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Raw Queries and Responses

1. Shard Calculation

Query:

Response:

Calculated Shard: 1 (from laksa008)

2. Crawled Status Check

Query:

curl -X POST \
  'http://laksa001.int.ahrefs:8124/' \
  -H 'Content-Type: text/plain' \
  -H 'X-ClickHouse-Database: crawler3' \
  -H 'Authorization: Basic YXBpOg==' \
  -d 'SELECT getAhrefsURLFromUnparsed(src_unparsed) AS found_url, ifNull(toUnixTimestamp(download_stamp), 0) AS crawl_time, ifNull(toUnixTimestamp(props_url_first_seen), 0) AS first_indexed_time, download_http_code AS http_code, src_unparsed AS src_unparsed, src_root_hash AS src_root_hash, history_drop_reason AS history_drop_reason, meta_title AS meta_title, meta_descriptions AS meta_descriptions, attrs_boilerpipe_text AS attrs_boilerpipe_text, attrs_markdown AS attrs_markdown, attrs_readable_markdown AS attrs_readable_markdown, meta_canonical AS meta_canonical FROM crawler3.page_info_local FINAL PREWHERE (src_root_hash, src_unparsed) IN ((getAhrefsRootHashFromUnparsed(getAhrefsUnparsedNoserviceFromURL(\'https://www.softwaretestinghelp.com/unix-shell-loops/\')), getAhrefsUnparsedNoserviceFromURL(\'https://www.softwaretestinghelp.com/unix-shell-loops/\'))) FORMAT JSONEachRow'

Response:

{"found_url":"https:\/\/www.softwaretestinghelp.com\/unix-shell-loops\/","crawl_time":1775185588,"first_indexed_time":1526454394,"http_code":200,"src_unparsed":"com,softwaretestinghelp!www,\/unix-shell-loops\/ s443","src_root_hash":"15064000948048152601","history_drop_reason":null,"meta_title":"Unix Shell Loop Types: Do While Loop, For Loop, Until Loop in Unix","meta_descriptions":["Overview of Unix Shell Loops and different Loop Types like Unix Do While Loop, Unix For Loop, Unix Until Loop. Learn these Unix loops with examples."],"attrs_boilerpipe_text":"By\nVijay\nBy Vijay\nI'm Vijay, and I've been working on this blog for the past 20+ years! I’ve been in the IT industry for more than 20 years now. I completed my graduation in B.E. Computer Science from a reputed Pune university and then started my career in…\nUpdated April 1, 2025\nOverview of Unix Shell Loops and Different Loop Types like:\nUnix Do While Loop\nUnix For Loop\nUnix Until Loop\nIn this tutorial, we will cover the control instructions that are used to iterate a set of commands over a series of data. \nUnix offers three loop structures of which we can repeat a part of a program at a specified number of times.\nUnix Video #17:\nLoops in Unix\nYou may use different loops based on the situation.\nThey are:\n#1) Unix For loop statement\nExample:\nThis program will add 1+2+3+4+5 and the result will be 15\nfor i in 1 2 3 4 5\n do\n sum=`expr $sum + $i`\n done\n echo $sum\n#2) Unix While loop statement\nExample:\nThis program will print the value of ‘a’ five times, from 1 to 5.\na=1\n while [ $a -le 5 ]\n do\n echo “value of a=” $a\n a=`expr $a + 1`\n done\n#3) Unix Until loop statement\nThis program will print the value of ‘a’ two times from 1 to 2.\na=1\n until [ $a -ge 3 ]\n do\n echo “value of a=” $a\n a=`expr $a + 1`\n done\nWhile running these loops, there may be a need to break out of the loop in some condition before completing all the iterations or to restart the loop before completing the remaining statements. This can be achieved with the ‘break’ and ‘continue’ statements.\nThe following program illustrates the ‘break’ operation:\nnum=1\n while [ $num -le 5 ]\n do\n read var\n if [ $var -lt 0 ]\n then\n break\n fi\n num=`expr $num + 1`\n done\n echo “The loop breaks for negative numbers”\nOur upcoming tutorial will brief you more about working with Functions in Unix.\nPREV Tutorial\n|\nNEXT Tutorial\nWas this helpful?\nThanks for your feedback!\nREAD MORE FROM THIS SERIES:\nHow to Install Software in Linux (3 Proper Ways)\nUNIX Tutorial for Beginners (20+ In-depth Unix Training Videos)\nUnix Commands: Basic and Advanced Unix Commands with Examples\nUnix File System Commands Touch, Cat, Cp, Mv, Rm, Mkdir (Part B)\nUnix Processes Control Commands Like Ps and Top (Part C)\nUnix Utilities Programs Commands: Which, Man, Find Su, Sudo (Part D)\nFile Manipulation in Unix: Overview of Unix File System\nUnix File Access Permissions: Unix Chmod, Chown and Chgrp\nHow to Compare Two Files in Unix: File Comparison Commands\nUnix Special Characters or Metacharacters for File Manipulation\nHow to Use Unix Regular Expressions\nUnix Shell Scripting Tutorial with Examples\nWorking with Vi Editor in Unix\nWorking with Unix Variables: Features of Shell Scripting\nUnix Shell Script Arithmetic and Boolean Operators Examples\nUnix Conditional Statements: If Then Else and Relational Operators\nUsing Switch Case in Unix Shell Scripting: Case-esac Statement\nUnix Shell Loop Types: Do While Loop, For Loop, Until Loop in Unix\nUnix Shell Script Functions with Parameters and Return\nUnix Text Processing Commands: Unix Filters with Examples\nUnix Pipes Tutorial: Pipes in Unix Programming\nMore Unix Filter and Awk, Sed Commands in Text Processing\nCommand Line Arguments in Unix Shell Script with Example\nProcesses in Unix: Process Control and Debugging Commands\nAdvanced Unix Shell Scripting: Arrays, File and String Test Operators, Special V…\nWhat is Unix: A Brief Introduction to Unix\nUnix Vs Linux: What is Difference Between UNIX and Linux\nUnix Permissions: File Permissions in Unix with Examples\nGrep Command in Unix with Simple Examples\nCut Command in Unix with Examples\nTar Command in Unix To Create Backups (Examples)\nFind Command in Unix: Find Files with Unix Find File (Examples)\nLs Command in Unix with Examples\nUnix Cat Command Syntax, Options with Examples\nUnix Sort Command with Syntax, Options and Examples\nLinux vs Windows Difference: Which Is The Best Operating System?\nLinux Commands Tutorial: Learn Basic Linux Commands For Beginners\n12 SCP Command Examples To Securely Transfer Files In Linux\nUbuntu Vs Windows 10 – Which Is A Better OS","attrs_markdown":"[Skip to content](https:\/\/www.softwaretestinghelp.com\/unix-shell-loops\/#content \"Skip to content\")\n\n[Software Testing Help](https:\/\/www.softwaretestinghelp.com\/)\n\nMenu\n\nMENUMENU\n\n- [Home](https:\/\/www.softwaretestinghelp.com\/ \"Software Testing Home\")\n- [Resources](https:\/\/www.softwaretestinghelp.com\/resources\/ \"Testing RESOURCES\")\n- [FREE eBooks](https:\/\/www.softwaretestinghelp.com\/practical-software-testing-new-free-ebook-download\/ \"FREE eBooks\")\n- [QA Testing](https:\/\/www.softwaretestinghelp.com\/manual-testing-tutorial-1\/)\n  - 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- [MongoDB](https:\/\/www.softwaretestinghelp.com\/mongodb\/)\n    - - [Data Generation Tools](https:\/\/www.softwaretestinghelp.com\/test-data-generation-tools\/)\n  - - - [Data Integration Tools](https:\/\/www.softwaretestinghelp.com\/tools\/26-best-data-integration-tools\/)\n    - - [Data Masking Tools](https:\/\/www.softwaretestinghelp.com\/data-masking-tools\/)\n    - - [Data Migration Tools](https:\/\/www.softwaretestinghelp.com\/data-migration-tools\/)\n    - - [ETL Tools](https:\/\/www.softwaretestinghelp.com\/best-etl-tools\/)\n- [More Tutorials](https:\/\/www.softwaretestinghelp.com\/top-tutorials-and-tools\/)\n\n# Unix Shell Loop Types: Do While Loop, For Loop, Until Loop in Unix\nBy\n\n[Vijay](https:\/\/www.softwaretestinghelp.com\/author\/vijay\/)\n\nBy Vijay\n\n![](data:image\/svg+xml,%3Csvg%20xmlns='http:\/\/www.w3.org\/2000\/svg'%20viewBox='0%200%20150%20150'%3E%3C\/svg%3E)\n\n![](https:\/\/www.softwaretestinghelp.com\/wp-content\/qa\/uploads\/2018\/12\/Vijay-STH-blog-150x150.jpg)\n\nI'm Vijay, and I've been working on this blog for the past 20+ years! I’ve been in the IT industry for more than 20 years now. I completed my graduation in B.E. Computer Science from a reputed Pune university and then started my career in…\n\n[Full Bio \\>](https:\/\/www.softwaretestinghelp.com\/author\/vijay\/)\n\nFollow\n\n[![](data:image\/svg+xml,%3Csvg%20xmlns='http:\/\/www.w3.org\/2000\/svg'%20viewBox='0%200%20512%20512'%3E%3C\/svg%3E)![](https:\/\/www.softwaretestinghelp.com\/wp-content\/themes\/generatepress-child\/img\/facebook.png)](https:\/\/www.facebook.com\/SoftwareTestingHelp\/)\n\n[![](data:image\/svg+xml,%3Csvg%20xmlns='http:\/\/www.w3.org\/2000\/svg'%20viewBox='0%200%20512%20512'%3E%3C\/svg%3E)![](https:\/\/www.softwaretestinghelp.com\/wp-content\/themes\/generatepress-child\/img\/linkedin.png)](https:\/\/www.linkedin.com\/in\/shindevijaykr\/)\n\n[![](data:image\/svg+xml,%3Csvg%20xmlns='http:\/\/www.w3.org\/2000\/svg'%20viewBox='0%200%20512%20512'%3E%3C\/svg%3E)![](https:\/\/www.softwaretestinghelp.com\/wp-content\/themes\/generatepress-child\/img\/twitter.png)](https:\/\/twitter.com\/vijayshinde)\n***\nLearn about our [editorial policies](https:\/\/www.softwaretestinghelp.com\/editorial-policy-review-process\/).\n\nUpdated April 1, 2025\n\n**Overview of Unix Shell Loops and Different Loop Types like:**\n\n- Unix Do While Loop\n- Unix For Loop\n- Unix Until Loop\n\nIn this tutorial, we will cover the control instructions that are used to iterate a set of commands over a series of data.\n\n[![Unix Shell Loops](https:\/\/www.softwaretestinghelp.com\/wp-content\/qa\/uploads\/2019\/10\/Unix-Shell-Loops.png)](https:\/\/www.softwaretestinghelp.com\/wp-content\/qa\/uploads\/2019\/10\/Unix-Shell-Loops.png)\n\nUnix offers three loop structures of which we can repeat a part of a program at a specified number of times.\n\n**Unix Video \\#17:**\n\n### Loops in Unix\n**You may use different loops based on the situation.**\n\n**They are:**\n\n**\\#1) Unix For loop statement**\n\n**Example:** This program will add 1+2+3+4+5 and the result will be 15\n```\nfor i in 1 2 3 4 5\n do\n sum=`expr $sum + $i`\n done\n echo $sum\n```\n**\\#2) Unix While loop statement**\n\n**Example:** This program will print the value of ‘a’ five times, from 1 to 5.\n```\na=1\n while [ $a -le 5 ]\n do\n echo “value of a=” $a\n a=`expr $a + 1`\n done\n```\n**\\#3) Unix Until loop statement**\n\nThis program will print the value of ‘a’ two times from 1 to 2.\n```\na=1\n until [ $a -ge 3 ]\n do\n echo “value of a=” $a\n a=`expr $a + 1`\n done\n```\nWhile running these loops, there may be a need to break out of the loop in some condition before completing all the iterations or to restart the loop before completing the remaining statements. This can be achieved with the ‘break’ and ‘continue’ statements.\n\n**The following program illustrates the ‘break’ operation:**\n```\n num=1\n while [ $num -le 5 ]\n do\n read var\n if [ $var -lt 0 ]\n then\n break\n fi\n num=`expr $num + 1`\n done\n echo “The loop breaks for negative numbers”\n```\n***Our upcoming tutorial will brief you more about working with Functions in Unix.***\n\n**[PREV Tutorial](https:\/\/www.softwaretestinghelp.com\/unix-switch-case\/) \\| [NEXT Tutorial](https:\/\/www.softwaretestinghelp.com\/unix-functions\/)**\n\n### Was this helpful?\nSubmit\n\nCancel\n\nThanks for your feedback\\!\n\n### Recommended Reading\n- [Unix Pipes Tutorial: Pipes in Unix Programming](https:\/\/www.softwaretestinghelp.com\/unix-pipes\/)\n  [![Pipes in Unix Programming](data:image\/svg+xml,%3Csvg%20xmlns='http:\/\/www.w3.org\/2000\/svg'%20viewBox='0%200%20240%20135'%3E%3C\/svg%3E)![Pipes in Unix Programming](https:\/\/www.softwaretestinghelp.com\/wp-content\/qa\/uploads\/2019\/10\/Pipes-in-Unix-Programming-1.png)](https:\/\/www.softwaretestinghelp.com\/unix-pipes\/)\n  Overview of Pipes in Unix Programming: In this tutorial, we will learn more about Unix Pipes. Later, we will work with some of the remaining filter commands and see an example of piping them together. Unix Video \\#20: Pipes in Unix A series of filter commands can be piped together…\n- [Java For Loop Tutorial With Program Examples](https:\/\/www.softwaretestinghelp.com\/java-for-loop-tutorial\/)\n  [![Java for-loop](data:image\/svg+xml,%3Csvg%20xmlns='http:\/\/www.w3.org\/2000\/svg'%20viewBox='0%200%20240%20135'%3E%3C\/svg%3E)![Java for-loop](https:\/\/www.softwaretestinghelp.com\/wp-content\/qa\/uploads\/2020\/10\/Java-for-loop-1.png)](https:\/\/www.softwaretestinghelp.com\/java-for-loop-tutorial\/)\n  This tutorial will explain the concept of Java For Loop along with its syntax, description, flowchart, and programming examples: In this tutorial, we will discuss the “for-loop” in Java. We will explore each and every aspect of the looping concept along with the way of using it. This tutorial will…\n- [Unix Text Processing Commands: Unix Filters with Examples](https:\/\/www.softwaretestinghelp.com\/unix-text-processing-commands\/)\n  [![Unix Text Processing Commands](data:image\/svg+xml,%3Csvg%20xmlns='http:\/\/www.w3.org\/2000\/svg'%20viewBox='0%200%20240%20135'%3E%3C\/svg%3E)![Unix Text Processing Commands](https:\/\/www.softwaretestinghelp.com\/wp-content\/qa\/uploads\/2019\/10\/Unix-Text-Processing-Commands.png)](https:\/\/www.softwaretestinghelp.com\/unix-text-processing-commands\/)\n  Overview of Unix Filters Text Processing Utilities: In this tutorial, we will learn about filters and work with various filter commands. Filters are commands that read input from stdin and write output to stdout. By default, when using a shell terminal, the stdin is from the keyboard, and the stdout is…\n- [What is Unix: A Brief Introduction to Unix](https:\/\/www.softwaretestinghelp.com\/unix-introduction\/)\n  [![\\_Introduction to Unix (1)](data:image\/svg+xml,%3Csvg%20xmlns='http:\/\/www.w3.org\/2000\/svg'%20viewBox='0%200%20240%20135'%3E%3C\/svg%3E)![\\_Introduction to Unix (1)](https:\/\/www.softwaretestinghelp.com\/wp-content\/qa\/uploads\/2022\/05\/Introduction-to-Unix-1.png)](https:\/\/www.softwaretestinghelp.com\/unix-introduction\/)\n  Introduction to Unix Operating System: Let's start with Tutorial \\#1: 'What is Unix' in this series. In this tutorial, you will be able to understand the basic concepts of operating systems, the features of Unix, along its Architecture. =\\> Click here for the Complete Unix Tutorial series Unix Video \\#1:…\n***\n**READ MORE FROM THIS SERIES:**\n\n- [How to Install Software in Linux (3 Proper Ways)](https:\/\/www.softwaretestinghelp.com\/3-major-ways-how-to-install-new-software-on-linux\/)\n- [UNIX Tutorial for Beginners (20+ In-depth Unix Training Videos)](https:\/\/www.softwaretestinghelp.com\/unix-tutorials\/)\n- [Unix Commands: Basic and Advanced Unix Commands with Examples](https:\/\/www.softwaretestinghelp.com\/unix-commands\/)\n- [Unix File System Commands Touch, Cat, Cp, Mv, Rm, Mkdir (Part B)](https:\/\/www.softwaretestinghelp.com\/unix-file-system-commands\/)\n- [Unix Processes Control Commands Like Ps and Top (Part C)](https:\/\/www.softwaretestinghelp.com\/unix-processes-control-command\/)\n- [Unix Utilities Programs Commands: Which, Man, Find Su, Sudo (Part D)](https:\/\/www.softwaretestinghelp.com\/unix-utilities-programs-commands\/)\n- [File Manipulation in Unix: Overview of Unix File System](https:\/\/www.softwaretestinghelp.com\/file-manipulation-unix\/)\n- [Unix File Access Permissions: Unix Chmod, Chown and Chgrp](https:\/\/www.softwaretestinghelp.com\/unix-file-access-permissions\/)\n- [How to Compare Two Files in Unix: File Comparison Commands](https:\/\/www.softwaretestinghelp.com\/compare-two-files-unix\/)\n- [Unix Special Characters or Metacharacters for File Manipulation](https:\/\/www.softwaretestinghelp.com\/unix-metacharacters\/)\n- [How to Use Unix Regular Expressions](https:\/\/www.softwaretestinghelp.com\/unix-regular-expressions\/)\n- [Unix Shell Scripting Tutorial with Examples](https:\/\/www.softwaretestinghelp.com\/unix-shell-scripting-tutorial\/)\n- [Working with Vi Editor in Unix](https:\/\/www.softwaretestinghelp.com\/unix-vi-editor\/)\n- [Working with Unix Variables: Features of Shell Scripting](https:\/\/www.softwaretestinghelp.com\/unix-variables\/)\n- [Unix Shell Script Arithmetic and Boolean Operators Examples](https:\/\/www.softwaretestinghelp.com\/unix-arithmetic-boolean-operators\/)\n- [Unix Conditional Statements: If Then Else and Relational Operators](https:\/\/www.softwaretestinghelp.com\/unix-conditional-statements\/)\n- [Using Switch Case in Unix Shell Scripting: Case-esac Statement](https:\/\/www.softwaretestinghelp.com\/unix-switch-case\/)\n- [Unix Shell Loop Types: Do While Loop, For Loop, Until Loop in Unix](https:\/\/www.softwaretestinghelp.com\/unix-shell-loops\/)\n- [Unix Shell Script Functions with Parameters and Return](https:\/\/www.softwaretestinghelp.com\/unix-functions\/)\n- [Unix Text Processing Commands: Unix Filters with Examples](https:\/\/www.softwaretestinghelp.com\/unix-text-processing-commands\/)\n- [Unix Pipes Tutorial: Pipes in Unix Programming](https:\/\/www.softwaretestinghelp.com\/unix-pipes\/)\n- [More Unix Filter and Awk, Sed Commands in Text Processing](https:\/\/www.softwaretestinghelp.com\/unix-filter-awk-sed-commands\/)\n- [Command Line Arguments in Unix Shell Script with Example](https:\/\/www.softwaretestinghelp.com\/unix-command-line-arguments\/)\n- [Processes in Unix: Process Control and Debugging Commands](https:\/\/www.softwaretestinghelp.com\/unix-processes\/)\n- [Advanced Unix Shell Scripting: Arrays, File and String Test Operators, Special V…](https:\/\/www.softwaretestinghelp.com\/advanced-shell-scripting\/)\n- [What is Unix: A Brief Introduction to Unix](https:\/\/www.softwaretestinghelp.com\/unix-introduction\/)\n- [Unix Vs Linux: What is Difference Between UNIX and Linux](https:\/\/www.softwaretestinghelp.com\/unix-vs-linux\/)\n- [Unix Permissions: File Permissions in Unix with Examples](https:\/\/www.softwaretestinghelp.com\/unix-permissions\/)\n- [Grep Command in Unix with Simple Examples](https:\/\/www.softwaretestinghelp.com\/grep-command-in-unix\/)\n- [Cut Command in Unix with 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without permission. SoftwareTestingHelp® is a registered trademark.   \n©SoftwareTestingHelp 2025 — Read our  **[Copyright Policy](https:\/\/www.softwaretestinghelp.com\/copyright-policy\/) \\| [Privacy Policy](https:\/\/www.softwaretestinghelp.com\/privacy\/) \\| [Terms](https:\/\/www.softwaretestinghelp.com\/terms-of-use\/) \\| [Cookie Policy](https:\/\/www.softwaretestinghelp.com\/cookie-policy\/) \\| [Affiliate Disclaimer](https:\/\/www.softwaretestinghelp.com\/affiliate-disclaimer\/)**\n\n[![Software Testing Help](data:image\/svg+xml,%3Csvg%20xmlns='http:\/\/www.w3.org\/2000\/svg'%20viewBox='0%200%20524%2039'%3E%3C\/svg%3E)![Software Testing Help](https:\/\/www.softwaretestinghelp.com\/wp-content\/qa\/uploads\/2023\/03\/Thanks-for-reading-STH.png)](https:\/\/www.softwaretestinghelp.com\/become-an-author\/)","attrs_readable_markdown":"By [Vijay](https:\/\/www.softwaretestinghelp.com\/author\/vijay\/) By Vijay ![](https:\/\/www.softwaretestinghelp.com\/wp-content\/qa\/uploads\/2018\/12\/Vijay-STH-blog-150x150.jpg) I'm Vijay, and I've been working on this blog for the past 20+ years! I’ve been in the IT industry for more than 20 years now. I completed my graduation in B.E. Computer Science from a reputed Pune university and then started my career in… Updated April 1, 2025\n\n**Overview of Unix Shell Loops and Different Loop Types like:**\n\n- Unix Do While Loop\n- Unix For Loop\n- Unix Until Loop\n\nIn this tutorial, we will cover the control instructions that are used to iterate a set of commands over a series of data.\n\n[![Unix Shell Loops](https:\/\/www.softwaretestinghelp.com\/wp-content\/qa\/uploads\/2019\/10\/Unix-Shell-Loops.png)](https:\/\/www.softwaretestinghelp.com\/wp-content\/qa\/uploads\/2019\/10\/Unix-Shell-Loops.png)\n\nUnix offers three loop structures of which we can repeat a part of a program at a specified number of times.\n\n**Unix Video \\#17:**\n\n### Loops in Unix\n**You may use different loops based on the situation.**\n\n**They are:**\n\n**\\#1) Unix For loop statement**\n\n**Example:** This program will add 1+2+3+4+5 and the result will be 15\n```\nfor i in 1 2 3 4 5\n do\n sum=`expr $sum + $i`\n done\n echo $sum\n```\n**\\#2) Unix While loop statement**\n\n**Example:** This program will print the value of ‘a’ five times, from 1 to 5.\n```\na=1\n while [ $a -le 5 ]\n do\n echo “value of a=” $a\n a=`expr $a + 1`\n done\n```\n**\\#3) Unix Until loop statement**\n\nThis program will print the value of ‘a’ two times from 1 to 2.\n```\na=1\n until [ $a -ge 3 ]\n do\n echo “value of a=” $a\n a=`expr $a + 1`\n done\n```\nWhile running these loops, there may be a need to break out of the loop in some condition before completing all the iterations or to restart the loop before completing the remaining statements. This can be achieved with the ‘break’ and ‘continue’ statements.\n\n**The following program illustrates the ‘break’ operation:**\n```\n num=1\n while [ $num -le 5 ]\n do\n read var\n if [ $var -lt 0 ]\n then\n break\n fi\n num=`expr $num + 1`\n done\n echo “The loop breaks for negative numbers”\n```\n***Our upcoming tutorial will brief you more about working with Functions in Unix.***\n\n**[PREV Tutorial](https:\/\/www.softwaretestinghelp.com\/unix-switch-case\/) \\| [NEXT Tutorial](https:\/\/www.softwaretestinghelp.com\/unix-functions\/)**\n\nWas this helpful?\n\nThanks for your feedback\\!\n***\n**READ MORE FROM THIS SERIES:**\n\n- [How to Install Software in Linux (3 Proper Ways)](https:\/\/www.softwaretestinghelp.com\/3-major-ways-how-to-install-new-software-on-linux\/)\n- [UNIX Tutorial for Beginners (20+ In-depth Unix Training Videos)](https:\/\/www.softwaretestinghelp.com\/unix-tutorials\/)\n- [Unix Commands: Basic and Advanced Unix Commands with Examples](https:\/\/www.softwaretestinghelp.com\/unix-commands\/)\n- [Unix File System Commands Touch, Cat, Cp, Mv, Rm, Mkdir (Part B)](https:\/\/www.softwaretestinghelp.com\/unix-file-system-commands\/)\n- [Unix Processes Control Commands Like Ps and Top (Part C)](https:\/\/www.softwaretestinghelp.com\/unix-processes-control-command\/)\n- [Unix Utilities Programs Commands: Which, Man, Find Su, Sudo (Part D)](https:\/\/www.softwaretestinghelp.com\/unix-utilities-programs-commands\/)\n- [File Manipulation in Unix: Overview of Unix File System](https:\/\/www.softwaretestinghelp.com\/file-manipulation-unix\/)\n- [Unix File Access Permissions: Unix Chmod, Chown and Chgrp](https:\/\/www.softwaretestinghelp.com\/unix-file-access-permissions\/)\n- [How to Compare Two Files in Unix: File Comparison Commands](https:\/\/www.softwaretestinghelp.com\/compare-two-files-unix\/)\n- [Unix Special Characters or Metacharacters for File Manipulation](https:\/\/www.softwaretestinghelp.com\/unix-metacharacters\/)\n- [How to Use Unix Regular Expressions](https:\/\/www.softwaretestinghelp.com\/unix-regular-expressions\/)\n- [Unix Shell Scripting Tutorial with Examples](https:\/\/www.softwaretestinghelp.com\/unix-shell-scripting-tutorial\/)\n- [Working with Vi Editor in Unix](https:\/\/www.softwaretestinghelp.com\/unix-vi-editor\/)\n- [Working with Unix Variables: Features of Shell Scripting](https:\/\/www.softwaretestinghelp.com\/unix-variables\/)\n- [Unix Shell Script Arithmetic and Boolean Operators Examples](https:\/\/www.softwaretestinghelp.com\/unix-arithmetic-boolean-operators\/)\n- [Unix Conditional Statements: If Then Else and Relational Operators](https:\/\/www.softwaretestinghelp.com\/unix-conditional-statements\/)\n- [Using Switch Case in Unix Shell Scripting: Case-esac Statement](https:\/\/www.softwaretestinghelp.com\/unix-switch-case\/)\n- [Unix Shell Loop Types: Do While Loop, For Loop, Until Loop in Unix](https:\/\/www.softwaretestinghelp.com\/unix-shell-loops\/)\n- [Unix Shell Script Functions with Parameters and Return](https:\/\/www.softwaretestinghelp.com\/unix-functions\/)\n- [Unix Text Processing Commands: Unix Filters with Examples](https:\/\/www.softwaretestinghelp.com\/unix-text-processing-commands\/)\n- [Unix Pipes Tutorial: Pipes in Unix Programming](https:\/\/www.softwaretestinghelp.com\/unix-pipes\/)\n- [More Unix Filter and Awk, Sed Commands in Text Processing](https:\/\/www.softwaretestinghelp.com\/unix-filter-awk-sed-commands\/)\n- [Command Line Arguments in Unix Shell Script with Example](https:\/\/www.softwaretestinghelp.com\/unix-command-line-arguments\/)\n- [Processes in Unix: Process Control and Debugging Commands](https:\/\/www.softwaretestinghelp.com\/unix-processes\/)\n- [Advanced Unix Shell Scripting: Arrays, File and String Test Operators, Special V…](https:\/\/www.softwaretestinghelp.com\/advanced-shell-scripting\/)\n- [What is Unix: A Brief Introduction to Unix](https:\/\/www.softwaretestinghelp.com\/unix-introduction\/)\n- [Unix Vs Linux: What is Difference Between UNIX and Linux](https:\/\/www.softwaretestinghelp.com\/unix-vs-linux\/)\n- [Unix Permissions: File Permissions in Unix with Examples](https:\/\/www.softwaretestinghelp.com\/unix-permissions\/)\n- [Grep Command in Unix with Simple Examples](https:\/\/www.softwaretestinghelp.com\/grep-command-in-unix\/)\n- [Cut Command in Unix with Examples](https:\/\/www.softwaretestinghelp.com\/cut-command-in-unix\/)\n- [Tar Command in Unix To Create Backups (Examples)](https:\/\/www.softwaretestinghelp.com\/tar-command-in-unix\/)\n- [Find Command in Unix: Find Files with Unix Find File (Examples)](https:\/\/www.softwaretestinghelp.com\/find-command-in-unix\/)\n- [Ls Command in Unix with Examples](https:\/\/www.softwaretestinghelp.com\/ls-command-in-unix\/)\n- [Unix Cat Command Syntax, Options with Examples](https:\/\/www.softwaretestinghelp.com\/unix-cat-command\/)\n- [Unix Sort Command with Syntax, Options and Examples](https:\/\/www.softwaretestinghelp.com\/unix-sort-command\/)\n- [Linux vs Windows Difference: Which Is The Best Operating System?](https:\/\/www.softwaretestinghelp.com\/linux-vs-windows\/)\n- [Linux Commands Tutorial: Learn Basic Linux Commands For Beginners](https:\/\/www.softwaretestinghelp.com\/linux-commands-tutorial\/)\n- [12 SCP Command Examples To Securely Transfer Files In Linux](https:\/\/www.softwaretestinghelp.com\/scp-command-tutorial\/)\n- [Ubuntu Vs Windows 10 – Which Is A Better OS](https:\/\/www.softwaretestinghelp.com\/ubuntu-vs-windows\/)\n***","meta_canonical":null}

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INDEXABLE

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Filter	Status	Condition	Details
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Meta Title	Unix Shell Loop Types: Do While Loop, For Loop, Until Loop in Unix
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Boilerpipe Text	By Vijay By Vijay I'm Vijay, and I've been working on this blog for the past 20+ years! I’ve been in the IT industry for more than 20 years now. I completed my graduation in B.E. Computer Science from a reputed Pune university and then started my career in… Updated April 1, 2025 Overview of Unix Shell Loops and Different Loop Types like: Unix Do While Loop Unix For Loop Unix Until Loop In this tutorial, we will cover the control instructions that are used to iterate a set of commands over a series of data. Unix offers three loop structures of which we can repeat a part of a program at a specified number of times. Unix Video #17: Loops in Unix You may use different loops based on the situation. They are: #1) Unix For loop statement Example: This program will add 1+2+3+4+5 and the result will be 15 for i in 1 2 3 4 5 do sum=`expr $sum + $i` done echo $sum #2) Unix While loop statement Example: This program will print the value of ‘a’ five times, from 1 to 5. a=1 while [ $a -le 5 ] do echo “value of a=” $a a=`expr $a + 1` done #3) Unix Until loop statement This program will print the value of ‘a’ two times from 1 to 2. a=1 until [ $a -ge 3 ] do echo “value of a=” $a a=`expr $a + 1` done While running these loops, there may be a need to break out of the loop in some condition before completing all the iterations or to restart the loop before completing the remaining statements. This can be achieved with the ‘break’ and ‘continue’ statements. The following program illustrates the ‘break’ operation: num=1 while [ $num -le 5 ] do read var if [ $var -lt 0 ] then break fi num=`expr $num + 1` done echo “The loop breaks for negative numbers” Our upcoming tutorial will brief you more about working with Functions in Unix. PREV Tutorial \| NEXT Tutorial Was this helpful? Thanks for your feedback! READ MORE FROM THIS SERIES: How to Install Software in Linux (3 Proper Ways) UNIX Tutorial for Beginners (20+ In-depth Unix Training Videos) Unix Commands: Basic and Advanced Unix Commands with Examples Unix File System Commands Touch, Cat, Cp, Mv, Rm, Mkdir (Part B) Unix Processes Control Commands Like Ps and Top (Part C) Unix Utilities Programs Commands: Which, Man, Find Su, Sudo (Part D) File Manipulation in Unix: Overview of Unix File System Unix File Access Permissions: Unix Chmod, Chown and Chgrp How to Compare Two Files in Unix: File Comparison Commands Unix Special Characters or Metacharacters for File Manipulation How to Use Unix Regular Expressions Unix Shell Scripting Tutorial with Examples Working with Vi Editor in Unix Working with Unix Variables: Features of Shell Scripting Unix Shell Script Arithmetic and Boolean Operators Examples Unix Conditional Statements: If Then Else and Relational Operators Using Switch Case in Unix Shell Scripting: Case-esac Statement Unix Shell Loop Types: Do While Loop, For Loop, Until Loop in Unix Unix Shell Script Functions with Parameters and Return Unix Text Processing Commands: Unix Filters with Examples Unix Pipes Tutorial: Pipes in Unix Programming More Unix Filter and Awk, Sed Commands in Text Processing Command Line Arguments in Unix Shell Script with Example Processes in Unix: Process Control and Debugging Commands Advanced Unix Shell Scripting: Arrays, File and String Test Operators, Special V… What is Unix: A Brief Introduction to Unix Unix Vs Linux: What is Difference Between UNIX and Linux Unix Permissions: File Permissions in Unix with Examples Grep Command in Unix with Simple Examples Cut Command in Unix with Examples Tar Command in Unix To Create Backups (Examples) Find Command in Unix: Find Files with Unix Find File (Examples) Ls Command in Unix with Examples Unix Cat Command Syntax, Options with Examples Unix Sort Command with Syntax, Options and Examples Linux vs Windows Difference: Which Is The Best Operating System? Linux Commands Tutorial: Learn Basic Linux Commands For Beginners 12 SCP Command Examples To Securely Transfer Files In Linux Ubuntu Vs Windows 10 – Which Is A Better OS
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I’ve been in the IT industry for more than 20 years now. I completed my graduation in B.E. Computer Science from a reputed Pune university and then started my career in… [Full Bio \>](https://www.softwaretestinghelp.com/author/vijay/) Follow [![](data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%20512%20512'%3E%3C/svg%3E)![](https://www.softwaretestinghelp.com/wp-content/themes/generatepress-child/img/facebook.png)](https://www.facebook.com/SoftwareTestingHelp/) [![](data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%20512%20512'%3E%3C/svg%3E)![](https://www.softwaretestinghelp.com/wp-content/themes/generatepress-child/img/linkedin.png)](https://www.linkedin.com/in/shindevijaykr/) [![](data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%20512%20512'%3E%3C/svg%3E)![](https://www.softwaretestinghelp.com/wp-content/themes/generatepress-child/img/twitter.png)](https://twitter.com/vijayshinde) * Learn about our [editorial policies](https://www.softwaretestinghelp.com/editorial-policy-review-process/). Updated April 1, 2025 Overview of Unix Shell Loops and Different Loop Types like: - Unix Do While Loop - Unix For Loop - Unix Until Loop In this tutorial, we will cover the control instructions that are used to iterate a set of commands over a series of data. [![Unix Shell Loops](https://www.softwaretestinghelp.com/wp-content/qa/uploads/2019/10/Unix-Shell-Loops.png)](https://www.softwaretestinghelp.com/wp-content/qa/uploads/2019/10/Unix-Shell-Loops.png) Unix offers three loop structures of which we can repeat a part of a program at a specified number of times. Unix Video \#17: ### Loops in Unix You may use different loops based on the situation. They are: \#1) Unix For loop statement Example: This program will add 1+2+3+4+5 and the result will be 15 ``` for i in 1 2 3 4 5 do sum=`expr $sum + $i` done echo $sum ``` \#2) Unix While loop statement Example: This program will print the value of ‘a’ five times, from 1 to 5. ``` a=1 while [ $a -le 5 ] do echo “value of a=” $a a=`expr $a + 1` done ``` \#3) Unix Until loop statement This program will print the value of ‘a’ two times from 1 to 2. ``` a=1 until [ $a -ge 3 ] do echo “value of a=” $a a=`expr $a + 1` done ``` While running these loops, there may be a need to break out of the loop in some condition before completing all the iterations or to restart the loop before completing the remaining statements. This can be achieved with the ‘break’ and ‘continue’ statements. The following program illustrates the ‘break’ operation: ``` num=1 while [ $num -le 5 ] do read var if [ $var -lt 0 ] then break fi num=`expr $num + 1` done echo “The loop breaks for negative numbers” ``` Our upcoming tutorial will brief you more about working with Functions in Unix. [PREV Tutorial](https://www.softwaretestinghelp.com/unix-switch-case/) \\| [NEXT Tutorial](https://www.softwaretestinghelp.com/unix-functions/) ### Was this helpful? Submit Cancel Thanks for your feedback\! ### Recommended Reading - [Unix Pipes Tutorial: Pipes in Unix Programming](https://www.softwaretestinghelp.com/unix-pipes/) [![Pipes in Unix Programming](data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%20240%20135'%3E%3C/svg%3E)![Pipes in Unix Programming](https://www.softwaretestinghelp.com/wp-content/qa/uploads/2019/10/Pipes-in-Unix-Programming-1.png)](https://www.softwaretestinghelp.com/unix-pipes/) Overview of Pipes in Unix Programming: In this tutorial, we will learn more about Unix Pipes. Later, we will work with some of the remaining filter commands and see an example of piping them together. 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Readable Markdown	By [Vijay](https://www.softwaretestinghelp.com/author/vijay/) By Vijay ![](https://www.softwaretestinghelp.com/wp-content/qa/uploads/2018/12/Vijay-STH-blog-150x150.jpg) I'm Vijay, and I've been working on this blog for the past 20+ years! I’ve been in the IT industry for more than 20 years now. I completed my graduation in B.E. Computer Science from a reputed Pune university and then started my career in… Updated April 1, 2025 Overview of Unix Shell Loops and Different Loop Types like: - Unix Do While Loop - Unix For Loop - Unix Until Loop In this tutorial, we will cover the control instructions that are used to iterate a set of commands over a series of data. [![Unix Shell Loops](https://www.softwaretestinghelp.com/wp-content/qa/uploads/2019/10/Unix-Shell-Loops.png)](https://www.softwaretestinghelp.com/wp-content/qa/uploads/2019/10/Unix-Shell-Loops.png) Unix offers three loop structures of which we can repeat a part of a program at a specified number of times. Unix Video \#17: ### Loops in Unix You may use different loops based on the situation. They are: \#1) Unix For loop statement Example: This program will add 1+2+3+4+5 and the result will be 15 ``` for i in 1 2 3 4 5 do sum=`expr $sum + $i` done echo $sum ``` \#2) Unix While loop statement Example: This program will print the value of ‘a’ five times, from 1 to 5. ``` a=1 while [ $a -le 5 ] do echo “value of a=” $a a=`expr $a + 1` done ``` \#3) Unix Until loop statement This program will print the value of ‘a’ two times from 1 to 2. ``` a=1 until [ $a -ge 3 ] do echo “value of a=” $a a=`expr $a + 1` done ``` While running these loops, there may be a need to break out of the loop in some condition before completing all the iterations or to restart the loop before completing the remaining statements. This can be achieved with the ‘break’ and ‘continue’ statements. The following program illustrates the ‘break’ operation: ``` num=1 while [ $num -le 5 ] do read var if [ $var -lt 0 ] then break fi num=`expr $num + 1` done echo “The loop breaks for negative numbers” ``` *Our upcoming tutorial will brief you more about working with Functions in Unix.* [PREV Tutorial](https://www.softwaretestinghelp.com/unix-switch-case/) \\| [NEXT Tutorial](https://www.softwaretestinghelp.com/unix-functions/) Was this helpful? Thanks for your feedback\! * READ MORE FROM THIS SERIES: - [How to Install Software in Linux (3 Proper Ways)](https://www.softwaretestinghelp.com/3-major-ways-how-to-install-new-software-on-linux/) - [UNIX Tutorial for Beginners (20+ In-depth Unix Training Videos)](https://www.softwaretestinghelp.com/unix-tutorials/) - [Unix Commands: Basic and Advanced Unix Commands with Examples](https://www.softwaretestinghelp.com/unix-commands/) - [Unix File System Commands Touch, Cat, Cp, Mv, Rm, Mkdir (Part B)](https://www.softwaretestinghelp.com/unix-file-system-commands/) - [Unix Processes Control Commands Like Ps and Top (Part C)](https://www.softwaretestinghelp.com/unix-processes-control-command/) - [Unix Utilities Programs Commands: Which, Man, Find Su, Sudo (Part D)](https://www.softwaretestinghelp.com/unix-utilities-programs-commands/) - [File Manipulation in Unix: Overview of Unix File System](https://www.softwaretestinghelp.com/file-manipulation-unix/) - [Unix File Access Permissions: Unix Chmod, Chown and Chgrp](https://www.softwaretestinghelp.com/unix-file-access-permissions/) - [How to Compare Two Files in Unix: File Comparison Commands](https://www.softwaretestinghelp.com/compare-two-files-unix/) - [Unix Special Characters or Metacharacters for File Manipulation](https://www.softwaretestinghelp.com/unix-metacharacters/) - [How to Use Unix Regular Expressions](https://www.softwaretestinghelp.com/unix-regular-expressions/) - [Unix Shell Scripting Tutorial with Examples](https://www.softwaretestinghelp.com/unix-shell-scripting-tutorial/) - [Working with Vi Editor in Unix](https://www.softwaretestinghelp.com/unix-vi-editor/) - [Working with Unix Variables: Features of Shell Scripting](https://www.softwaretestinghelp.com/unix-variables/) - [Unix Shell Script Arithmetic and Boolean Operators Examples](https://www.softwaretestinghelp.com/unix-arithmetic-boolean-operators/) - [Unix Conditional Statements: If Then Else and Relational Operators](https://www.softwaretestinghelp.com/unix-conditional-statements/) - [Using Switch Case in Unix Shell Scripting: Case-esac Statement](https://www.softwaretestinghelp.com/unix-switch-case/) - [Unix Shell Loop Types: Do While Loop, For Loop, Until Loop in Unix](https://www.softwaretestinghelp.com/unix-shell-loops/) - [Unix Shell Script Functions with Parameters and Return](https://www.softwaretestinghelp.com/unix-functions/) - [Unix Text Processing Commands: Unix Filters with Examples](https://www.softwaretestinghelp.com/unix-text-processing-commands/) - [Unix Pipes Tutorial: Pipes in Unix Programming](https://www.softwaretestinghelp.com/unix-pipes/) - [More Unix Filter and Awk, Sed Commands in Text Processing](https://www.softwaretestinghelp.com/unix-filter-awk-sed-commands/) - [Command Line Arguments in Unix Shell Script with Example](https://www.softwaretestinghelp.com/unix-command-line-arguments/) - [Processes in Unix: Process Control and Debugging Commands](https://www.softwaretestinghelp.com/unix-processes/) - [Advanced Unix Shell Scripting: Arrays, File and String Test Operators, Special V…](https://www.softwaretestinghelp.com/advanced-shell-scripting/) - [What is Unix: A Brief Introduction to Unix](https://www.softwaretestinghelp.com/unix-introduction/) - [Unix Vs Linux: What is Difference Between UNIX and Linux](https://www.softwaretestinghelp.com/unix-vs-linux/) - [Unix Permissions: File Permissions in Unix with Examples](https://www.softwaretestinghelp.com/unix-permissions/) - [Grep Command in Unix with Simple Examples](https://www.softwaretestinghelp.com/grep-command-in-unix/) - [Cut Command in Unix with Examples](https://www.softwaretestinghelp.com/cut-command-in-unix/) - [Tar Command in Unix To Create Backups (Examples)](https://www.softwaretestinghelp.com/tar-command-in-unix/) - [Find Command in Unix: Find Files with Unix Find File (Examples)](https://www.softwaretestinghelp.com/find-command-in-unix/) - [Ls Command in Unix with Examples](https://www.softwaretestinghelp.com/ls-command-in-unix/) - [Unix Cat Command Syntax, Options with Examples](https://www.softwaretestinghelp.com/unix-cat-command/) - [Unix Sort Command with Syntax, Options and Examples](https://www.softwaretestinghelp.com/unix-sort-command/) - [Linux vs Windows Difference: Which Is The Best Operating System?](https://www.softwaretestinghelp.com/linux-vs-windows/) - [Linux Commands Tutorial: Learn Basic Linux Commands For Beginners](https://www.softwaretestinghelp.com/linux-commands-tutorial/) - [12 SCP Command Examples To Securely Transfer Files In Linux](https://www.softwaretestinghelp.com/scp-command-tutorial/) - [Ubuntu Vs Windows 10 – Which Is A Better OS](https://www.softwaretestinghelp.com/ubuntu-vs-windows/) *
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