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<!doctype html><html lang=en class=no-js> <head><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><link href=https://flokoe.github.io/bash-hackers-wiki/howto/getopts_tutorial/ rel=canonical><link href=../edit-ed/ rel=prev><link href=../mutex/ rel=next><link rel=icon href=../../assets/images/favicon.png><meta name=generator content="mkdocs-1.6.1, mkdocs-material-9.5.44"><title>Small getopts tutorial - The Bash Hackers Wiki</title><link rel=stylesheet href=../../assets/stylesheets/main.0253249f.min.css><link rel=stylesheet href=../../assets/stylesheets/palette.06af60db.min.css><link rel=preconnect href=https://fonts.gstatic.com crossorigin><link rel=stylesheet href="https://fonts.googleapis.com/css?family=Roboto:300,300i,400,400i,700,700i%7CRoboto+Mono:400,400i,700,700i&display=fallback"><style>:root{--md-text-font:"Roboto";--md-code-font:"Roboto Mono"}</style><script>__md_scope=new 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Dict </a> </li> <li class="md-tabs__item md-tabs__item--active"> <a href=../calculate-dc/ class=md-tabs__link> Howto </a> </li> <li class=md-tabs__item> <a href=../../internals/shell_options/ class=md-tabs__link> Internals </a> </li> <li class=md-tabs__item> <a href=../../misc/bashphorisms/ class=md-tabs__link> Misc </a> </li> <li class=md-tabs__item> <a href=../../scripting/bashbehaviour/ class=md-tabs__link> Scripting </a> </li> <li class=md-tabs__item> <a href=../../snipplets/ class=md-tabs__link> Snipplets </a> </li> <li class=md-tabs__item> <a href=../../syntax/arith_expr/ class=md-tabs__link> Syntax </a> </li> <li class=md-tabs__item> <a href=../../tags/ class=md-tabs__link> Tags </a> </li> </ul> </div> </nav> <main class=md-main data-md-component=main> <div class="md-main__inner md-grid"> <div class="md-sidebar md-sidebar--primary" data-md-component=sidebar data-md-type=navigation> <div class=md-sidebar__scrollwrap> <div class=md-sidebar__inner> <nav class="md-nav 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1-3.3-.7-5.2-1.6-1.6-3.9-2.3-5.2-1m-10.8-8.1c-.7 1.3.3 2.9 2.3 3.9 1.6 1 3.6.7 4.3-.7.7-1.3-.3-2.9-2.3-3.9-2-.6-3.6-.3-4.3.7m32.4 35.6c-1.6 1.3-1 4.3 1.3 6.2 2.3 2.3 5.2 2.6 6.5 1 1.3-1.3.7-4.3-1.3-6.2-2.2-2.3-5.2-2.6-6.5-1m-11.4-14.7c-1.6 1-1.6 3.6 0 5.9s4.3 3.3 5.6 2.3c1.6-1.3 1.6-3.9 0-6.2-1.4-2.3-4-3.3-5.6-2"/></svg> </div> <div class=md-source__repository> flokoe/bash-hackers-wiki </div> </a> </div> <ul class=md-nav__list data-md-scrollfix> <li class=md-nav__item> <a href=../.. class=md-nav__link> <span class=md-ellipsis> Start </span> </a> </li> <li class="md-nav__item md-nav__item--nested"> <input class="md-nav__toggle md-toggle " type=checkbox id=__nav_2> <label class=md-nav__link for=__nav_2 id=__nav_2_label tabindex=0> <span class=md-ellipsis> Commands </span> <span class="md-nav__icon md-icon"></span> </label> <nav class=md-nav data-md-level=1 aria-labelledby=__nav_2_label aria-expanded=false> <label class=md-nav__title for=__nav_2> <span class="md-nav__icon md-icon"></span> Commands </label> <ul class=md-nav__list data-md-scrollfix> <li class=md-nav__item> <a href=../../commands/classictest/ class=md-nav__link> <span class=md-ellipsis> The classic test command </span> </a> </li> <li class="md-nav__item md-nav__item--nested"> <input class="md-nav__toggle md-toggle " type=checkbox id=__nav_2_2> <label class=md-nav__link for=__nav_2_2 id=__nav_2_2_label tabindex=0> <span class=md-ellipsis> Builtin </span> <span class="md-nav__icon md-icon"></span> </label> <nav class=md-nav data-md-level=2 aria-labelledby=__nav_2_2_label aria-expanded=false> <label class=md-nav__title for=__nav_2_2> <span class="md-nav__icon md-icon"></span> Builtin </label> <ul class=md-nav__list data-md-scrollfix> <li class=md-nav__item> <a href=../../commands/builtin/caller/ class=md-nav__link> <span class=md-ellipsis> The caller builtin command </span> </a> </li> <li class=md-nav__item> <a href=../../commands/builtin/cd/ class=md-nav__link> <span class=md-ellipsis> The cd builtin command </span> </a> </li> <li class=md-nav__item> <a href=../../commands/builtin/declare/ class=md-nav__link> <span class=md-ellipsis> The declare builtin command </span> </a> </li> <li class=md-nav__item> <a href=../../commands/builtin/echo/ class=md-nav__link> <span class=md-ellipsis> The echo builtin command </span> </a> </li> <li class=md-nav__item> <a href=../../commands/builtin/eval/ class=md-nav__link> <span class=md-ellipsis> The eval builtin command </span> </a> </li> <li class=md-nav__item> <a href=../../commands/builtin/exec/ class=md-nav__link> <span class=md-ellipsis> The exec builtin command </span> </a> </li> <li class=md-nav__item> <a href=../../commands/builtin/exit/ class=md-nav__link> <span class=md-ellipsis> The exit builtin command </span> </a> </li> <li class=md-nav__item> <a href=../../commands/builtin/export/ class=md-nav__link> <span class=md-ellipsis> The export builtin command </span> </a> </li> <li class=md-nav__item> <a href=../../commands/builtin/kill/ class=md-nav__link> <span class=md-ellipsis> The kill builtin command </span> </a> </li> <li class=md-nav__item> <a href=../../commands/builtin/let/ class=md-nav__link> <span class=md-ellipsis> The let builtin command </span> </a> </li> <li class=md-nav__item> <a href=../../commands/builtin/local/ class=md-nav__link> <span class=md-ellipsis> The local builtin command </span> </a> </li> <li class=md-nav__item> <a href=../../commands/builtin/mapfile/ class=md-nav__link> <span class=md-ellipsis> The mapfile builtin command </span> </a> </li> <li class=md-nav__item> <a href=../../commands/builtin/printf/ class=md-nav__link> <span class=md-ellipsis> The printf command </span> </a> </li> <li class=md-nav__item> <a href=../../commands/builtin/read/ class=md-nav__link> <span class=md-ellipsis> The read builtin command </span> </a> </li> <li class=md-nav__item> <a href=../../commands/builtin/readonly/ class=md-nav__link> <span class=md-ellipsis> The readonly builtin command </span> </a> </li> <li class=md-nav__item> <a href=../../commands/builtin/return/ class=md-nav__link> <span class=md-ellipsis> The return builtin command </span> </a> </li> <li class=md-nav__item> <a href=../../commands/builtin/set/ class=md-nav__link> <span class=md-ellipsis> The set builtin command </span> </a> </li> <li class=md-nav__item> <a href=../../commands/builtin/shift/ class=md-nav__link> <span class=md-ellipsis> The shift builtin command </span> </a> </li> <li class=md-nav__item> <a href=../../commands/builtin/shopt/ class=md-nav__link> <span class=md-ellipsis> The shopt builtin command </span> </a> </li> <li class=md-nav__item> <a href=../../commands/builtin/trap/ class=md-nav__link> <span class=md-ellipsis> The trap builtin command </span> </a> </li> <li class=md-nav__item> <a href=../../commands/builtin/unset/ class=md-nav__link> <span class=md-ellipsis> The unset builtin command </span> </a> </li> <li class=md-nav__item> <a href=../../commands/builtin/wait/ class=md-nav__link> <span class=md-ellipsis> The wait builtin command </span> </a> </li> </ul> </nav> </li> </ul> </nav> </li> <li class="md-nav__item md-nav__item--nested"> <input class="md-nav__toggle md-toggle " type=checkbox id=__nav_3> <label class=md-nav__link for=__nav_3 id=__nav_3_label tabindex=0> <span class=md-ellipsis> Dict </span> <span class="md-nav__icon md-icon"></span> </label> <nav class=md-nav data-md-level=1 aria-labelledby=__nav_3_label aria-expanded=false> <label class=md-nav__title for=__nav_3> <span class="md-nav__icon md-icon"></span> Dict </label> <ul class=md-nav__list data-md-scrollfix> <li class=md-nav__item> <a href=../../dict/directory/ class=md-nav__link> <span class=md-ellipsis> Directory </span> </a> </li> <li class=md-nav__item> <a href=../../dict/end_of_options/ class=md-nav__link> <span class=md-ellipsis> End of Options </span> </a> </li> <li class=md-nav__item> <a href=../../dict/exit_status/ class=md-nav__link> <span class=md-ellipsis> Exit Status </span> </a> </li> <li class=md-nav__item> <a href=../../dict/file/ class=md-nav__link> <span class=md-ellipsis> File </span> </a> </li> <li class=md-nav__item> <a href=../../dict/filetimes/ class=md-nav__link> <span class=md-ellipsis> File timestamp </span> </a> </li> <li class=md-nav__item> <a href=../../dict/globbing/ class=md-nav__link> <span class=md-ellipsis> Globbing </span> </a> </li> <li class=md-nav__item> <a href=../../dict/hardlink/ class=md-nav__link> <span class=md-ellipsis> Hardlink </span> </a> </li> <li class=md-nav__item> <a href=../../dict/interpreter_directive/ class=md-nav__link> <span class=md-ellipsis> Interpreter Directive </span> </a> </li> <li class=md-nav__item> <a href=../../dict/parameter/ class=md-nav__link> <span class=md-ellipsis> Parameter </span> </a> </li> <li class=md-nav__item> <a href=../../dict/posix/ class=md-nav__link> <span class=md-ellipsis> POSIX </span> </a> </li> <li class=md-nav__item> <a href=../../dict/shell/ class=md-nav__link> <span class=md-ellipsis> Shell </span> </a> </li> <li class=md-nav__item> <a href=../../dict/special_file/ class=md-nav__link> <span class=md-ellipsis> Special file </span> </a> </li> <li class=md-nav__item> <a href=../../dict/symlink/ class=md-nav__link> <span class=md-ellipsis> Symlink </span> </a> </li> </ul> </nav> </li> <li class="md-nav__item md-nav__item--active md-nav__item--section md-nav__item--nested"> <input class="md-nav__toggle md-toggle " type=checkbox id=__nav_4 checked> <label class=md-nav__link for=__nav_4 id=__nav_4_label tabindex> <span class=md-ellipsis> Howto </span> <span class="md-nav__icon md-icon"></span> </label> <nav class=md-nav data-md-level=1 aria-labelledby=__nav_4_label aria-expanded=true> <label class=md-nav__title for=__nav_4> <span class="md-nav__icon md-icon"></span> Howto </label> <ul class=md-nav__list data-md-scrollfix> <li class=md-nav__item> <a href=../calculate-dc/ class=md-nav__link> <span class=md-ellipsis> Calculating with dc </span> </a> </li> <li class=md-nav__item> <a href=../collapsing_functions/ class=md-nav__link> <span class=md-ellipsis> Collapsing Functions </span> </a> </li> <li class=md-nav__item> <a href=../conffile/ class=md-nav__link> <span class=md-ellipsis> Config files for your script </span> </a> </li> <li class=md-nav__item> <a href=../dissectabadoneliner/ class=md-nav__link> <span class=md-ellipsis> Dissect a bad oneliner </span> </a> </li> <li class=md-nav__item> <a href=../edit-ed/ class=md-nav__link> <span class=md-ellipsis> Editing files via scripts with ed </span> </a> </li> <li class="md-nav__item md-nav__item--active"> <input class="md-nav__toggle md-toggle" type=checkbox id=__toc> <label class="md-nav__link md-nav__link--active" for=__toc> <span class=md-ellipsis> Small getopts tutorial </span> <span class="md-nav__icon md-icon"></span> </label> <a href=./ class="md-nav__link md-nav__link--active"> <span class=md-ellipsis> Small getopts tutorial </span> </a> <nav class="md-nav md-nav--secondary" aria-label="Table of contents"> <label class=md-nav__title for=__toc> <span class="md-nav__icon md-icon"></span> Table of contents </label> <ul class=md-nav__list data-md-component=toc data-md-scrollfix> <li class=md-nav__item> <a href=#description class=md-nav__link> <span class=md-ellipsis> Description </span> </a> <nav class=md-nav aria-label=Description> <ul class=md-nav__list> <li class=md-nav__item> <a href=#terminology class=md-nav__link> <span class=md-ellipsis> Terminology </span> </a> </li> <li class=md-nav__item> <a href=#how-it-works class=md-nav__link> <span class=md-ellipsis> How it works </span> </a> </li> <li class=md-nav__item> <a href=#used-variables class=md-nav__link> <span class=md-ellipsis> Used variables </span> </a> </li> <li class=md-nav__item> <a href=#specify-what-you-want class=md-nav__link> <span class=md-ellipsis> Specify what you want </span> </a> <nav class=md-nav aria-label="Specify what you want"> <ul class=md-nav__list> <li class=md-nav__item> <a href=#the-option-string class=md-nav__link> <span class=md-ellipsis> The option-string </span> </a> </li> <li class=md-nav__item> <a href=#custom-arguments-to-parse class=md-nav__link> <span class=md-ellipsis> Custom arguments to parse </span> </a> </li> </ul> </nav> </li> <li class=md-nav__item> <a href=#error-reporting class=md-nav__link> <span class=md-ellipsis> Error Reporting </span> </a> <nav class=md-nav aria-label="Error Reporting"> <ul class=md-nav__list> <li class=md-nav__item> <a href=#verbose-mode class=md-nav__link> <span class=md-ellipsis> Verbose Mode </span> </a> </li> <li class=md-nav__item> <a href=#silent-mode class=md-nav__link> <span class=md-ellipsis> Silent Mode </span> </a> </li> </ul> </nav> </li> </ul> </nav> </li> <li class=md-nav__item> <a href=#using-it class=md-nav__link> <span class=md-ellipsis> Using it </span> </a> <nav class=md-nav aria-label="Using it"> <ul class=md-nav__list> <li class=md-nav__item> <a href=#a-first-example class=md-nav__link> <span class=md-ellipsis> A first example </span> </a> <nav class=md-nav aria-label="A first example"> <ul class=md-nav__list> <li class=md-nav__item> <a href=#calling-it-without-any-arguments class=md-nav__link> <span class=md-ellipsis> Calling it without any arguments </span> </a> </li> <li class=md-nav__item> <a href=#calling-it-with-non-option-arguments class=md-nav__link> <span class=md-ellipsis> Calling it with non-option arguments </span> </a> </li> <li class=md-nav__item> <a href=#calling-it-with-option-arguments class=md-nav__link> <span class=md-ellipsis> Calling it with option-arguments </span> </a> </li> </ul> </nav> </li> <li class=md-nav__item> <a href=#an-option-with-argument class=md-nav__link> <span class=md-ellipsis> An option with argument </span> </a> <nav class=md-nav aria-label="An option with argument"> <ul class=md-nav__list> <li class=md-nav__item> <a href=#calling-it-without-any-arguments_1 class=md-nav__link> <span class=md-ellipsis> Calling it without any arguments </span> </a> </li> <li class=md-nav__item> <a href=#calling-it-with-non-option-arguments_1 class=md-nav__link> <span class=md-ellipsis> Calling it with non-option arguments </span> </a> </li> <li class=md-nav__item> <a href=#calling-it-with-option-arguments_1 class=md-nav__link> <span class=md-ellipsis> Calling it with option-arguments </span> </a> </li> </ul> </nav> </li> </ul> </nav> </li> <li class=md-nav__item> <a href=#see-also class=md-nav__link> <span class=md-ellipsis> See also </span> </a> </li> </ul> </nav> </li> <li class=md-nav__item> <a href=../mutex/ class=md-nav__link> <span class=md-ellipsis> Lock your script (against parallel execution) </span> </a> </li> <li class=md-nav__item> <a href=../pax/ class=md-nav__link> <span class=md-ellipsis> pax - the POSIX archiver </span> </a> </li> <li class=md-nav__item> <a href=../redirection_tutorial/ class=md-nav__link> <span class=md-ellipsis> Illustrated Redirection Tutorial </span> </a> </li> <li class=md-nav__item> <a href=../testing-your-scripts/ class=md-nav__link> <span class=md-ellipsis> Testing your scripts </span> </a> </li> </ul> </nav> </li> <li class="md-nav__item md-nav__item--nested"> <input class="md-nav__toggle md-toggle " type=checkbox id=__nav_5> <label class=md-nav__link for=__nav_5 id=__nav_5_label tabindex=0> <span class=md-ellipsis> Internals </span> <span class="md-nav__icon md-icon"></span> </label> <nav class=md-nav data-md-level=1 aria-labelledby=__nav_5_label aria-expanded=false> <label class=md-nav__title for=__nav_5> <span class="md-nav__icon md-icon"></span> Internals </label> <ul class=md-nav__list data-md-scrollfix> <li class=md-nav__item> <a href=../../internals/shell_options/ class=md-nav__link> <span class=md-ellipsis> List of shell options </span> </a> </li> </ul> </nav> </li> <li class="md-nav__item md-nav__item--nested"> <input class="md-nav__toggle md-toggle " type=checkbox id=__nav_6> <label class=md-nav__link for=__nav_6 id=__nav_6_label tabindex=0> <span class=md-ellipsis> Misc </span> <span class="md-nav__icon md-icon"></span> </label> <nav class=md-nav data-md-level=1 aria-labelledby=__nav_6_label aria-expanded=false> <label class=md-nav__title for=__nav_6> <span class="md-nav__icon md-icon"></span> Misc </label> <ul class=md-nav__list data-md-scrollfix> <li class=md-nav__item> <a href=../../misc/bashphorisms/ class=md-nav__link> <span class=md-ellipsis> The Bashphorisms </span> </a> </li> <li class=md-nav__item> <a href=../../misc/readthesourceluke/ class=md-nav__link> <span class=md-ellipsis> Readthesourceluke </span> </a> </li> <li class=md-nav__item> <a href=../../misc/shell_humor/ class=md-nav__link> <span class=md-ellipsis> Shell Humor </span> </a> </li> </ul> </nav> </li> <li class="md-nav__item md-nav__item--nested"> <input class="md-nav__toggle md-toggle " type=checkbox id=__nav_7> <label class=md-nav__link for=__nav_7 id=__nav_7_label tabindex=0> <span class=md-ellipsis> Scripting </span> <span class="md-nav__icon md-icon"></span> </label> <nav class=md-nav data-md-level=1 aria-labelledby=__nav_7_label aria-expanded=false> <label class=md-nav__title for=__nav_7> <span class="md-nav__icon md-icon"></span> Scripting </label> <ul class=md-nav__list data-md-scrollfix> <li class=md-nav__item> <a href=../../scripting/bashbehaviour/ class=md-nav__link> <span class=md-ellipsis> Bash's behaviour </span> </a> </li> <li class=md-nav__item> <a href=../../scripting/bashchanges/ class=md-nav__link> <span class=md-ellipsis> Bash changes </span> </a> </li> <li class=md-nav__item> <a href=../../scripting/basics/ class=md-nav__link> <span class=md-ellipsis> The basics of shell scripting </span> </a> </li> <li class=md-nav__item> <a href=../../scripting/debuggingtips/ class=md-nav__link> <span class=md-ellipsis> Debugging a script </span> </a> </li> <li class=md-nav__item> <a href=../../scripting/newbie_traps/ class=md-nav__link> <span class=md-ellipsis> Beginner Mistakes </span> </a> </li> <li class=md-nav__item> <a href=../../scripting/nonportable/ class=md-nav__link> <span class=md-ellipsis> Portability talk </span> </a> </li> <li class=md-nav__item> <a href=../../scripting/obsolete/ class=md-nav__link> <span class=md-ellipsis> Obsolete and deprecated syntax </span> </a> </li> <li class=md-nav__item> <a href=../../scripting/posparams/ class=md-nav__link> <span class=md-ellipsis> Handling positional parameters </span> </a> </li> <li class=md-nav__item> <a href=../../scripting/processtree/ class=md-nav__link> <span class=md-ellipsis> Bash and the process tree </span> </a> </li> <li class=md-nav__item> <a href=../../scripting/style/ class=md-nav__link> <span class=md-ellipsis> Scripting with style </span> </a> </li> <li class=md-nav__item> <a href=../../scripting/terminalcodes/ class=md-nav__link> <span class=md-ellipsis> Terminal codes (ANSI/VT100) introduction </span> </a> </li> </ul> </nav> </li> <li class="md-nav__item md-nav__item--nested"> <input class="md-nav__toggle md-toggle " type=checkbox id=__nav_8> <label class=md-nav__link for=__nav_8 id=__nav_8_label tabindex=0> <span class=md-ellipsis> Snipplets </span> <span class="md-nav__icon md-icon"></span> </label> <nav class=md-nav data-md-level=1 aria-labelledby=__nav_8_label aria-expanded=false> <label class=md-nav__title for=__nav_8> <span class="md-nav__icon md-icon"></span> Snipplets </label> <ul class=md-nav__list data-md-scrollfix> <li class=md-nav__item> <a href=../../snipplets/ class=md-nav__link> <span class=md-ellipsis> Small code snipplets </span> </a> </li> <li class=md-nav__item> <a href=../../snipplets/add_color_to_your_scripts/ class=md-nav__link> <span class=md-ellipsis> Add Color to your scripts </span> </a> </li> <li class=md-nav__item> <a href=../../snipplets/awkcsv/ class=md-nav__link> <span class=md-ellipsis> Using awk to deal with CSV that uses quoted/unquoted delimiters </span> </a> </li> <li class=md-nav__item> <a href=../../snipplets/filesize/ class=md-nav__link> <span class=md-ellipsis> Show size of a file </span> </a> </li> <li class=md-nav__item> <a href=../../snipplets/kill_bg_job_without_message/ class=md-nav__link> <span class=md-ellipsis> Kill a background job without a message </span> </a> </li> <li class=md-nav__item> <a href=../../snipplets/largestfile/ class=md-nav__link> <span class=md-ellipsis> Get largest file </span> </a> </li> <li class=md-nav__item> <a href=../../snipplets/pause_command/ class=md-nav__link> <span class=md-ellipsis> Pausing a script (like MSDOS pause command) </span> </a> </li> <li class=md-nav__item> <a href=../../snipplets/prargs/ class=md-nav__link> <span class=md-ellipsis> Print argument list for testing </span> </a> </li> <li class=md-nav__item> <a href=../../snipplets/print_horizontal_line/ class=md-nav__link> <span class=md-ellipsis> Print a horizontal line </span> </a> </li> <li class=md-nav__item> <a href=../../snipplets/rndstr/ class=md-nav__link> <span class=md-ellipsis> Print a random string or select random elements </span> </a> </li> <li class=md-nav__item> <a href=../../snipplets/screen_saverestore/ class=md-nav__link> <span class=md-ellipsis> Save and restore terminal/screen content </span> </a> </li> <li class=md-nav__item> <a href=../../snipplets/ssh_fetchkeys/ class=md-nav__link> <span class=md-ellipsis> Fetching SSH hostkeys without interaction </span> </a> </li> <li class=md-nav__item> <a href=../../snipplets/ssh_local_var/ class=md-nav__link> <span class=md-ellipsis> Run some bash commands with SSH remotely using local variables </span> </a> </li> <li class=md-nav__item> <a href=../../snipplets/wrapperargs/ class=md-nav__link> <span class=md-ellipsis> Generate code with own arguments properly quoted </span> </a> </li> <li class=md-nav__item> <a href=../../snipplets/xclip/ class=md-nav__link> <span class=md-ellipsis> X-Clipboard on Commandline </span> </a> </li> </ul> </nav> </li> <li class="md-nav__item md-nav__item--nested"> <input class="md-nav__toggle md-toggle " type=checkbox id=__nav_9> <label class=md-nav__link for=__nav_9 id=__nav_9_label tabindex=0> <span class=md-ellipsis> Syntax </span> <span class="md-nav__icon md-icon"></span> </label> <nav class=md-nav data-md-level=1 aria-labelledby=__nav_9_label aria-expanded=false> <label class=md-nav__title for=__nav_9> <span class="md-nav__icon md-icon"></span> Syntax </label> <ul class=md-nav__list data-md-scrollfix> <li class=md-nav__item> <a href=../../syntax/arith_expr/ class=md-nav__link> <span class=md-ellipsis> Arithmetic expressions </span> </a> </li> <li class=md-nav__item> <a href=../../syntax/arrays/ class=md-nav__link> <span class=md-ellipsis> Arrays </span> </a> </li> <li class=md-nav__item> <a href=../../syntax/basicgrammar/ class=md-nav__link> <span class=md-ellipsis> Basic grammar rules of Bash </span> </a> </li> <li class=md-nav__item> <a href=../../syntax/pattern/ class=md-nav__link> <span class=md-ellipsis> Patterns and pattern matching </span> </a> </li> <li class=md-nav__item> <a href=../../syntax/pe/ class=md-nav__link> <span class=md-ellipsis> Parameter expansion </span> </a> </li> <li class=md-nav__item> <a href=../../syntax/quoting/ class=md-nav__link> <span class=md-ellipsis> Quotes and escaping </span> </a> </li> <li class=md-nav__item> <a href=../../syntax/redirection/ class=md-nav__link> <span class=md-ellipsis> Redirection </span> </a> </li> <li class=md-nav__item> <a href=../../syntax/shellvars/ class=md-nav__link> <span class=md-ellipsis> Special parameters and shell variables </span> </a> </li> <li class=md-nav__item> <a href=../../syntax/words/ class=md-nav__link> <span class=md-ellipsis> Words... </span> </a> </li> <li class="md-nav__item md-nav__item--nested"> <input class="md-nav__toggle md-toggle " type=checkbox id=__nav_9_10> <label class=md-nav__link for=__nav_9_10 id=__nav_9_10_label tabindex=0> <span class=md-ellipsis> Ccmd </span> <span class="md-nav__icon md-icon"></span> </label> <nav class=md-nav data-md-level=2 aria-labelledby=__nav_9_10_label aria-expanded=false> <label class=md-nav__title for=__nav_9_10> <span class="md-nav__icon md-icon"></span> Ccmd </label> <ul class=md-nav__list data-md-scrollfix> <li class=md-nav__item> <a href=../../syntax/ccmd/arithmetic_eval/ class=md-nav__link> <span class=md-ellipsis> Arithmetic evaluation (command) </span> </a> </li> <li class=md-nav__item> <a href=../../syntax/ccmd/c_for/ class=md-nav__link> <span class=md-ellipsis> The C-style for-loop </span> </a> </li> <li class=md-nav__item> <a href=../../syntax/ccmd/case/ class=md-nav__link> <span class=md-ellipsis> The case statement </span> </a> </li> <li class=md-nav__item> <a href=../../syntax/ccmd/classic_for/ class=md-nav__link> <span class=md-ellipsis> The classic for-loop </span> </a> </li> <li class=md-nav__item> <a href=../../syntax/ccmd/conditional_expression/ class=md-nav__link> <span class=md-ellipsis> The conditional expression </span> </a> </li> <li class=md-nav__item> <a href=../../syntax/ccmd/grouping_plain/ class=md-nav__link> <span class=md-ellipsis> Grouping commands </span> </a> </li> <li class=md-nav__item> <a href=../../syntax/ccmd/grouping_subshell/ class=md-nav__link> <span class=md-ellipsis> Grouping commands in a subshell </span> </a> </li> <li class=md-nav__item> <a href=../../syntax/ccmd/if_clause/ class=md-nav__link> <span class=md-ellipsis> The if-clause </span> </a> </li> <li class=md-nav__item> <a href=../../syntax/ccmd/intro/ class=md-nav__link> <span class=md-ellipsis> Bash compound commands </span> </a> </li> <li class=md-nav__item> <a href=../../syntax/ccmd/until_loop/ class=md-nav__link> <span class=md-ellipsis> The until loop </span> </a> </li> <li class=md-nav__item> <a href=../../syntax/ccmd/user_select/ class=md-nav__link> <span class=md-ellipsis> User selections </span> </a> </li> <li class=md-nav__item> <a href=../../syntax/ccmd/while_loop/ class=md-nav__link> <span class=md-ellipsis> The while-loop </span> </a> </li> </ul> </nav> </li> <li class="md-nav__item md-nav__item--nested"> <input class="md-nav__toggle md-toggle " type=checkbox id=__nav_9_11> <label class=md-nav__link for=__nav_9_11 id=__nav_9_11_label tabindex=0> <span class=md-ellipsis> Expansion </span> <span class="md-nav__icon md-icon"></span> </label> <nav class=md-nav data-md-level=2 aria-labelledby=__nav_9_11_label aria-expanded=false> <label class=md-nav__title for=__nav_9_11> <span class="md-nav__icon md-icon"></span> Expansion </label> <ul class=md-nav__list data-md-scrollfix> <li class=md-nav__item> <a href=../../syntax/expansion/arith/ class=md-nav__link> <span class=md-ellipsis> Arithmetic expansion </span> </a> </li> <li class=md-nav__item> <a href=../../syntax/expansion/brace/ class=md-nav__link> <span class=md-ellipsis> Brace expansion </span> </a> </li> <li class=md-nav__item> <a href=../../syntax/expansion/cmdsubst/ class=md-nav__link> <span class=md-ellipsis> Command substitution </span> </a> </li> <li class=md-nav__item> <a href=../../syntax/expansion/globs/ class=md-nav__link> <span class=md-ellipsis> Pathname expansion (globbing) </span> </a> </li> <li class=md-nav__item> <a href=../../syntax/expansion/intro/ class=md-nav__link> <span class=md-ellipsis> Expansions and substitutions </span> </a> </li> <li class=md-nav__item> <a href=../../syntax/expansion/proc_subst/ class=md-nav__link> <span class=md-ellipsis> Process substitution </span> </a> </li> <li class=md-nav__item> <a href=../../syntax/expansion/tilde/ class=md-nav__link> <span class=md-ellipsis> Tilde expansion </span> </a> </li> <li class=md-nav__item> <a href=../../syntax/expansion/wordsplit/ class=md-nav__link> <span class=md-ellipsis> Word splitting </span> </a> </li> </ul> </nav> </li> <li class="md-nav__item md-nav__item--nested"> <input class="md-nav__toggle md-toggle " type=checkbox id=__nav_9_12> <label class=md-nav__link for=__nav_9_12 id=__nav_9_12_label tabindex=0> <span class=md-ellipsis> Grammar </span> <span class="md-nav__icon md-icon"></span> </label> <nav class=md-nav data-md-level=2 aria-labelledby=__nav_9_12_label aria-expanded=false> <label class=md-nav__title for=__nav_9_12> <span class="md-nav__icon md-icon"></span> Grammar </label> <ul class=md-nav__list data-md-scrollfix> <li class=md-nav__item> <a href=../../syntax/grammar/parser_exec/ class=md-nav__link> <span class=md-ellipsis> Parser exec </span> </a> </li> </ul> </nav> </li> <li class="md-nav__item md-nav__item--nested"> <input class="md-nav__toggle md-toggle " type=checkbox id=__nav_9_13> <label class=md-nav__link for=__nav_9_13 id=__nav_9_13_label tabindex=0> <span class=md-ellipsis> Keywords </span> <span class="md-nav__icon md-icon"></span> </label> <nav class=md-nav data-md-level=2 aria-labelledby=__nav_9_13_label aria-expanded=false> <label class=md-nav__title for=__nav_9_13> <span class="md-nav__icon md-icon"></span> Keywords </label> <ul class=md-nav__list data-md-scrollfix> <li class=md-nav__item> <a href=../../syntax/keywords/coproc/ class=md-nav__link> <span class=md-ellipsis> The coproc keyword </span> </a> </li> </ul> </nav> </li> </ul> </nav> </li> <li class=md-nav__item> <a href=../../tags/ class=md-nav__link> <span class=md-ellipsis> Tags </span> </a> </li> </ul> </nav> </div> </div> </div> <div class="md-sidebar md-sidebar--secondary" data-md-component=sidebar data-md-type=toc> <div class=md-sidebar__scrollwrap> <div class=md-sidebar__inner> <nav class="md-nav md-nav--secondary" aria-label="Table of contents"> <label class=md-nav__title for=__toc> <span class="md-nav__icon md-icon"></span> Table of contents </label> <ul class=md-nav__list data-md-component=toc data-md-scrollfix> <li class=md-nav__item> <a href=#description class=md-nav__link> <span class=md-ellipsis> Description </span> </a> <nav class=md-nav aria-label=Description> <ul class=md-nav__list> <li class=md-nav__item> <a href=#terminology class=md-nav__link> <span class=md-ellipsis> Terminology </span> </a> </li> <li class=md-nav__item> <a href=#how-it-works class=md-nav__link> <span class=md-ellipsis> How it works </span> </a> </li> <li class=md-nav__item> <a href=#used-variables class=md-nav__link> <span class=md-ellipsis> Used variables </span> </a> </li> <li class=md-nav__item> <a href=#specify-what-you-want class=md-nav__link> <span class=md-ellipsis> Specify what you want </span> </a> <nav class=md-nav aria-label="Specify what you want"> <ul class=md-nav__list> <li class=md-nav__item> <a href=#the-option-string class=md-nav__link> <span class=md-ellipsis> The option-string </span> </a> </li> <li class=md-nav__item> <a href=#custom-arguments-to-parse class=md-nav__link> <span class=md-ellipsis> Custom arguments to parse </span> </a> </li> </ul> </nav> </li> <li class=md-nav__item> <a href=#error-reporting class=md-nav__link> <span class=md-ellipsis> Error Reporting </span> </a> <nav class=md-nav aria-label="Error Reporting"> <ul class=md-nav__list> <li class=md-nav__item> <a href=#verbose-mode class=md-nav__link> <span class=md-ellipsis> Verbose Mode </span> </a> </li> <li class=md-nav__item> <a href=#silent-mode class=md-nav__link> <span class=md-ellipsis> Silent Mode </span> </a> </li> </ul> </nav> </li> </ul> </nav> </li> <li class=md-nav__item> <a href=#using-it class=md-nav__link> <span class=md-ellipsis> Using it </span> </a> <nav class=md-nav aria-label="Using it"> <ul class=md-nav__list> <li class=md-nav__item> <a href=#a-first-example class=md-nav__link> <span class=md-ellipsis> A first example </span> </a> <nav class=md-nav aria-label="A first example"> <ul class=md-nav__list> <li class=md-nav__item> <a href=#calling-it-without-any-arguments class=md-nav__link> <span class=md-ellipsis> Calling it without any arguments </span> </a> </li> <li class=md-nav__item> <a href=#calling-it-with-non-option-arguments class=md-nav__link> <span class=md-ellipsis> Calling it with non-option arguments </span> </a> </li> <li class=md-nav__item> <a href=#calling-it-with-option-arguments class=md-nav__link> <span class=md-ellipsis> Calling it with option-arguments </span> </a> </li> </ul> </nav> </li> <li class=md-nav__item> <a href=#an-option-with-argument class=md-nav__link> <span class=md-ellipsis> An option with argument </span> </a> <nav class=md-nav aria-label="An option with argument"> <ul class=md-nav__list> <li class=md-nav__item> <a href=#calling-it-without-any-arguments_1 class=md-nav__link> <span class=md-ellipsis> Calling it without any arguments </span> </a> </li> <li class=md-nav__item> <a href=#calling-it-with-non-option-arguments_1 class=md-nav__link> <span class=md-ellipsis> Calling it with non-option arguments </span> </a> </li> <li class=md-nav__item> <a href=#calling-it-with-option-arguments_1 class=md-nav__link> <span class=md-ellipsis> Calling it with option-arguments </span> </a> </li> </ul> </nav> </li> </ul> </nav> </li> <li class=md-nav__item> <a href=#see-also class=md-nav__link> <span class=md-ellipsis> See also </span> </a> </li> </ul> </nav> </div> </div> </div> <div class=md-content data-md-component=content> <article class="md-content__inner md-typeset"> <nav class=md-tags> <a href=../../tags/#bash class=md-tag>bash</a> <a href=../../tags/#shell class=md-tag>shell</a> <a href=../../tags/#scripting class=md-tag>scripting</a> <a href=../../tags/#arguments class=md-tag>arguments</a> <a href=../../tags/#positional class=md-tag>positional</a> <a href=../../tags/#parameters class=md-tag>parameters</a> <a href=../../tags/#options class=md-tag>options</a> <a href=../../tags/#getopt class=md-tag>getopt</a> <a href=../../tags/#getopts class=md-tag>getopts</a> </nav> <a href=https://github.com/flokoe/bash-hackers-wiki/edit/main/docs/howto/getopts_tutorial.md title="Edit this page" class="md-content__button md-icon"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M10 20H6V4h7v5h5v3.1l2-2V8l-6-6H6c-1.1 0-2 .9-2 2v16c0 1.1.9 2 2 2h4zm10.2-7c.1 0 .3.1.4.2l1.3 1.3c.2.2.2.6 0 .8l-1 1-2.1-2.1 1-1c.1-.1.2-.2.4-.2m0 3.9L14.1 23H12v-2.1l6.1-6.1z"/></svg> </a> <a href=https://github.com/flokoe/bash-hackers-wiki/raw/main/docs/howto/getopts_tutorial.md title="View source of this page" class="md-content__button md-icon"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M17 18c.56 0 1 .44 1 1s-.44 1-1 1-1-.44-1-1 .44-1 1-1m0-3c-2.73 0-5.06 1.66-6 4 .94 2.34 3.27 4 6 4s5.06-1.66 6-4c-.94-2.34-3.27-4-6-4m0 6.5a2.5 2.5 0 0 1-2.5-2.5 2.5 2.5 0 0 1 2.5-2.5 2.5 2.5 0 0 1 2.5 2.5 2.5 2.5 0 0 1-2.5 2.5M9.27 20H6V4h7v5h5v4.07c.7.08 1.36.25 2 .49V8l-6-6H6a2 2 0 0 0-2 2v16a2 2 0 0 0 2 2h4.5a8.2 8.2 0 0 1-1.23-2"/></svg> </a> <h1 id=small-getopts-tutorial>Small getopts tutorial<a class=headerlink href=#small-getopts-tutorial title="Permanent link">&para;</a></h1> <h2 id=description>Description<a class=headerlink href=#description title="Permanent link">&para;</a></h2> <p><strong>Note that</strong> <code>getopts</code> is neither able to parse GNU-style long options (<code>--myoption</code>) nor XF86-style long options (<code>-myoption</code>). So, when you want to parse command line arguments in a professional ;-) way, <code>getopts</code> may or may not work for you. Unlike its older brother <code>getopt</code> (note the missing <em>s</em>!), it's a shell builtin command. The advantages are:</p> <ul> <li>No need to pass the positional parameters through to an external program.</li> <li>Being a builtin, <code>getopts</code> can set shell variables to use for parsing (impossible for an <em>external</em> process!)</li> <li>There's no need to argue with several <code>getopt</code> implementations which had buggy concepts in the past (whitespace, ...)</li> <li><code>getopts</code> is defined in POSIX&reg;.</li> </ul> <hr> <p>Some other methods to parse positional parameters - using neither <strong>getopt</strong> nor <strong>getopts</strong> - are described in: <a href=../../scripting/posparams/ >How to handle positional parameters</a>.</p> <h3 id=terminology>Terminology<a class=headerlink href=#terminology title="Permanent link">&para;</a></h3> <p>It's useful to know what we're talking about here, so let's see... Consider the following command line:</p> <div class=highlight><pre><span></span><code>mybackup -x -f /etc/mybackup.conf -r ./foo.txt ./bar.txt
</code></pre></div> <p>These are all positional parameters, but they can be divided into several logical groups:</p> <ul> <li><code>-x</code> is an <strong>option</strong> (aka <strong>flag</strong> or <strong>switch</strong>). It consists of a dash (<code>-</code>) followed by <strong>one</strong> character.</li> <li><code>-f</code> is also an option, but this option has an associated <strong>option argument</strong> (an argument to the option <code>-f</code>): <code>/etc/mybackup.conf</code>. The option argument is usually the argument following the option itself, but that isn't mandatory. Joining the option and option argument into a single argument <code>-f/etc/mybackup.conf</code> is valid.</li> <li><code>-r</code> depends on the configuration. In this example, <code>-r</code> doesn't take arguments so it's a standalone option like <code>-x</code>.</li> <li><code>./foo.txt</code> and <code>./bar.txt</code> are remaining arguments without any associated options. These are often used as <strong>mass-arguments</strong>. For example, the filenames specified for <code>cp(1)</code>, or arguments that don't need an option to be recognized because of the intended behavior of the program. POSIX&reg; calls them <strong>operands</strong>.</li> </ul> <p>To give you an idea about why <code>getopts</code> is useful, The above command line is equivalent to:</p> <div class=highlight><pre><span></span><code>mybackup -xrf /etc/mybackup.conf ./foo.txt ./bar.txt
</code></pre></div> <p>which is complex to parse without the help of <code>getopts</code>.</p> <p>The option flags can be <strong>upper- and lowercase</strong> characters, or <strong>digits</strong>. It may recognize other characters, but that's not recommended (usability and maybe problems with special characters).</p> <h3 id=how-it-works>How it works<a class=headerlink href=#how-it-works title="Permanent link">&para;</a></h3> <p>In general you need to call <code>getopts</code> several times. Each time it will use the next positional parameter and a possible argument, if parsable, and provide it to you. <code>getopts</code> will not change the set of positional parameters. If you want to shift them, it must be done manually:</p> <div class=highlight><pre><span></span><code>shift $((OPTIND-1))
# now do something with $@
</code></pre></div> <p>Since <code>getopts</code> sets an exit status of <em>FALSE</em> when there's nothing left to parse, it's easy to use in a while-loop:</p> <div class=highlight><pre><span></span><code>while getopts ...; do
...
done
</code></pre></div> <p><code>getopts</code> will parse options and their possible arguments. It will stop parsing on the first non-option argument (a string that doesn't begin with a hyphen (<code>-</code>) that isn't an argument for any option in front of it). It will also stop parsing when it sees the <code>--</code> (double-hyphen), which means <a href=../../dict/end_of_options/ >end of options</a>.</p> <h3 id=used-variables>Used variables<a class=headerlink href=#used-variables title="Permanent link">&para;</a></h3> <table> <thead> <tr> <th>variable</th> <th>description</th> </tr> </thead> <tbody> <tr> <td><a href=../../syntax/shellvars/#OPTIND>OPTIND</a></td> <td>Holds the index to the next argument to be processed. This is how <code>getopts</code> "remembers" its own status between invocations. Also useful to shift the positional parameters after processing with <code>getopts</code>. <code>OPTIND</code> is initially set to 1, and <strong>needs to be re-set to 1 if you want to parse anything again with getopts</strong></td> </tr> <tr> <td><a href=../../syntax/shellvars/#OPTARG>OPTARG</a></td> <td>This variable is set to any argument for an option found by <code>getopts</code>. It also contains the option flag of an unknown option.</td> </tr> <tr> <td><a href=../../syntax/shellvars/#OPTERR>OPTERR</a></td> <td>(Values 0 or 1) Indicates if Bash should display error messages generated by the <code>getopts</code> builtin. The value is initialized to <strong>1</strong> on every shell startup - so be sure to always set it to <strong>0</strong> if you don't want to see annoying messages! <strong><code>OPTERR</code> is not specified by POSIX for the <code>getopts</code> builtin utility --- only for the C <code>getopt()</code> function in <code>unistd.h</code> (<code>opterr</code>).</strong> <code>OPTERR</code> is bash-specific and not supported by shells such as ksh93, mksh, zsh, or dash.</td> </tr> </tbody> </table> <p><code>getopts</code> also uses these variables for error reporting (they're set to value-combinations which arent possible in normal operation).</p> <h3 id=specify-what-you-want>Specify what you want<a class=headerlink href=#specify-what-you-want title="Permanent link">&para;</a></h3> <p>The base-syntax for <code>getopts</code> is:</p> <div class=highlight><pre><span></span><code>getopts OPTSTRING VARNAME [ARGS...]
</code></pre></div> <p>where:</p> <table> <thead> <tr> <th>Option</th> <th>Description</th> </tr> </thead> <tbody> <tr> <td><code>OPTSTRING</code></td> <td>tells <code>getopts</code> which options to expect and where to expect arguments (see below)</td> </tr> <tr> <td><code>VARNAME</code></td> <td>tells <code>getopts</code> which shell-variable to use for option reporting</td> </tr> <tr> <td><code>ARGS</code></td> <td>tells <code>getopts</code> to parse these optional words instead of the positional parameters</td> </tr> </tbody> </table> <h4 id=the-option-string>The option-string<a class=headerlink href=#the-option-string title="Permanent link">&para;</a></h4> <p>The option-string tells <code>getopts</code> which options to expect and which of them must have an argument. The syntax is very simple --- every option character is simply named as is, this example-string would tell <code>getopts</code> to look for <code>-f</code>, <code>-A</code> and <code>-x</code>:</p> <div class=highlight><pre><span></span><code>getopts fAx VARNAME
</code></pre></div> <p>When you want <code>getopts</code> to expect an argument for an option, just place a <code>:</code> (colon) after the proper option flag. If you want <code>-A</code> to expect an argument (i.e. to become <code>-A SOMETHING</code>) just do:</p> <div class=highlight><pre><span></span><code>getopts fA:x VARNAME
</code></pre></div> <p>If the <strong>very first character</strong> of the option-string is a <code>:</code> (colon), which would normally be nonsense because there's no option letter preceding it, <code>getopts</code> switches to "<strong>silent error reporting mode</strong>". In productive scripts, this is usually what you want because it allows you to handle errors yourself without being disturbed by annoying messages.</p> <h4 id=custom-arguments-to-parse>Custom arguments to parse<a class=headerlink href=#custom-arguments-to-parse title="Permanent link">&para;</a></h4> <p>The <code>getopts</code> utility parses the <a href=../../scripting/posparams/ >positional parameters</a> of the current shell or function by default (which means it parses <code>"$@"</code>).</p> <p>You can give your own set of arguments to the utility to parse. Whenever additional arguments are given after the <code>VARNAME</code> parameter, <code>getopts</code> doesn't try to parse the positional parameters, but these given words.</p> <p>This way, you are able to parse any option set you like, here for example from an array:</p> <div class=highlight><pre><span></span><code>while getopts :f:h opt &quot;${MY_OWN_SET[@]}&quot;; do
...
done
</code></pre></div> <p>A call to <code>getopts</code> <strong>without</strong> these additional arguments is <strong>equivalent</strong> to explicitly calling it with <code>"$@"</code>:</p> <div class=highlight><pre><span></span><code>getopts ... &quot;$@&quot;
</code></pre></div> <h3 id=error-reporting>Error Reporting<a class=headerlink href=#error-reporting title="Permanent link">&para;</a></h3> <p>Regarding error-reporting, there are two modes <code>getopts</code> can run in:</p> <ul> <li>verbose mode</li> <li>silent mode</li> </ul> <p>For productive scripts I recommend to use the silent mode, since everything looks more professional, when you don't see annoying standard messages. Also it's easier to handle, since the failure cases are indicated in an easier way.</p> <h4 id=verbose-mode>Verbose Mode<a class=headerlink href=#verbose-mode title="Permanent link">&para;</a></h4> <table> <thead> <tr> <th>failure</th> <th>message</th> </tr> </thead> <tbody> <tr> <td>invalid option</td> <td><code>VARNAME</code> is set to <code>?</code> (question-mark) and <code>OPTARG</code> is unset</td> </tr> <tr> <td>required argument not found</td> <td><code>VARNAME</code> is set to <code>?</code> (question-mark), <code>OPTARG</code> is unset and an <em>error message is printed</em></td> </tr> </tbody> </table> <h4 id=silent-mode>Silent Mode<a class=headerlink href=#silent-mode title="Permanent link">&para;</a></h4> <table> <thead> <tr> <th>failure</th> <th>message</th> </tr> </thead> <tbody> <tr> <td>invalid option</td> <td><code>VARNAME</code> is set to <code>?</code> (question-mark) and <code>OPTARG</code> is set to the (invalid) option character</td> </tr> <tr> <td>required argument not found</td> <td><code>VARNAME</code> is set to <code>:</code> (colon) and <code>OPTARG</code> contains the option-character in question</td> </tr> </tbody> </table> <h2 id=using-it>Using it<a class=headerlink href=#using-it title="Permanent link">&para;</a></h2> <h3 id=a-first-example>A first example<a class=headerlink href=#a-first-example title="Permanent link">&para;</a></h3> <p>Enough said - action!</p> <p>Let's play with a very simple case: only one option (<code>-a</code>) expected, without any arguments. Also we disable the <em>verbose error handling</em> by preceding the whole option string with a colon (<code>:</code>):</p> <div class=highlight><pre><span></span><code><a id=__codelineno-0-1 name=__codelineno-0-1 href=#__codelineno-0-1></a><span class=ch>#!/bin/bash</span>
<a id=__codelineno-0-2 name=__codelineno-0-2 href=#__codelineno-0-2></a>
<a id=__codelineno-0-3 name=__codelineno-0-3 href=#__codelineno-0-3></a><span class=k>while</span><span class=w> </span><span class=nb>getopts</span><span class=w> </span><span class=s2>&quot;:a&quot;</span><span class=w> </span>opt<span class=p>;</span><span class=w> </span><span class=k>do</span>
<a id=__codelineno-0-4 name=__codelineno-0-4 href=#__codelineno-0-4></a><span class=w> </span><span class=k>case</span><span class=w> </span><span class=nv>$opt</span><span class=w> </span><span class=k>in</span>
<a id=__codelineno-0-5 name=__codelineno-0-5 href=#__codelineno-0-5></a><span class=w> </span>a<span class=o>)</span>
<a id=__codelineno-0-6 name=__codelineno-0-6 href=#__codelineno-0-6></a><span class=w> </span><span class=nb>echo</span><span class=w> </span><span class=s2>&quot;-a was triggered!&quot;</span><span class=w> </span>&gt;<span class=p>&amp;</span><span class=m>2</span>
<a id=__codelineno-0-7 name=__codelineno-0-7 href=#__codelineno-0-7></a><span class=w> </span><span class=p>;;</span>
<a id=__codelineno-0-8 name=__codelineno-0-8 href=#__codelineno-0-8></a><span class=w> </span><span class=se>\?</span><span class=o>)</span>
<a id=__codelineno-0-9 name=__codelineno-0-9 href=#__codelineno-0-9></a><span class=w> </span><span class=nb>echo</span><span class=w> </span><span class=s2>&quot;Invalid option: -</span><span class=nv>$OPTARG</span><span class=s2>&quot;</span><span class=w> </span>&gt;<span class=p>&amp;</span><span class=m>2</span>
<a id=__codelineno-0-10 name=__codelineno-0-10 href=#__codelineno-0-10></a><span class=w> </span><span class=p>;;</span>
<a id=__codelineno-0-11 name=__codelineno-0-11 href=#__codelineno-0-11></a><span class=w> </span><span class=k>esac</span>
<a id=__codelineno-0-12 name=__codelineno-0-12 href=#__codelineno-0-12></a><span class=k>done</span>
</code></pre></div> <p>I put that into a file named <code>go_test.sh</code>, which is the name you'll see below in the examples.</p> <p>Let's do some tests:</p> <h4 id=calling-it-without-any-arguments>Calling it without any arguments<a class=headerlink href=#calling-it-without-any-arguments title="Permanent link">&para;</a></h4> <div class=highlight><pre><span></span><code>$ ./go_test.sh
$
</code></pre></div> <p>Nothing happened? Right. <code>getopts</code> didn't see any valid or invalid options (letters preceded by a dash), so it wasn't triggered.</p> <h4 id=calling-it-with-non-option-arguments>Calling it with non-option arguments<a class=headerlink href=#calling-it-with-non-option-arguments title="Permanent link">&para;</a></h4> <div class=highlight><pre><span></span><code>$ ./go_test.sh /etc/passwd
$
</code></pre></div> <p>Again --- nothing happened. The <strong>very same</strong> case: <code>getopts</code> didn't see any valid or invalid options (letters preceded by a dash), so it wasn't triggered.</p> <p>The arguments given to your script are of course accessible as <code>$1</code> - <code>${N}</code>.</p> <h4 id=calling-it-with-option-arguments>Calling it with option-arguments<a class=headerlink href=#calling-it-with-option-arguments title="Permanent link">&para;</a></h4> <p>Now let's trigger <code>getopts</code>: Provide options.</p> <p>First, an <strong>invalid</strong> one:</p> <div class=highlight><pre><span></span><code>$ ./go_test.sh -b
Invalid option: -b
$
</code></pre></div> <p>As expected, <code>getopts</code> didn't accept this option and acted like told above: It placed <code>?</code> into <code>$opt</code> and the invalid option character (<code>b</code>) into <code>$OPTARG</code>. With our <code>case</code> statement, we were able to detect this.</p> <p>Now, a <strong>valid</strong> one (<code>-a</code>):</p> <div class=highlight><pre><span></span><code>$ ./go_test.sh -a
-a was triggered!
$
</code></pre></div> <p>You see, the detection works perfectly. The <code>a</code> was put into the variable <code>$opt</code> for our case statement.</p> <p>Of course it's possible to <strong>mix valid and invalid</strong> options when calling:</p> <div class=highlight><pre><span></span><code>$ ./go_test.sh -a -x -b -c
-a was triggered!
Invalid option: -x
Invalid option: -b
Invalid option: -c
$
</code></pre></div> <p>Finally, it's of course possible, to give our option <strong>multiple times</strong>:</p> <div class=highlight><pre><span></span><code>$ ./go_test.sh -a -a -a -a
-a was triggered!
-a was triggered!
-a was triggered!
-a was triggered!
$
</code></pre></div> <p>The last examples lead us to some points you may consider:</p> <ul> <li><strong>invalid options don't stop the processing</strong>: If you want to stop the script, you have to do it yourself (<code>exit</code> in the right place)</li> <li><strong>multiple identical options are possible</strong>: If you want to disallow these, you have to check manually (e.g. by setting a variable or so)</li> </ul> <h3 id=an-option-with-argument>An option with argument<a class=headerlink href=#an-option-with-argument title="Permanent link">&para;</a></h3> <p>Let's extend our example from above. Just a little bit:</p> <ul> <li><code>-a</code> now takes an argument</li> <li>on an error, the parsing exits with <code>exit 1</code></li> </ul> <div class=highlight><pre><span></span><code><a id=__codelineno-1-1 name=__codelineno-1-1 href=#__codelineno-1-1></a><span class=ch>#!/bin/bash</span>
<a id=__codelineno-1-2 name=__codelineno-1-2 href=#__codelineno-1-2></a>
<a id=__codelineno-1-3 name=__codelineno-1-3 href=#__codelineno-1-3></a><span class=k>while</span><span class=w> </span><span class=nb>getopts</span><span class=w> </span><span class=s2>&quot;:a:&quot;</span><span class=w> </span>opt<span class=p>;</span><span class=w> </span><span class=k>do</span>
<a id=__codelineno-1-4 name=__codelineno-1-4 href=#__codelineno-1-4></a><span class=w> </span><span class=k>case</span><span class=w> </span><span class=nv>$opt</span><span class=w> </span><span class=k>in</span>
<a id=__codelineno-1-5 name=__codelineno-1-5 href=#__codelineno-1-5></a><span class=w> </span>a<span class=o>)</span>
<a id=__codelineno-1-6 name=__codelineno-1-6 href=#__codelineno-1-6></a><span class=w> </span><span class=nb>echo</span><span class=w> </span><span class=s2>&quot;-a was triggered, Parameter: </span><span class=nv>$OPTARG</span><span class=s2>&quot;</span><span class=w> </span>&gt;<span class=p>&amp;</span><span class=m>2</span>
<a id=__codelineno-1-7 name=__codelineno-1-7 href=#__codelineno-1-7></a><span class=w> </span><span class=p>;;</span>
<a id=__codelineno-1-8 name=__codelineno-1-8 href=#__codelineno-1-8></a><span class=w> </span><span class=se>\?</span><span class=o>)</span>
<a id=__codelineno-1-9 name=__codelineno-1-9 href=#__codelineno-1-9></a><span class=w> </span><span class=nb>echo</span><span class=w> </span><span class=s2>&quot;Invalid option: -</span><span class=nv>$OPTARG</span><span class=s2>&quot;</span><span class=w> </span>&gt;<span class=p>&amp;</span><span class=m>2</span>
<a id=__codelineno-1-10 name=__codelineno-1-10 href=#__codelineno-1-10></a><span class=w> </span><span class=nb>exit</span><span class=w> </span><span class=m>1</span>
<a id=__codelineno-1-11 name=__codelineno-1-11 href=#__codelineno-1-11></a><span class=w> </span><span class=p>;;</span>
<a id=__codelineno-1-12 name=__codelineno-1-12 href=#__codelineno-1-12></a><span class=w> </span>:<span class=o>)</span>
<a id=__codelineno-1-13 name=__codelineno-1-13 href=#__codelineno-1-13></a><span class=w> </span><span class=nb>echo</span><span class=w> </span><span class=s2>&quot;Option -</span><span class=nv>$OPTARG</span><span class=s2> requires an argument.&quot;</span><span class=w> </span>&gt;<span class=p>&amp;</span><span class=m>2</span>
<a id=__codelineno-1-14 name=__codelineno-1-14 href=#__codelineno-1-14></a><span class=w> </span><span class=nb>exit</span><span class=w> </span><span class=m>1</span>
<a id=__codelineno-1-15 name=__codelineno-1-15 href=#__codelineno-1-15></a><span class=w> </span><span class=p>;;</span>
<a id=__codelineno-1-16 name=__codelineno-1-16 href=#__codelineno-1-16></a><span class=w> </span><span class=k>esac</span>
<a id=__codelineno-1-17 name=__codelineno-1-17 href=#__codelineno-1-17></a><span class=k>done</span>
</code></pre></div> <p>Let's do the very same tests we did in the last example:</p> <h4 id=calling-it-without-any-arguments_1>Calling it without any arguments<a class=headerlink href=#calling-it-without-any-arguments_1 title="Permanent link">&para;</a></h4> <div class=highlight><pre><span></span><code>$ ./go_test.sh
$
</code></pre></div> <p>As above, nothing happened. It wasn't triggered.</p> <h4 id=calling-it-with-non-option-arguments_1>Calling it with non-option arguments<a class=headerlink href=#calling-it-with-non-option-arguments_1 title="Permanent link">&para;</a></h4> <div class=highlight><pre><span></span><code>$ ./go_test.sh /etc/passwd
$
</code></pre></div> <p>The <strong>very same</strong> case: It wasn't triggered.</p> <h4 id=calling-it-with-option-arguments_1>Calling it with option-arguments<a class=headerlink href=#calling-it-with-option-arguments_1 title="Permanent link">&para;</a></h4> <p><strong>Invalid</strong> option:</p> <div class=highlight><pre><span></span><code>$ ./go_test.sh -b
Invalid option: -b
$
</code></pre></div> <p>As expected, as above, <code>getopts</code> didn't accept this option and acted like programmed.</p> <p><strong>Valid</strong> option, but without the mandatory <strong>argument</strong>:</p> <div class=highlight><pre><span></span><code>$ ./go_test.sh -a
Option -a requires an argument.
$
</code></pre></div> <p>The option was okay, but there is an argument missing.</p> <p>Let's provide <strong>the argument</strong>:</p> <div class=highlight><pre><span></span><code>$ ./go_test.sh -a /etc/passwd
-a was triggered, Parameter: /etc/passwd
$
</code></pre></div> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">&para;</a></h2> <ul> <li>Internal: <a href=../../scripting/posparams/ >posparams</a></li> <li>Internal: <a href=../../syntax/ccmd/case/ >case</a></li> <li>Internal: <a href=../../syntax/ccmd/while_loop/ >while_loop</a></li> <li>POSIX <a href=http://pubs.opengroup.org/onlinepubs/9699919799/utilities/getopts.html#tag_20_54>getopts(1)</a> and <a href=http://pubs.opengroup.org/onlinepubs/9699919799/functions/getopt.html>getopt(3)</a></li> <li><a href=https://stackoverflow.com/questions/192249/how-do-i-parse-command-line-arguments-in-bash>parse CLI ARGV</a></li> <li><a href=http://mywiki.wooledge.org/BashFAQ/035>handle command-line arguments (options) to a script</a></li> </ul> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date">November 13, 2024</span> </span> <span class=md-source-file__fact> <span class=md-icon title=Created> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M14.47 15.08 11 13V7h1.5v5.25l3.08 1.83c-.41.28-.79.62-1.11 1m-1.39 4.84c-.36.05-.71.08-1.08.08-4.42 0-8-3.58-8-8s3.58-8 8-8 8 3.58 8 8c0 .37-.03.72-.08 1.08.69.1 1.33.32 1.92.64.1-.56.16-1.13.16-1.72 0-5.5-4.5-10-10-10S2 6.5 2 12s4.47 10 10 10c.59 0 1.16-.06 1.72-.16-.32-.59-.54-1.23-.64-1.92M18 15v3h-3v2h3v3h2v-3h3v-2h-3v-3z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date">November 13, 2024</span> </span> </aside> <h2 id=__comments>Comments</h2> <script src=https://giscus.app/client.js data-repo=flokoe/bash-hackers-wiki data-repo-id=R_kgDOJ3Nr6Q data-category="Giscus Page Comments" data-category-id=DIC_kwDOJ3Nr6c4CXq9t data-mapping=pathname data-strict=1 data-reactions-enabled=1 data-emit-metadata=0 data-input-position=top data-theme=preferred_color_scheme data-lang=en data-loading=lazy crossorigin=anonymous async>
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