata(METADATA)]` attribute1\.42.0: ``` [metadata("hello", "goodbye")] foo: ``` Metadata can be read using `just --dump --dump-format json`. Groups Recipes and modules may be annotated with one or more group names: ``` [group('lint')] js-lint: echo 'Running JS linterā€¦' [group('rust recipes')] [group('lint')] rust-lint: echo 'Running Rust linterā€¦' [group('lint')] cpp-lint: echo 'Running C++ linterā€¦' # not in any group email-everyone: echo 'Sending mass emailā€¦' ``` Recipes are listed by group: ``` $ just --list Available recipes: email-everyone # not in any group [lint] cpp-lint js-lint rust-lint [rust recipes] rust-lint ``` `just --list --unsorted` prints recipes in their justfile order within each group: ``` $ just --list --unsorted Available recipes: (no group) email-everyone # not in any group [lint] js-lint rust-lint cpp-lint [rust recipes] rust-lint ``` Groups can be listed with `--groups`: ``` $ just --groups Recipe groups: lint rust recipes ``` Use `just --groups --unsorted` to print groups in their justfile order. Command Evaluation Using Backticks Backticks can be used to store the result of commands: ``` localhost := `dumpinterfaces | cut -d: -f2 | sed 's/\/.*//' | sed 's/ //g'` serve: ./serve {{localhost}} 8080 ``` Indented backticks, delimited by three backticks, are de-indented in the same manner as indented strings: ``` # This backtick evaluates the command `echo foo\necho bar\n`, which produces the value `foo\nbar\n`. stuff := ``` echo foo echo bar ``` ``` See the [Strings](https://github.com/casey/just#strings) section for details on unindenting. Backticks may not start with `#!`. This syntax is reserved for a future upgrade. The [`shell(ā€¦)` function](https://github.com/casey/just#external-commands) provides a more general mechanism to invoke external commands, including the ability to execute the contents of a variable as a command, and to pass arguments to a command. Conditional Expressions `if`/`else` expressions evaluate different branches depending on if two expressions evaluate to the same value: ``` foo := if "2" == "2" { "Good!" } else { "1984" } bar: @echo "{{foo}}" ``` ``` $ just bar Good! ``` It is also possible to test for inequality: ``` foo := if "hello" != "goodbye" { "xyz" } else { "abc" } bar: @echo {{foo}} ``` ``` $ just bar xyz ``` And match against regular expressions: ``` foo := if "hello" =~ 'hel+o' { "match" } else { "mismatch" } bar: @echo {{foo}} ``` ``` $ just bar match ``` Regular expressions are provided by the [regex crate](https://github.com/rust-lang/regex), whose syntax is documented on [docs.rs](https://docs.rs/regex/1.5.4/regex/#syntax). Since regular expressions commonly use backslash escape sequences, consider using single-quoted string literals, which will pass slashes to the regex parser unmolested. Conditional expressions short-circuit, which means they only evaluate one of their branches. This can be used to make sure that backtick expressions don't run when they shouldn't. ``` foo := if env_var("RELEASE") == "true" { `get-something-from-release-database` } else { "dummy-value" } ``` Conditionals can be used inside of recipes: ``` bar foo: echo {{ if foo == "bar" { "hello" } else { "goodbye" } }} ``` Multiple conditionals can be chained: ``` foo := if "hello" == "goodbye" { "xyz" } else if "a" == "a" { "abc" } else { "123" } bar: @echo {{foo}} ``` ``` $ just bar abc ``` Stopping execution with error Execution can be halted with the `error` function. For example: ``` foo := if "hello" == "goodbye" { "xyz" } else if "a" == "b" { "abc" } else { error("123") } ``` Which produce the following error when run: ``` error: Call to function `error` failed: 123 | 16 | error("123") ``` Setting Variables from the Command Line Variables can be overridden from the command line. ``` os := "linux" test: build ./test --test {{os}} build: ./build {{os}} ``` ``` $ just ./build linux ./test --test linux ``` Any number of arguments of the form `NAME=VALUE` can be passed before recipes: ``` $ just os=plan9 ./build plan9 ./test --test plan9 ``` Or you can use the `--set` flag: ``` $ just --set os bsd ./build bsd ./test --test bsd ``` Variables in submodules can be overridden using the `::`\-separated path to the variable. A variable named `bar` in a submodule named `foo` may be overridden with `foo::bar=VALUE` or `--set foo::bar VALUE`. Getting and Setting Environment Variables Exporting `just` Variables Assignments prefixed with the `export` keyword will be exported to recipes as environment variables: ``` export RUST_BACKTRACE := "1" test: # will print a stack trace if it crashes cargo test ``` Parameters prefixed with a `$` will be exported as environment variables: ``` test $RUST_BACKTRACE="1": # will print a stack trace if it crashes cargo test ``` You can also use the `[env(NAME, VALUE)]` attribute to export environment variables to a specific recipe: ``` [env("RUST_BACKTRACE", "1")] test: # will print a stack trace if it crashes cargo test ``` Exported variables and parameters are not exported to backticks in the same scope. ``` export WORLD := "world" # This backtick will fail with "WORLD: unbound variable" BAR := `echo hello $WORLD` ``` ``` # Running `just a foo` will fail with "A: unbound variable" a $A $B=`echo $A`: echo $A $B ``` When [export](https://github.com/casey/just#export) is set, all `just` variables are exported as environment variables. Unexporting Environment Variables Environment variables can be unexported with the `unexport keyword`1\.29.0: ``` unexport FOO @foo: echo $FOO ``` ``` $ export FOO=bar $ just foo sh: FOO: unbound variable ``` Getting Environment Variables from the environment Environment variables from the environment are passed automatically to the recipes. ``` print_home_folder: echo "HOME is: '${HOME}'" ``` ``` $ just HOME is '/home/myuser' ``` Setting `just` Variables from Environment Variables Environment variables can be propagated to `just` variables using the `env()` function. See [environment-variables](https://github.com/casey/just#environment-variables). Recipe Parameters Recipes may have parameters. Here recipe `build` has a parameter called `target`: ``` build target: @echo 'Building {{target}}ā€¦' cd {{target}} && make ``` To pass arguments on the command line, put them after the recipe name: ``` $ just build my-awesome-project Building my-awesome-projectā€¦ cd my-awesome-project && make ``` To pass arguments to a dependency, put the dependency in parentheses along with the arguments: ``` default: (build "main") build target: @echo 'Building {{target}}ā€¦' cd {{target}} && make ``` Variables can also be passed as arguments to dependencies: ``` target := "main" _build version: @echo 'Building {{version}}ā€¦' cd {{version}} && make build: (_build target) ``` A command's arguments can be passed to dependency by putting the dependency in parentheses along with the arguments: ``` build target: @echo "Building {{target}}ā€¦" push target: (build target) @echo 'Pushing {{target}}ā€¦' ``` Parameters may have default values: ``` default := 'all' test target tests=default: @echo 'Testing {{target}}:{{tests}}ā€¦' ./test --tests {{tests}} {{target}} ``` Parameters with default values may be omitted: ``` $ just test server Testing server:allā€¦ ./test --tests all server ``` Or supplied: ``` $ just test server unit Testing server:unitā€¦ ./test --tests unit server ``` Default values may be arbitrary expressions, but expressions containing the `+`, `&&`, `||`, or `/` operators must be parenthesized: ``` arch := "wasm" test triple=(arch + "-unknown-unknown") input=(arch / "input.dat"): ./test {{triple}} ``` The last parameter of a recipe may be variadic, indicated with either a `+` or a `*` before the argument name: ``` backup +FILES: scp {{FILES}} me@server.com: ``` Variadic parameters prefixed with `+` accept *one or more* arguments and expand to a string containing those arguments separated by spaces: ``` $ just backup FAQ.md GRAMMAR.md scp FAQ.md GRAMMAR.md me@server.com: FAQ.md 100% 1831 1.8KB/s 00:00 GRAMMAR.md 100% 1666 1.6KB/s 00:00 ``` Variadic parameters prefixed with `*` accept *zero or more* arguments and expand to a string containing those arguments separated by spaces, or an empty string if no arguments are present: ``` commit MESSAGE *FLAGS: git commit {{FLAGS}} -m "{{MESSAGE}}" ``` Variadic parameters can be assigned default values. These are overridden by arguments passed on the command line: ``` test +FLAGS='-q': cargo test {{FLAGS}} ``` `{{ā€¦}}` substitutions may need to be quoted if they contain spaces. For example, if you have the following recipe: ``` search QUERY: lynx https://www.google.com/?q={{QUERY}} ``` And you type: ``` $ just search "cat toupee" ``` `just` will run the command `lynx https://www.google.com/?q=cat toupee`, which will get parsed by `sh` as `lynx`, `https://www.google.com/?q=cat`, and `toupee`, and not the intended `lynx` and `https://www.google.com/?q=cat toupee`. You can fix this by adding quotes: ``` search QUERY: lynx 'https://www.google.com/?q={{QUERY}}' ``` Parameters prefixed with a `$` will be exported as environment variables: ``` foo $bar: echo $bar ``` Parameters may be constrained to match regular expression patterns using the `[arg("name", pattern="pattern")]` attribute1\.45.0: ``` [arg('n', pattern='\d+')] double n: echo $(({{n}} * 2)) ``` A leading `^` and trailing `$` are added to the pattern, so it must match the entire argument value. You may constrain the pattern to a number of alternatives using the `|` operator: ``` [arg('flag', pattern='--help|--version')] info flag: just {{flag}} ``` Regular expressions are provided by the [Rust `regex` crate](https://docs.rs/regex/latest/regex/). See the [syntax documentation](https://docs.rs/regex/latest/regex/#syntax) for usage examples. Usage information for a recipe may be printed with the `--usage` subcommand1\.46.0: ``` $ just --usage foo Usage: just foo [OPTIONS] bar Arguments: bar ``` Help strings may be added to arguments using the `[arg(ARG, help=HELP)]` attribute: ``` [arg("bar", help="hello")] foo bar: ``` ``` $ just --usage foo Usage: just foo bar Arguments: bar hello ``` Recipe Flags and Options Recipe parameters are positional by default. In this `justfile`: ``` @foo bar: echo bar={{bar}} ``` The parameter `bar` is positional: ``` $ just foo hello bar=hello ``` The `[arg(ARG, long=OPTION)]`1\.46.0 attribute can be used to make a parameter a long option. In this `justfile`: ``` [arg("bar", long="bar")] foo bar: ``` The parameter `bar` is given with the `--bar` option: ``` $ just foo --bar hello bar=hello ``` Options may also be passed with `--name=value` syntax: ``` $ just foo --bar=hello bar=hello ``` The value of `long` can be omitted, in which case the option defaults to the name of the parameter: ``` [arg("bar", long)] foo bar: ``` The `[arg(ARG, short=OPTION)]`1\.46.0 attribute can be used to make a parameter a short option. In this `justfile`: ``` [arg("bar", short="b")] foo bar: ``` The parameter `bar` is given with the `-b` option: ``` $ just foo -b hello bar=hello ``` If a parameter has both a long and short option, it may be passed using either. Variadic `*` and `+` parameters cannot be options. The `[arg(ARG, value=VALUE, ā€¦)]`1\.46.0 attribute can be used with `long` or `short` to make a parameter a flag which does not take a value. In this `justfile`: ``` [arg("bar", long="bar", value="hello")] foo bar: ``` The parameter `bar` is given with the `--bar` option, but does not take a value, and instead takes the value given in the `[arg]` attribute: ``` $ just foo --bar bar=hello ``` This is useful for unconditionally requiring a flag like `--force` on dangerous commands. A flag is optional if its parameter has a default: ``` [arg("bar", long="bar", value="hello")] foo bar="goodbye": ``` Causing it to receive the default when not passed in the invocation: ``` $ just foo bar=goodbye ``` Dependencies Dependencies run before recipes that depend on them: ``` a: b @echo A b: @echo B ``` ``` $ just a B A ``` In a given invocation of `just`, a recipe with the same arguments will only run once, regardless of how many times it appears in the command-line invocation, or how many times it appears as a dependency: ``` a: @echo A b: a @echo B c: a @echo C ``` ``` $ just a a a a a A $ just b c A B C ``` Multiple recipes may depend on a recipe that performs some kind of setup, and when those recipes run, that setup will only be performed once: ``` build: cc main.c test-foo: build ./a.out --test foo test-bar: build ./a.out --test bar ``` ``` $ just test-foo test-bar cc main.c ./a.out --test foo ./a.out --test bar ``` Recipes in a given run are only skipped when they receive the same arguments: ``` build: cc main.c test TEST: build ./a.out --test {{TEST}} ``` ``` $ just test foo test bar cc main.c ./a.out --test foo ./a.out --test bar ``` Running Recipes at the End of a Recipe Normal dependencies of a recipes always run before a recipe starts. That is to say, the dependee always runs before the depender. These dependencies are called "prior dependencies". A recipe can also have subsequent dependencies, which run immediately after the recipe and are introduced with an `&&`: ``` a: echo 'A!' b: a && c d echo 'B!' c: echo 'C!' d: echo 'D!' ``` ā€¦running *b* prints: ``` $ just b echo 'A!' A! echo 'B!' B! echo 'C!' C! echo 'D!' D! ``` Running Recipes in the Middle of a Recipe `just` doesn't support running recipes in the middle of another recipe, but you can call `just` recursively in the middle of a recipe. Given the following `justfile`: ``` a: echo 'A!' b: a echo 'B start!' just c echo 'B end!' c: echo 'C!' ``` ā€¦running *b* prints: ``` $ just b echo 'A!' A! echo 'B start!' B start! echo 'C!' C! echo 'B end!' B end! ``` This has limitations, since recipe `c` is run with an entirely new invocation of `just`: Assignments will be recalculated, dependencies might run twice, and command line arguments will not be propagated to the child `just` process. Shebang Recipes Recipes that start with `#!` are called shebang recipes, and are executed by saving the recipe body to a file and running it. This lets you write recipes in different languages: ``` polyglot: python js perl sh ruby nu python: #!/usr/bin/env python3 print('Hello from python!') js: #!/usr/bin/env node console.log('Greetings from JavaScript!') perl: #!/usr/bin/env perl print "Larry Wall says Hi!\n"; sh: #!/usr/bin/env sh hello='Yo' echo "$hello from a shell script!" nu: #!/usr/bin/env nu let hello = 'Hola' echo $"($hello) from a nushell script!" ruby: #!/usr/bin/env ruby puts "Hello from ruby!" ``` ``` $ just polyglot Hello from python! Greetings from JavaScript! Larry Wall says Hi! Yo from a shell script! Hola from a nushell script! Hello from ruby! ``` On Unix-like operating systems, including Linux and MacOS, shebang recipes are executed by saving the recipe body to a file in a temporary directory, marking the file as executable, and executing it. The OS then parses the shebang line into a command line and invokes it, including the path to the file. For example, if a recipe starts with `#!/usr/bin/env bash`, the final command that the OS runs will be something like `/usr/bin/env bash /tmp/PATH_TO_SAVED_RECIPE_BODY`. Shebang line splitting is operating system dependent. When passing a command with arguments, you may need to tell `env` to split them explicitly by using the `-S` flag: ``` run: #!/usr/bin/env -S bash -x ls ``` Windows does not support shebang lines. On Windows, `just` splits the shebang line into a command and arguments, saves the recipe body to a file, and invokes the split command and arguments, adding the path to the saved recipe body as the final argument. For example, on Windows, if a recipe starts with `#! py`, the final command the OS runs will be something like `py C:\Temp\PATH_TO_SAVED_RECIPE_BODY`. Script Recipes Recipes with a `[script(COMMAND)]`1\.32.0 attribute are run as scripts interpreted by `COMMAND`. This avoids some of the issues with shebang recipes, such as the use of `cygpath` on Windows, the need to use `/usr/bin/env`, inconsistencies in shebang line splitting across Unix OSs, and requiring a temporary directory from which files can be executed. Recipes with an empty `[script]` attribute are executed with the value of `set script-interpreter := [ā€¦]`1\.33.0, defaulting to `sh -eu`, and *not* the value of `set shell`. The body of the recipe is evaluated, written to disk in the temporary directory, and run by passing its path as an argument to `COMMAND`. Script and Shebang Recipe Temporary Files Both script and shebang recipes write the recipe body to a temporary file for execution. Script recipes execute that file by passing it to a command, while shebang recipes execute the file directly. Shebang recipe execution will fail if the filesystem containing the temporary file is mounted with `noexec` or is otherwise non-executable. The directory that `just` writes temporary files to may be configured in a number of ways, from highest to lowest precedence: - Globally with the `--tempdir` command-line option or the `JUST_TEMPDIR` environment variable1\.41.0. - On a per-module basis with the `tempdir` setting. - Globally on Linux with the `XDG_RUNTIME_DIR` environment variable. - Falling back to the directory returned by [std::env::temp\_dir](https://doc.rust-lang.org/std/env/fn.temp_dir.html). Python Recipes with `uv` [`uv`](https://github.com/astral-sh/uv) is an excellent cross-platform python project manager, written in Rust. Using the `[script]` attribute and `script-interpreter` setting, `just` can easily be configured to run Python recipes with `uv`: ``` set script-interpreter := ['uv', 'run', '--script'] [script] hello: print("Hello from Python!") [script] goodbye: # /// script # requires-python = ">=3.11" # dependencies=["sh"] # /// import sh print(sh.echo("Goodbye from Python!"), end='') ``` Of course, a shebang also works: ``` hello: #!/usr/bin/env -S uv run --script print("Hello from Python!") ``` Safer Bash Shebang Recipes If you're writing a `bash` shebang recipe, consider adding `set -euxo pipefail`: ``` foo: #!/usr/bin/env bash set -euxo pipefail hello='Yo' echo "$hello from Bash!" ``` It isn't strictly necessary, but `set -euxo pipefail` turns on a few useful features that make `bash` shebang recipes behave more like normal, linewise `just` recipe: - `set -e` makes `bash` exit if a command fails. - `set -u` makes `bash` exit if a variable is undefined. - `set -x` makes `bash` print each script line before it's run. - `set -o pipefail` makes `bash` exit if a command in a pipeline fails. This is `bash`\-specific, so isn't turned on in normal linewise `just` recipes. Together, these avoid a lot of shell scripting gotchas. Shebang Recipe Execution on Windows On Windows, shebang interpreter paths containing a `/` are translated from Unix-style paths to Windows-style paths using `cygpath`, a utility that ships with [Cygwin](http://www.cygwin.com/). For example, to execute this recipe on Windows: ``` echo: #!/bin/sh echo "Hello!" ``` The interpreter path `/bin/sh` will be translated to a Windows-style path using `cygpath` before being executed. If the interpreter path does not contain a `/` it will be executed without being translated. This is useful if `cygpath` is not available, or you wish to pass a Windows-style path to the interpreter. Setting Variables in a Recipe Recipe lines are interpreted by the shell, not `just`, so it's not possible to set `just` variables in the middle of a recipe: ``` foo: x := "hello" # This doesn't work! echo {{x}} ``` It is possible to use shell variables, but there's another problem. Every recipe line is run by a new shell instance, so variables set in one line won't be set in the next: ``` foo: x=hello && echo $x # This works! y=bye echo $y # This doesn't, `y` is undefined here! ``` The best way to work around this is to use a shebang recipe. Shebang recipe bodies are extracted and run as scripts, so a single shell instance will run the whole thing: ``` foo: #!/usr/bin/env bash set -euxo pipefail x=hello echo $x ``` Sharing Environment Variables Between Recipes Each line of each recipe is executed by a fresh shell, so it is not possible to share environment variables between recipes. Using Python Virtual Environments Some tools, like [Python's venv](https://docs.python.org/3/library/venv.html), require loading environment variables in order to work, making them challenging to use with `just`. As a workaround, you can execute the virtual environment binaries directly: ``` venv: [ -d foo ] || python3 -m venv foo run: venv ./foo/bin/python3 main.py ``` Changing the Working Directory in a Recipe Each recipe line is executed by a new shell, so if you change the working directory on one line, it won't have an effect on later lines: ``` foo: pwd # This `pwd` will print the same directoryā€¦ cd bar pwd # ā€¦as this `pwd`! ``` There are a couple ways around this. One is to call `cd` on the same line as the command you want to run: ``` foo: cd bar && pwd ``` The other is to use a shebang recipe. Shebang recipe bodies are extracted and run as scripts, so a single shell instance will run the whole thing, and thus a `cd` on one line will affect later lines, just like a shell script: ``` foo: #!/usr/bin/env bash set -euxo pipefail cd bar pwd ``` Indentation Recipe lines can be indented with spaces or tabs, but not a mix of both. All of a recipe's lines must have the same type of indentation, but different recipes in the same `justfile` may use different indentation. Each recipe must be indented at least one level from the `recipe-name` but after that may be further indented. Here's a justfile with a recipe indented with spaces, represented as `Ā·`, and tabs, represented as `ā†’`. ``` set windows-shell := ["pwsh", "-NoLogo", "-NoProfileLoadTime", "-Command"] set ignore-comments list-space directory: Ā·Ā·#!pwsh Ā·Ā·foreach ($item in $(Get-ChildItem {{directory}} )) { Ā·Ā·Ā·Ā·echo $item.Name Ā·Ā·} Ā·Ā·echo "" # indentation nesting works even when newlines are escaped list-tab directory: ā†’ @foreach ($item in $(Get-ChildItem {{directory}} )) { \ ā†’ ā†’ echo $item.Name \ ā†’ } ā†’ @echo "" ``` ``` PS > just list-space ~ Desktop Documents Downloads PS > just list-tab ~ Desktop Documents Downloads ``` Multi-Line Constructs Recipes without an initial shebang are evaluated and run line-by-line, which means that multi-line constructs probably won't do what you want. For example, with the following `justfile`: ``` conditional: if true; then echo 'True!' fi ``` The extra leading whitespace before the second line of the `conditional` recipe will produce a parse error: ``` $ just conditional error: Recipe line has extra leading whitespace | 3 | echo 'True!' | ^^^^^^^^^^^^^^^^ ``` To work around this, you can write conditionals on one line, escape newlines with slashes, or add a shebang to your recipe. Some examples of multi-line constructs are provided for reference. `if` statements ``` conditional: if true; then echo 'True!'; fi ``` ``` conditional: if true; then \ echo 'True!'; \ fi ``` ``` conditional: #!/usr/bin/env sh if true; then echo 'True!' fi ``` `for` loops ``` for: for file in `ls .`; do echo $file; done ``` ``` for: for file in `ls .`; do \ echo $file; \ done ``` ``` for: #!/usr/bin/env sh for file in `ls .`; do echo $file done ``` `while` loops ``` while: while `server-is-dead`; do ping -c 1 server; done ``` ``` while: while `server-is-dead`; do \ ping -c 1 server; \ done ``` ``` while: #!/usr/bin/env sh while `server-is-dead`; do ping -c 1 server done ``` Outside Recipe Bodies Parenthesized expressions can span multiple lines: ``` abc := ('a' + 'b' + 'c') abc2 := ( 'a' + 'b' + 'c' ) foo param=('foo' + 'bar' ): echo {{param}} bar: (foo 'Foo' ) echo 'Bar!' ``` Lines ending with a backslash continue on to the next line as if the lines were joined by whitespace1\.15.0: ``` a := 'foo' + \ 'bar' foo param1 \ param2='foo' \ *varparam='': dep1 \ (dep2 'foo') echo {{param1}} {{param2}} {{varparam}} dep1: \ # this comment is not part of the recipe body echo 'dep1' dep2 \ param: echo 'Dependency with parameter {{param}}' ``` Backslash line continuations can also be used in interpolations. The line following the backslash must be indented. ``` recipe: echo '{{ \ "This interpolation " + \ "has a lot of text." \ }}' echo 'back to recipe body' ``` Command-line Options `just` supports a number of useful command-line options for listing, dumping, and debugging recipes and variables: ``` $ just --list Available recipes: js perl polyglot python ruby $ just --show perl perl: #!/usr/bin/env perl print "Larry Wall says Hi!\n"; $ just --show polyglot polyglot: python js perl sh ruby ``` Setting Command-line Options with Environment Variables Some command-line options can be set with environment variables For example, unstable features can be enabled either with the `--unstable` flag: ``` $ just --unstable ``` Or by setting the `JUST_UNSTABLE` environment variable: ``` $ export JUST_UNSTABLE=1 $ just ``` Since environment variables are inherited by child processes, command-line options set with environment variables are inherited by recursive invocations of `just`, where as command line options set with arguments are not. Consult `just --help` for which options can be set with environment variables. Private Recipes Recipes and aliases whose name starts with a `_` are omitted from `just --list`: ``` test: _test-helper ./bin/test _test-helper: ./bin/super-secret-test-helper-stuff ``` ``` $ just --list Available recipes: test ``` And from `just --summary`: ``` $ just --summary test ``` The `[private]` attribute1\.10.0 may also be used to hide recipes or aliases without needing to change the name: ``` [private] foo: [private] alias b := bar bar: ``` ``` $ just --list Available recipes: bar ``` This is useful for helper recipes which are only meant to be used as dependencies of other recipes. Quiet Recipes A recipe name may be prefixed with `@` to invert the meaning of `@` before each line: ``` @quiet: echo hello echo goodbye @# all done! ``` Now only the lines starting with `@` will be echoed: ``` $ just quiet hello goodbye # all done! ``` All recipes in a Justfile can be made quiet with `set quiet`: ``` set quiet foo: echo "This is quiet" @foo2: echo "This is also quiet" ``` The `[no-quiet]` attribute overrides this setting: ``` set quiet foo: echo "This is quiet" [no-quiet] foo2: echo "This is not quiet" ``` Shebang recipes are quiet by default: ``` foo: #!/usr/bin/env bash echo 'Foo!' ``` ``` $ just foo Foo! ``` Adding `@` to a shebang recipe name makes `just` print the recipe before executing it: ``` @bar: #!/usr/bin/env bash echo 'Bar!' ``` ``` $ just bar #!/usr/bin/env bash echo 'Bar!' Bar! ``` `just` normally prints error messages when a recipe line fails. These error messages can be suppressed using the `[no-exit-message]`1\.7.0 attribute. You may find this especially useful with a recipe that wraps a tool: ``` git *args: @git {{args}} ``` ``` $ just git status fatal: not a git repository (or any of the parent directories): .git error: Recipe `git` failed on line 2 with exit code 128 ``` Add the attribute to suppress the exit error message when the tool exits with a non-zero code: ``` [no-exit-message] git *args: @git {{args}} ``` ``` $ just git status fatal: not a git repository (or any of the parent directories): .git ``` Selecting Recipes to Run With an Interactive Chooser The `--choose` subcommand makes `just` invoke a chooser to select which recipes to run. Choosers should read lines containing recipe names from standard input and print one or more of those names separated by spaces to standard output. Because there is currently no way to run a recipe that requires arguments with `--choose`, such recipes will not be given to the chooser. Private recipes and aliases are also skipped. The chooser can be overridden with the `--chooser` flag. If `--chooser` is not given, then `just` first checks if `$JUST_CHOOSER` is set. If it isn't, then the chooser defaults to `fzf`, a popular fuzzy finder. Arguments can be included in the chooser, i.e. `fzf --exact`. The chooser is invoked in the same way as recipe lines. For example, if the chooser is `fzf`, it will be invoked with `sh -cu 'fzf'`, and if the shell, or the shell arguments are overridden, the chooser invocation will respect those overrides. If you'd like `just` to default to selecting recipes with a chooser, you can use this as your default recipe: ``` default: @just --choose ``` Invoking `justfile`s in Other Directories If the first argument passed to `just` contains a `/`, then the following occurs: 1. The argument is split at the last `/`. 2. The part before the last `/` is treated as a directory. `just` will start its search for the `justfile` there, instead of in the current directory. 3. The part after the last slash is treated as a normal argument, or ignored if it is empty. This may seem a little strange, but it's useful if you wish to run a command in a `justfile` that is in a subdirectory. For example, if you are in a directory which contains a subdirectory named `foo`, which contains a `justfile` with the recipe `build`, which is also the default recipe, the following are all equivalent: ``` $ (cd foo && just build) $ just foo/build $ just foo/ ``` Additional recipes after the first are sought in the same `justfile`. For example, the following are both equivalent: ``` $ just foo/a b $ (cd foo && just a b) ``` And will both invoke recipes `a` and `b` in `foo/justfile`. Imports One `justfile` can include the contents of another using `import` statements. If you have the following `justfile`: ``` import 'foo/bar.just' a: b @echo A ``` And the following text in `foo/bar.just`: ``` b: @echo B ``` `foo/bar.just` will be included in `justfile` and recipe `b` will be defined: ``` $ just b B $ just a B A ``` The `import` path can be absolute or relative to the location of the justfile containing it. A leading `~/` in the import path is replaced with the current users home directory. Justfiles are insensitive to order, so included files can reference variables and recipes defined after the `import` statement. Imported files can themselves contain `import`s, which are processed recursively. `allow-duplicate-recipes` and `allow-duplicate-variables` allow duplicate recipes and variables, respectively, to override each other, instead of producing an error. Within a module, later definitions override earlier definitions: ``` set allow-duplicate-recipes foo: foo: echo 'yes' ``` When `import`s are involved, things unfortunately get much more complicated and hard to explain. Shallower definitions always override deeper definitions, so recipes at the top level will override recipes in imports, and recipes in an import will override recipes in an import which itself imports those recipes. When two duplicate definitions are imported and are at the same depth, the one from the earlier import will override the one from the later import. This is because `just` uses a stack when processing imports, pushing imports onto the stack in source-order, and always processing the top of the stack next, so earlier imports are actually handled later by the compiler. This is definitely a bug, but since `just` has very strong backwards compatibility guarantees and we take enormous pains not to break anyone's `justfile`, we have created issue \#2540 to discuss whether or not we can actually fix it. Imports may be made optional by putting a `?` after the `import` keyword: ``` import? 'foo/bar.just' ``` Importing the same source file multiple times is not an error1\.37.0. This allows importing multiple justfiles, for example `foo.just` and `bar.just`, which both import a third justfile containing shared recipes, for example `baz.just`, without the duplicate import of `baz.just` being an error: ``` # justfile import 'foo.just' import 'bar.just' ``` ``` # foo.just import 'baz.just' foo: baz ``` ``` # bar.just import 'baz.just' bar: baz ``` ``` # baz baz: ``` Modules A `justfile` can declare modules using `mod` statements1\.19.0. `mod` statements were stabilized in `just`1\.31.0. If you have the following `justfile`: ``` mod bar a: @echo A ``` And the following text in `bar.just`: ``` b: @echo B ``` `bar.just` will be included in `justfile` as a submodule. Recipes, aliases, and variables defined in one submodule cannot be used in another, and each module uses its own settings. Recipes in submodules can be invoked as subcommands: ``` $ just bar b B ``` Or with path syntax: ``` $ just bar::b B ``` If a module is named `foo`, just will search for the module file in `foo.just`, `foo/mod.just`, `foo/justfile`, and `foo/.justfile`. In the latter two cases, the module file may have any capitalization. Module statements may be of the form: ``` mod foo 'PATH' ``` Which loads the module's source file from `PATH`, instead of from the usual locations. A leading `~/` in `PATH` is replaced with the current user's home directory. `PATH` may point to the module source file itself, or to a directory containing the module source file with the name `mod.just`, `justfile`, or `.justfile`. In the latter two cases, the module file may have any capitalization. Environment files are only loaded for the root justfile, and loaded environment variables are available in submodules. Settings in submodules that affect environment file loading are ignored. Recipes in submodules without the `[no-cd]` attribute run with the working directory set to the directory containing the submodule source file. `justfile()` and `justfile_directory()` always return the path to the root justfile and the directory that contains it, even when called from submodule recipes. Modules may be made optional by putting a `?` after the `mod` keyword: ``` mod? foo ``` Missing source files for optional modules do not produce an error. Optional modules with no source file do not conflict, so you can have multiple mod statements with the same name, but with different source file paths, as long as at most one source file exists: ``` mod? foo 'bar.just' mod? foo 'baz.just' ``` Modules may be given doc comments which appear in `--list` output1\.30.0: ``` # foo is a great module! mod foo ``` ``` $ just --list Available recipes: foo ... # foo is a great module! ``` Modules are still missing a lot of features, for example, the ability to refer to variables in other modules. See the [module improvement tracking issue](https://github.com/casey/just/issues/2252) for more information. Hiding `justfile`s `just` looks for `justfile`s named `justfile` and `.justfile`, which can be used to keep a `justfile` hidden. Just Scripts By adding a shebang line to the top of a `justfile` and making it executable, `just` can be used as an interpreter for scripts: ``` $ cat > script <<EOF #!/usr/bin/env just --justfile foo: echo foo EOF $ chmod +x script $ ./script foo echo foo foo ``` When a script with a shebang is executed, the system supplies the path to the script as an argument to the command in the shebang. So, with a shebang of `#!/usr/bin/env just --justfile`, the command will be `/usr/bin/env just --justfile PATH_TO_SCRIPT`. With the above shebang, `just` will change its working directory to the location of the script. If you'd rather leave the working directory unchanged, use `#!/usr/bin/env just --working-directory . --justfile`. Note: Shebang line splitting is not consistent across operating systems. The previous examples have only been tested on macOS. On Linux, you may need to pass the `-S` flag to `env`: ``` #!/usr/bin/env -S just --justfile default: echo foo ``` Formatting and dumping `justfile`s Each `justfile` has a canonical formatting with respect to whitespace and newlines. You can overwrite the current justfile with a canonically-formatted version using the currently-unstable `--fmt` flag: ``` $ cat justfile # A lot of blank lines some-recipe: echo "foo" $ just --fmt --unstable $ cat justfile # A lot of blank lines some-recipe: echo "foo" ``` Invoking `just --fmt --check --unstable` runs `--fmt` in check mode. Instead of overwriting the `justfile`, `just` will exit with an exit code of 0 if it is formatted correctly, and will exit with 1 and print a diff if it is not. You can use the `--dump` command to output a formatted version of the `justfile` to stdout: ``` $ just --dump > formatted-justfile ``` The `--dump` command can be used with `--dump-format json` to print a JSON representation of a `justfile`. Fallback to parent `justfile`s If a recipe is not found in a `justfile` and the `fallback` setting is set, `just` will look for `justfile`s in the parent directory and up, until it reaches the root directory. `just` will stop after it reaches a `justfile` in which the `fallback` setting is `false` or unset. As an example, suppose the current directory contains this `justfile`: ``` set fallback foo: echo foo ``` And the parent directory contains this `justfile`: ``` bar: echo bar ``` ``` $ just bar Trying ../justfile echo bar bar ``` Avoiding Argument Splitting Given this `justfile`: ``` foo argument: touch {{argument}} ``` The following command will create two files, `some` and `argument.txt`: ``` $ just foo "some argument.txt" ``` The user's shell will parse `"some argument.txt"` as a single argument, but when `just` replaces `touch {{argument}}` with `touch some argument.txt`, the quotes are not preserved, and `touch` will receive two arguments. There are a few ways to avoid this: quoting, positional arguments, and exported arguments. Quoting Quotes can be added around the `{{argument}}` interpolation: ``` foo argument: touch '{{argument}}' ``` This preserves `just`'s ability to catch variable name typos before running, for example if you were to write `{{argument}}`, but will not do what you want if the value of `argument` contains single quotes. Positional Arguments The `positional-arguments` setting causes all arguments to be passed as positional arguments, allowing them to be accessed with `$1`, `$2`, ā€¦, and `$@`, which can be then double-quoted to avoid further splitting by the shell: ``` set positional-arguments foo argument: touch "$1" ``` This defeats `just`'s ability to catch typos, for example if you type `$2` instead of `$1`, but works for all possible values of `argument`, including those with double quotes. Exported Arguments All arguments are exported when the `export` setting is set: ``` set export foo argument: touch "$argument" ``` Or individual arguments may be exported by prefixing them with `$`: ``` foo $argument: touch "$argument" ``` This defeats `just`'s ability to catch typos, for example if you type `$argument`, but works for all possible values of `argument`, including those with double quotes. Configuring the Shell There are a number of ways to configure the shell for linewise recipes, which are the default when a recipe does not start with a `#!` shebang. Their precedence, from highest to lowest, is: 1. The `--shell` and `--shell-arg` command line options. Passing either of these will cause `just` to ignore any settings in the current justfile. 2. `set windows-shell := [...]` 3. `set windows-powershell` (deprecated) 4. `set shell := [...]` Since `set windows-shell` has higher precedence than `set shell`, you can use `set windows-shell` to pick a shell on Windows, and `set shell` to pick a shell for all other platforms. Timestamps `just` can print timestamps before each recipe commands: ``` recipe: echo one sleep 2 echo two ``` ``` $ just --timestamp recipe [07:28:46] echo one one [07:28:46] sleep 2 [07:28:48] echo two two ``` By default, timestamps are formatted as `HH:MM:SS`. The format can be changed with `--timestamp-format`: ``` $ just --timestamp recipe --timestamp-format '%H:%M:%S%.3f %Z' [07:32:11:.349 UTC] echo one one [07:32:11:.350 UTC] sleep 2 [07:32:13:.352 UTC] echo two two ``` The argument to `--timestamp-format` is a `strftime`\-style format string, see the [`chrono` library docs](https://docs.rs/chrono/latest/chrono/format/strftime/index.html) for details. Signal Handling [Signals](https://en.wikipedia.org/wiki/Signal_\(IPC\)) are messages sent to running programs to trigger specific behavior. For example, `SIGINT` is sent to all processes in the terminal foreground process group when `CTRL-C` is pressed. `just` tries to exit when requested by a signal, but it also tries to avoid leaving behind running child processes, two goals which are somewhat in conflict. If `just` exits leaving behind child processes, the user will have no recourse but to `ps aux | grep` for the children and manually `kill` them, a tedious endeavor. Fatal Signals `SIGHUP`, `SIGINT`, and `SIGQUIT` are generated when the user closes the terminal, types `ctrl-c`, or types `ctrl-\`, respectively, and are sent to all processes in the foreground process group. `SIGTERM` is the default signal sent by the `kill` command, and is delivered only to its intended victim. When a child process is not running, `just` will exit immediately on receipt of any of the above signals. When a child process *is* running, `just` will wait until it terminates, to avoid leaving it behind. Additionally, on receipt of `SIGTERM`, `just` will forward `SIGTERM` to any running children1\.41.0, since unlike other fatal signals, `SIGTERM`, was likely sent to `just` alone. Regardless of whether a child process terminates successfully after `just` receives a fatal signal, `just` halts execution. `SIGINFO` `SIGINFO` is sent to all processes in the foreground process group when the user types `ctrl-t` on [BSD](https://en.wikipedia.org/wiki/Berkeley_Software_Distribution)\-derived operating systems, including MacOS, but not Linux. `just` responds by printing a list of all child process IDs and commands1\.41.0. Windows On Windows, `just` behaves as if it had received `SIGINT` when the user types `ctrl-c`. Other signals are unsupported. Changelog A changelog for the latest release is available in [CHANGELOG.md](https://raw.githubusercontent.com/casey/just/master/CHANGELOG.md). Changelogs for previous releases are available on [the releases page](https://github.com/casey/just/releases). `just --changelog` can also be used to make a `just` binary print its changelog. Miscellanea Re-running recipes when files change [`watchexec`](https://github.com/mattgreen/watchexec) can re-run any command when files change. To re-run the recipe `foo` when any file changes: ``` watchexec just foo ``` See `watchexec --help` for more info, including how to specify which files should be watched for changes. Parallelism Dependencies may be run in parallel with the `[parallel]` attribute. In this `justfile`, `foo`, `bar`, and `baz` will execute in parallel when `main` is run: ``` [parallel] main: foo bar baz foo: sleep 1 bar: sleep 1 baz: sleep 1 ``` GNU `parallel` may be used to run recipe lines concurrently: ``` parallel: #!/usr/bin/env -S parallel --shebang --ungroup --jobs {{ num_cpus() }} echo task 1 start; sleep 3; echo task 1 done echo task 2 start; sleep 3; echo task 2 done echo task 3 start; sleep 3; echo task 3 done echo task 4 start; sleep 3; echo task 4 done ``` Shell Alias For lightning-fast command running, put `alias j=just` in your shell's configuration file. Shell Completion Scripts Shell completion scripts for Bash, Elvish, Fish, Nushell, PowerShell, and Zsh are available in [release archives](https://github.com/casey/just/releases). The `just` binary can also generate the same completion scripts at runtime using `just --completions SHELL`: ``` $ just --completions bash > just ``` Bash The recommended approach is to use the `bash-completions` package to lazy-load the completion script: ``` mkdir -p ~/.local/share/bash-completion/completions just --completions bash > ~/.local/share/bash-completion/completions/just ``` If `bash-completions` is not installed, you can source the completion script in your `.bashrc`: ``` source <(just --completions bash) ``` If you use an alias like `alias j=just`, you should also save the completion script with the name `j` when lazy-loading: ``` just --completions bash > ~/.local/share/bash-completion/completions/j ``` Or if not lazy-loading, add this line after sourcing the completion script in your `.bashrc`: ``` complete -F _clap_complete_just -o bashdefault -o default j ``` Elvish In your `rc.elv`: ``` set edit:completion:arg-completer[just] = { |@args| eval (just --completions elvish | slurp) set @result = (edit:completion:arg-completer[just] $@args) put $@result } ``` Fish Save the completion script to the completions directory to lazy-load it: ``` mkdir -p ~/.config/fish/completions just --completions fish > ~/.config/fish/completions/just.fish ``` Nushell First save the completion script: ``` just --completions nushell | save -f ($nu.default-config-dir | path join just.nu) ``` Then in `config.nu`: ``` source just.nu ``` PowerShell In your PowerShell `$PROFILE`: ``` just --completions powershell | Out-String | Invoke-Expression ``` Zsh First save the completion script: ``` mkdir -p ~/.zsh/completions just --completions zsh > ~/.zsh/completions/_just ``` Then in your `.zshrc`: ``` fpath=(~/.zsh/completions $fpath) autoload -U compinit compinit ``` Man Page `just` can print its own man page with `just --man`. Man pages are written in [`roff`](https://en.wikipedia.org/wiki/Roff_%28software%29), a venerable markup language and one of the first practical applications of Unix. If you have [`groff`](https://www.gnu.org/software/groff/) installed you can view the man page with `just --man | groff -mandoc -Tascii | less`. Grammar A non-normative grammar of `justfile`s can be found in [GRAMMAR.md](https://github.com/casey/just/blob/master/GRAMMAR.md). just.sh Before `just` was a fancy Rust program it was a tiny shell script that called `make`. You can find the old version in [contrib/just.sh](https://github.com/casey/just/blob/master/contrib/just.sh). Global and User `justfile`s If you want some recipes to be available everywhere, you have a few options. Global Justfile `just --global-justfile`, or `just -g` for short, searches the following paths, in-order, for a justfile: - `$XDG_CONFIG_HOME/just/justfile` - `$HOME/.config/just/justfile` - `$HOME/justfile` - `$HOME/.justfile` You can put recipes that are used across many projects in a global justfile to easily invoke them from any directory. User justfile tips You can also adopt some of the following workflows. These tips assume you've created a `justfile` at `~/.user.justfile`, but you can put this `justfile` at any convenient path on your system. Recipe Aliases If you want to call the recipes in `~/.user.justfile` by name, and don't mind creating an alias for every recipe, add the following to your shell's initialization script: ``` for recipe in `just --justfile ~/.user.justfile --summary`; do alias $recipe="just --justfile ~/.user.justfile --working-directory . $recipe" done ``` Now, if you have a recipe called `foo` in `~/.user.justfile`, you can just type `foo` at the command line to run it. It took me way too long to realize that you could create recipe aliases like this. Notwithstanding my tardiness, I am very pleased to bring you this major advance in `justfile` technology. Forwarding Alias If you'd rather not create aliases for every recipe, you can create a single alias: ``` alias .j='just --justfile ~/.user.justfile --working-directory .' ``` Now, if you have a recipe called `foo` in `~/.user.justfile`, you can just type `.j foo` at the command line to run it. I'm pretty sure that nobody actually uses this feature, but it's there. ĀÆ\\\_(惄)\_/ĀÆ Customization You can customize the above aliases with additional options. For example, if you'd prefer to have the recipes in your `justfile` run in your home directory, instead of the current directory: ``` alias .j='just --justfile ~/.user.justfile --working-directory ~' ``` Node.js `package.json` Script Compatibility The following export statement gives `just` recipes access to local Node module binaries, and makes `just` recipe commands behave more like `script` entries in Node.js `package.json` files: ``` export PATH := "./node_modules/.bin:" + env_var('PATH') ``` Paths on Windows On Windows, all functions that return paths, except `invocation_directory()` will return `\`\-separated paths. When not using PowerShell or `cmd.exe` these paths should be quoted to prevent the `\`s from being interpreted as character escapes: ``` ls: echo '{{absolute_path(".")}}' ``` `cygpath.exe` is an executable included in some distributions of Unix userlands for Windows, including [Cygwin](https://www.cygwin.com/) and [Git](https://git-scm.com/downloads) for Windows. `just` uses `cygpath.exe` in two places: For backwards compatibility, `invocation_directory()`, uses `cygpath.exe` to convert the invocation directory into a unix-style `/`\-separated path. Use `invocation_directory_native()` to get the native, Windows-style path. On unix, `invocation_directory()` and `invocation_directory_native()` both return the same unix-style path. `cygpath.exe` is used also used to convert Unix-style shebang lines into Windows paths. As an alternative, the `[script]` attribute can be used, which does not depend on `cygpath.exe`. If `cygpath.exe` is available, you can use it to convert between path styles: ``` foo_unix := '/hello/world' foo_windows := shell('cygpath --windows $1', foo_unix) bar_windows := 'C:\hello\world' bar_unix := shell('cygpath --unix $1', bar_windows) ``` Remote Justfiles If you wish to include a `mod` or `import` source file in many `justfiles` without needing to duplicate it, you can use an optional `mod` or `import`, along with a recipe to fetch the module source: ``` import? 'foo.just' fetch: curl https://raw.githubusercontent.com/casey/just/master/justfile > foo.just ``` Given the above `justfile`, after running `just fetch`, the recipes in `foo.just` will be available. Printing Complex Strings `echo` can be used to print strings, but because it processes escape sequences, like `\n`, and different implementations of `echo` recognize different escape sequences, using `printf` is often a better choice. `printf` takes a C-style format string and any number of arguments, which are interpolated into the format string. This can be combined with indented, triple quoted strings to emulate shell heredocs. Substitution complex strings into recipe bodies with `{ā€¦}` can also lead to trouble as it may be split by the shell into multiple arguments depending on the presence of whitespace and quotes. Exporting complex strings as environment variables and referring to them with `"$NAME"`, note the double quotes, can also help. Putting all this together, to print a string verbatim to standard output, with all its various escape sequences and quotes undisturbed: ``` export FOO := ''' a complicated string with some dis\tur\bi\ng escape sequences and "quotes" of 'different' kinds ''' bar: printf %s "$FOO" ``` Alternatives and Prior Art There is no shortage of command runners! Some more or less similar alternatives to `just` include: - [make](https://en.wikipedia.org/wiki/Make_\(software\)): The Unix build tool that inspired `just`. There are a few different modern day descendents of the original `make`, including [FreeBSD Make](https://www.freebsd.org/cgi/man.cgi?make\(1\)) and [GNU Make](https://www.gnu.org/software/make/). - [task](https://github.com/go-task/task): A YAML-based command runner written in Go. - [maid](https://github.com/egoist/maid): A Markdown-based command runner written in JavaScript. - [microsoft/just](https://github.com/microsoft/just): A JavaScript-based command runner written in JavaScript. - [cargo-make](https://github.com/sagiegurari/cargo-make): A command runner for Rust projects. - [mmake](https://github.com/tj/mmake): A wrapper around `make` with a number of improvements, including remote includes. - [robo](https://github.com/tj/robo): A YAML-based command runner written in Go. - [mask](https://github.com/jakedeichert/mask): A Markdown-based command runner written in Rust. - [makesure](https://github.com/xonixx/makesure): A simple and portable command runner written in AWK and shell. - [haku](https://github.com/VladimirMarkelov/haku): A make-like command runner written in Rust. - [mise](https://mise.jdx.dev/): A development environment tool manager written in Rust supporting tasks in TOML files and standalone scripts. Contributing `just` welcomes your contributions! `just` is released under the maximally permissive [CC0](https://creativecommons.org/publicdomain/zero/1.0/legalcode.txt) public domain dedication and fallback license, so your changes must also be released under this license. Getting Started `just` is written in Rust. Use [rustup](https://www.rust-lang.org/tools/install) to install a Rust toolchain. `just` is extensively tested. All new features must be covered by unit or integration tests. Unit tests are under [src](https://github.com/casey/just/blob/master/src), live alongside the code being tested, and test code in isolation. Integration tests are in the [tests directory](https://github.com/casey/just/blob/master/tests) and test the `just` binary from the outside by invoking `just` on a given `justfile` and set of command-line arguments, and checking the output. You should write whichever type of tests are easiest to write for your feature while still providing good test coverage. Unit tests are useful for testing new Rust functions that are used internally and as an aid for development. A good example are the unit tests which cover the [`unindent()` function](https://github.com/casey/just/blob/master/src/unindent.rs), used to unindent triple-quoted strings and backticks. `unindent()` has a bunch of tricky edge cases which are easy to exercise with unit tests that call `unindent()` directly. Integration tests are useful for making sure that the final behavior of the `just` binary is correct. `unindent()` is also covered by integration tests which make sure that evaluating a triple-quoted string produces the correct unindented value. However, there are not integration tests for all possible cases. These are covered by faster, more concise unit tests that call `unindent()` directly. Integration tests use the `Test` struct, a builder which allows for easily invoking `just` with a given `justfile`, arguments, and environment variables, and checking the program's stdout, stderr, and exit code . Contribution Workflow 1. Make sure the feature is wanted. There should be an open issue about the feature with a comment from [@casey](https://github.com/casey) saying that it's a good idea or seems reasonable. If there isn't, open a new issue and ask for feedback. There are lots of good features which can't be merged, either because they aren't backwards compatible, have an implementation which would overcomplicate the codebase, or go against `just`'s design philosophy. 2. Settle on the design of the feature. If the feature has multiple possible implementations or syntaxes, make sure to nail down the details in the issue. 3. Clone `just` and start hacking. The best workflow is to have the code you're working on in an editor alongside a job that re-runs tests whenever a file changes. You can run such a job by installing [cargo-watch](https://github.com/watchexec/cargo-watch) with `cargo install cargo-watch` and running `just watch test`. 4. Add a failing test for your feature. Most of the time this will be an integration test which exercises the feature end-to-end. Look for an appropriate file to put the test in [tests](https://github.com/casey/just/blob/master/tests), or add a new file in [tests](https://github.com/casey/just/blob/master/tests) and add a `mod` statement importing that file in [tests/lib.rs](https://github.com/casey/just/blob/master/tests/lib.rs). 5. Implement the feature. 6. Run `just ci` to make sure that all tests, lints, and checks pass. Requires [mdBook](https://github.com/rust-lang/mdBook) and [mdbook-linkcheck](https://github.com/Michael-F-Bryan/mdbook-linkcheck). 7. Open a PR with the new code that is editable by maintainers. PRs often require rebasing and minor tweaks. If the PR is not editable by maintainers, each rebase and tweak will require a round trip of code review. Your PR may be summarily closed if it is not editable by maintainers. 8. Incorporate feedback. 9. Enjoy the sweet feeling of your PR getting merged\! Feel free to open a draft PR at any time for discussion and feedback. Hints Here are some hints to get you started with specific kinds of new features, which you can use in addition to the contribution workflow above. Adding a New Attribute 1. Write a new integration test in [tests/attributes.rs](https://github.com/casey/just/blob/master/tests/attributes.rs). 2. Add a new variant to the [`Attribute`](https://github.com/casey/just/blob/master/src/attribute.rs) enum. 3. Implement the functionality of the new attribute. 4. Run `just ci` to make sure that all tests pass. Janus [Janus](https://github.com/casey/janus) is a tool for checking whether a change to `just` breaks or changes the interpretation of existing `justfile`s. It collects and analyzes public `justfile`s on GitHub. Before merging a particularly large or gruesome change, Janus should be run to make sure that nothing breaks. Don't worry about running Janus yourself, Casey will happily run it for you on changes that need it. Minimum Supported Rust Version The minimum supported Rust version, or MSRV, is current stable Rust. It may build on older versions of Rust, but this is not guaranteed. New Releases New releases of `just` are made frequently so that users quickly get access to new features. Release commit messages use the following template: ``` Release x.y.z - Bump version: x.y.z ā†’ x.y.z - Update changelog - Update changelog contributor credits - Update dependencies - Update version references in readme ``` Frequently Asked Questions What are the idiosyncrasies of Make that Just avoids? `make` has some behaviors which are confusing, complicated, or make it unsuitable for use as a general command runner. One example is that under some circumstances, `make` won't actually run the commands in a recipe. For example, if you have a file called `test` and the following makefile: ``` test: ./test ``` `make` will refuse to run your tests: ``` $ make test make: `test' is up to date. ``` `make` assumes that the `test` recipe produces a file called `test`. Since this file exists and the recipe has no other dependencies, `make` thinks that it doesn't have anything to do and exits. To be fair, this behavior is desirable when using `make` as a build system, but not when using it as a command runner. You can disable this behavior for specific targets using `make`'s built-in [`.PHONY` target name](https://www.gnu.org/software/make/manual/html_node/Phony-Targets.html), but the syntax is verbose and can be hard to remember. The explicit list of phony targets, written separately from the recipe definitions, also introduces the risk of accidentally defining a new non-phony target. In `just`, all recipes are treated as if they were phony. Other examples of `make`'s idiosyncrasies include the difference between `=` and `:=` in assignments, the confusing error messages that are produced if you mess up your makefile, needing `$$` to use environment variables in recipes, and incompatibilities between different flavors of `make`. What's the relationship between Just and Cargo build scripts? [`cargo` build scripts](http://doc.crates.io/build-script.html) have a pretty specific use, which is to control how `cargo` builds your Rust project. This might include adding flags to `rustc` invocations, building an external dependency, or running some kind of codegen step. `just`, on the other hand, is for all the other miscellaneous commands you might run as part of development. Things like running tests in different configurations, linting your code, pushing build artifacts to a server, removing temporary files, and the like. Also, although `just` is written in Rust, it can be used regardless of the language or build system your project uses. Further Ramblings I personally find it very useful to write a `justfile` for almost every project, big or small. On a big project with multiple contributors, it's very useful to have a file with all the commands needed to work on the project close at hand. There are probably different commands to test, build, lint, deploy, and the like, and having them all in one place is useful and cuts down on the time you have to spend telling people which commands to run and how to type them. And, with an easy place to put commands, it's likely that you'll come up with other useful things which are part of the project's collective wisdom, but which aren't written down anywhere, like the arcane commands needed for some part of your revision control workflow, to install all your project's dependencies, or all the random flags you might need to pass to the build system. Some ideas for recipes: - Deploying/publishing the project - Building in release mode vs debug mode - Running in debug mode or with logging enabled - Complex git workflows - Updating dependencies - Running different sets of tests, for example fast tests vs slow tests, or running them with verbose output - Any complex set of commands that you really should write down somewhere, if only to be able to remember them Even for small, personal projects it's nice to be able to remember commands by name instead of ^Reverse searching your shell history, and it's a huge boon to be able to go into an old project written in a random language with a mysterious build system and know that all the commands you need to do whatever you need to do are in the `justfile`, and that if you type `just` something useful (or at least interesting!) will probably happen. For ideas for recipes, check out [this project's `justfile`](https://github.com/casey/just/blob/master/justfile), or some of the `justfile`s [out in the wild](https://github.com/search?q=path%3A**%2Fjustfile&type=code). Anyways, I think that's about it for this incredibly long-winded README. I hope you enjoy using `just` and find great success and satisfaction in all your computational endeavors\! šŸ˜ø [šŸ”¼ Back to the top\!](https://github.com/casey/just#just)
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