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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/scripting/bashchanges/ rel=canonical><link href=../bashbehaviour/ rel=prev><link href=../basics/ rel=next><link rel=icon href=../../assets/images/favicon.png><meta name=generator content="mkdocs-1.6.1, mkdocs-material-9.5.44"><title>Bash changes - 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 URL("../..",location),__md_hash=e=>[...e].reduce(((e,_)=>(e<<5)-e+_.charCodeAt(0)),0),__md_get=(e,_=localStorage,t=__md_scope)=>JSON.parse(_.getItem(t.pathname+"."+e)),__md_set=(e,_,t=localStorage,a=__md_scope)=>{try{t.setItem(a.pathname+"."+e,JSON.stringify(_))}catch(e){}}</script></head> <body dir=ltr data-md-color-scheme=default data-md-color-primary=indigo data-md-color-accent=indigo> <input class=md-toggle data-md-toggle=drawer type=checkbox id=__drawer autocomplete=off> <input class=md-toggle data-md-toggle=search type=checkbox id=__search autocomplete=off> <label class=md-overlay for=__drawer></label> <div data-md-component=skip> <a href=#bash-changes class=md-skip> Skip to content </a> </div> <div data-md-component=announce> </div> <header class=md-header data-md-component=header> <nav class="md-header__inner md-grid" aria-label=Header> <a href=../.. title="The Bash Hackers Wiki" class="md-header__button md-logo" aria-label="The Bash Hackers Wiki" data-md-component=logo> <svg 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12.1C428.2 457.8 496 362.9 496 252 496 113.3 383.5 8 244.8 8M97.2 352.9c-1.3 1-1 3.3.7 5.2 1.6 1.6 3.9 2.3 5.2 1 1.3-1 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> </nav> </header> <div class=md-container data-md-component=container> <nav class=md-tabs aria-label=Tabs data-md-component=tabs> <div class=md-grid> <ul class=md-tabs__list> <li class=md-tabs__item> <a href=../.. class=md-tabs__link> Start </a> </li> <li class=md-tabs__item> <a href=../../commands/classictest/ class=md-tabs__link> Commands </a> </li> <li class=md-tabs__item> <a href=../../dict/directory/ class=md-tabs__link> Dict </a> </li> <li class=md-tabs__item> <a href=../../howto/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 md-tabs__item--active"> <a href=../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 md-nav--primary md-nav--lifted" aria-label=Navigation 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5.2-3.6 3-.3 5.6 1.3 5.6 3.6m-31.1-4.5c-.7 2 1.3 4.3 4.3 4.9 2.6 1 5.6 0 6.2-2s-1.3-4.3-4.3-5.2c-2.6-.7-5.5.3-6.2 2.3m44.2-1.7c-2.9.7-4.9 2.6-4.6 4.9.3 2 2.9 3.3 5.9 2.6 2.9-.7 4.9-2.6 4.6-4.6-.3-1.9-3-3.2-5.9-2.9M244.8 8C106.1 8 0 113.3 0 252c0 110.9 69.8 205.8 169.5 239.2 12.8 2.3 17.3-5.6 17.3-12.1 0-6.2-.3-40.4-.3-61.4 0 0-70 15-84.7-29.8 0 0-11.4-29.1-27.8-36.6 0 0-22.9-15.7 1.6-15.4 0 0 24.9 2 38.6 25.8 21.9 38.6 58.6 27.5 72.9 20.9 2.3-16 8.8-27.1 16-33.7-55.9-6.2-112.3-14.3-112.3-110.5 0-27.5 7.6-41.3 23.6-58.9-2.6-6.5-11.1-33.3 2.6-67.9 20.9-6.5 69 27 69 27 20-5.6 41.5-8.5 62.8-8.5s42.8 2.9 62.8 8.5c0 0 48.1-33.6 69-27 13.7 34.7 5.2 61.4 2.6 67.9 16 17.7 25.8 31.5 25.8 58.9 0 96.5-58.9 104.2-114.8 110.5 9.2 7.9 17 22.9 17 46.4 0 33.7-.3 75.4-.3 83.6 0 6.5 4.6 14.4 17.3 12.1C428.2 457.8 496 362.9 496 252 496 113.3 383.5 8 244.8 8M97.2 352.9c-1.3 1-1 3.3.7 5.2 1.6 1.6 3.9 2.3 5.2 1 1.3-1 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--nested"> <input class="md-nav__toggle md-toggle " type=checkbox id=__nav_4> <label class=md-nav__link for=__nav_4 id=__nav_4_label tabindex=0> <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=false> <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=../../howto/calculate-dc/ class=md-nav__link> <span class=md-ellipsis> Calculating with dc </span> </a> </li> <li class=md-nav__item> <a href=../../howto/collapsing_functions/ class=md-nav__link> <span class=md-ellipsis> Collapsing Functions </span> </a> </li> <li class=md-nav__item> <a href=../../howto/conffile/ class=md-nav__link> <span class=md-ellipsis> Config files for your script </span> </a> </li> <li class=md-nav__item> <a href=../../howto/dissectabadoneliner/ class=md-nav__link> <span class=md-ellipsis> Dissect a bad oneliner </span> </a> </li> <li class=md-nav__item> <a href=../../howto/edit-ed/ class=md-nav__link> <span class=md-ellipsis> Editing files via scripts with ed </span> </a> </li> <li class=md-nav__item> <a href=../../howto/getopts_tutorial/ class=md-nav__link> <span class=md-ellipsis> Small getopts tutorial </span> </a> </li> <li class=md-nav__item> <a href=../../howto/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=../../howto/pax/ class=md-nav__link> <span class=md-ellipsis> pax - the POSIX archiver </span> </a> </li> <li class=md-nav__item> <a href=../../howto/redirection_tutorial/ class=md-nav__link> <span class=md-ellipsis> Illustrated Redirection Tutorial </span> </a> </li> <li class=md-nav__item> <a href=../../howto/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--active md-nav__item--section md-nav__item--nested"> <input class="md-nav__toggle md-toggle " type=checkbox id=__nav_7 checked> <label class=md-nav__link for=__nav_7 id=__nav_7_label tabindex> <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=true> <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=../bashbehaviour/ class=md-nav__link> <span class=md-ellipsis> Bash's behaviour </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> Bash changes </span> <span class="md-nav__icon md-icon"></span> </label> <a href=./ class="md-nav__link md-nav__link--active"> <span class=md-ellipsis> Bash changes </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=#shell-options class=md-nav__link> <span class=md-ellipsis> Shell options </span> </a> <nav class=md-nav aria-label="Shell options"> <ul class=md-nav__list> <li class=md-nav__item> <a href=#general-allmany-builtins class=md-nav__link> <span class=md-ellipsis> General (all/many builtins) </span> </a> </li> <li class=md-nav__item> <a href=#printf class=md-nav__link> <span class=md-ellipsis> printf </span> </a> </li> <li class=md-nav__item> <a href=#conditional-expressions-and-test-command class=md-nav__link> <span class=md-ellipsis> Conditional expressions and test command </span> </a> </li> <li class=md-nav__item> <a href=#other-builtins-and-keywords class=md-nav__link> <span class=md-ellipsis> Other builtins and keywords </span> </a> </li> </ul> </nav> </li> <li class=md-nav__item> <a href=#builtin-variables class=md-nav__link> <span class=md-ellipsis> Builtin variables </span> </a> </li> <li class=md-nav__item> <a href=#quoting-expansions-substitutions-and-related class=md-nav__link> <span class=md-ellipsis> Quoting, expansions, substitutions and related </span> </a> </li> <li class=md-nav__item> <a href=#arithmetic class=md-nav__link> <span class=md-ellipsis> Arithmetic </span> </a> </li> <li class=md-nav__item> <a href=#redirection-and-related class=md-nav__link> <span class=md-ellipsis> Redirection and related </span> </a> </li> <li class=md-nav__item> <a href=#misc class=md-nav__link> <span class=md-ellipsis> Misc </span> </a> </li> </ul> </nav> </li> <li class=md-nav__item> <a href=../basics/ class=md-nav__link> <span class=md-ellipsis> The basics of shell scripting </span> </a> </li> <li class=md-nav__item> <a href=../debuggingtips/ class=md-nav__link> <span class=md-ellipsis> Debugging a script </span> </a> </li> <li class=md-nav__item> <a href=../newbie_traps/ class=md-nav__link> <span class=md-ellipsis> Beginner Mistakes </span> </a> </li> <li class=md-nav__item> <a href=../nonportable/ class=md-nav__link> <span class=md-ellipsis> Portability talk </span> </a> </li> <li class=md-nav__item> <a href=../obsolete/ class=md-nav__link> <span class=md-ellipsis> Obsolete and deprecated syntax </span> </a> </li> <li class=md-nav__item> <a href=../posparams/ class=md-nav__link> <span class=md-ellipsis> Handling positional parameters </span> </a> </li> <li class=md-nav__item> <a href=../processtree/ class=md-nav__link> <span class=md-ellipsis> Bash and the process tree </span> </a> </li> <li class=md-nav__item> <a href=../style/ class=md-nav__link> <span class=md-ellipsis> Scripting with style </span> </a> </li> <li class=md-nav__item> <a href=../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=#shell-options class=md-nav__link> <span class=md-ellipsis> Shell options </span> </a> <nav class=md-nav aria-label="Shell options"> <ul class=md-nav__list> <li class=md-nav__item> <a href=#general-allmany-builtins class=md-nav__link> <span class=md-ellipsis> General (all/many builtins) </span> </a> </li> <li class=md-nav__item> <a href=#printf class=md-nav__link> <span class=md-ellipsis> printf </span> </a> </li> <li class=md-nav__item> <a href=#conditional-expressions-and-test-command class=md-nav__link> <span class=md-ellipsis> Conditional expressions and test command </span> </a> </li> <li class=md-nav__item> <a href=#other-builtins-and-keywords class=md-nav__link> <span class=md-ellipsis> Other builtins and keywords </span> </a> </li> </ul> </nav> </li> <li class=md-nav__item> <a href=#builtin-variables class=md-nav__link> <span class=md-ellipsis> Builtin variables </span> </a> </li> <li class=md-nav__item> <a href=#quoting-expansions-substitutions-and-related class=md-nav__link> <span class=md-ellipsis> Quoting, expansions, substitutions and related </span> </a> </li> <li class=md-nav__item> <a href=#arithmetic class=md-nav__link> <span class=md-ellipsis> Arithmetic </span> </a> </li> <li class=md-nav__item> <a href=#redirection-and-related class=md-nav__link> <span class=md-ellipsis> Redirection and related </span> </a> </li> <li class=md-nav__item> <a href=#misc class=md-nav__link> <span class=md-ellipsis> Misc </span> </a> </li> </ul> </nav> </div> </div> </div> <div class=md-content data-md-component=content> <article class="md-content__inner md-typeset"> <a href=https://github.com/flokoe/bash-hackers-wiki/edit/main/docs/scripting/bashchanges.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/scripting/bashchanges.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=bash-changes>Bash changes<a class=headerlink href=#bash-changes title="Permanent link">&para;</a></h1> <p>This article is an <strong>incomplete overview</strong> of changes to Bash over time. Not all changes are listed, just the ones most likely to be useful for normal scripting. The overviews are categorized by topic and ordered by version.</p> <p>A useful starting point is the <a href=https://github.com/bminor/bash/blob/master/NEWS>NEWS file</a> in bash sources. If you have more detailed information, or historical information about Bash versions earlier than V2, feel free to mail me, or use the discussion below.</p> <p>Status: 5.1 (alpha)</p> <h2 id=shell-options>Shell options<a class=headerlink href=#shell-options title="Permanent link">&para;</a></h2> <p>Note that the <code>shopt</code> builtin command first appeared in Bash 2.0.</p> <p>For this topic, see also</p> <ul> <li><a href=../../internals/shell_options/ >shell_options</a></li> <li><a href=../../commands/builtin/set/ >set</a></li> </ul> <table> <thead> <tr> <th>Feature or change description</th> <th>Appeared in Bash version</th> <th>See also/remarks</th> </tr> </thead> <tbody> <tr> <td><code>posix</code> (for <code>set -o</code>)</td> <td>1.14.0</td> <td></td> </tr> <tr> <td><code>hostcomplete</code></td> <td>2.0-alpha3</td> <td></td> </tr> <tr> <td><code>expand_aliases</code></td> <td>2.0</td> <td></td> </tr> <tr> <td><code>huponexit</code></td> <td>2.02-alpha1</td> <td></td> </tr> <tr> <td><code>nocaseglob</code></td> <td>2.02-alpha1</td> <td></td> </tr> <tr> <td><code>extglob</code></td> <td>2.02-alpha1</td> <td>together with extended globbing, KSH88</td> </tr> <tr> <td><code>restricted_shell</code></td> <td>2.03-alpha</td> <td></td> </tr> <tr> <td><code>xpg_echo</code></td> <td>2.04-beta1</td> <td></td> </tr> <tr> <td><code>progcomp</code></td> <td>2.04-alpha1</td> <td></td> </tr> <tr> <td><code>no_empty_command_completion</code></td> <td>2.04</td> <td></td> </tr> <tr> <td><code>login_shell</code></td> <td>2.05a-alpha1</td> <td></td> </tr> <tr> <td><code>nolog</code> (for <code>set -o</code>)</td> <td>2.05a</td> <td></td> </tr> <tr> <td><code>gnu_errfmt</code></td> <td>3.0-alpha</td> <td></td> </tr> <tr> <td><code>force_fignore</code></td> <td>3.0-alpha</td> <td></td> </tr> <tr> <td><code>failglob</code></td> <td>3.0-alpha</td> <td></td> </tr> <tr> <td><code>extquote</code></td> <td>3.0-alpha</td> <td>unsure -- verify!</td> </tr> <tr> <td><code>extdebug</code></td> <td>3.0-alpha</td> <td></td> </tr> <tr> <td><code>pipefail</code> (for <code>set -o</code>)</td> <td>3.0</td> <td></td> </tr> <tr> <td><code>functrace</code> (for <code>set -o</code>)</td> <td>3.0</td> <td></td> </tr> <tr> <td><code>errtrace</code> (for <code>set -o</code>)</td> <td>3.0</td> <td></td> </tr> <tr> <td><code>nocasematch</code></td> <td>3.1-alpha1</td> <td></td> </tr> <tr> <td><code>dirspell</code></td> <td>4.0-alpha</td> <td></td> </tr> <tr> <td><code>globstar</code></td> <td>4.0-alpha</td> <td></td> </tr> <tr> <td><code>checkjobs</code></td> <td>4.0-alpha</td> <td></td> </tr> <tr> <td><code>autocd</code></td> <td>4.0-alpha</td> <td></td> </tr> <tr> <td><code>set -e</code> effects more intuitive</td> <td>4.0</td> <td>not directly specified by POSIX, but in consensus with POSIX WG</td> </tr> <tr> <td><code>compat40</code></td> <td>4.1-beta</td> <td></td> </tr> <tr> <td><code>lastpipe</code></td> <td>4.2-alpha</td> <td>only works with job control disabled</td> </tr> <tr> <td><code>compat41</code></td> <td>4.2-alpha</td> <td></td> </tr> <tr> <td><code>globasciiranges</code></td> <td>4.3-alpha</td> <td>enable "character range globbing" to always act as if in <code>C</code> locale</td> </tr> <tr> <td><code>compat42</code></td> <td>4.3-alpha</td> <td></td> </tr> <tr> <td><code>compat43</code></td> <td>4.4-alpha</td> <td></td> </tr> <tr> <td><code>compat44</code></td> <td>5.0-alpha</td> <td></td> </tr> <tr> <td><code>localvar_inherit</code></td> <td>5.0-alpha</td> <td>local variables inherit preceeding scope values if they have the same name</td> </tr> <tr> <td><code>syslog_history</code></td> <td>5.0-alpha</td> <td>send history lines to syslog (undocumented, default off) if syslog is supported</td> </tr> <tr> <td><code>assoc_expand_once</code></td> <td>5.0-alpha</td> <td>expand associative array subscripts only one</td> </tr> <tr> <td><code>globasciiranges</code></td> <td>5.0-beta</td> <td>New default: on (default may be configured at compile time)</td> </tr> <tr> <td><code>localvar_inherit</code></td> <td>5.0-beta</td> <td>guard code against inheriting from an incompatible data type</td> </tr> <tr> <td><code>checkwinsize</code></td> <td>5.0-beta2</td> <td>New default: on</td> </tr> <tr> <td><code>shift_verbose</code></td> <td>5.0-beta2</td> <td>Default on when in POSIX mode</td> </tr> </tbody> </table> <h3 id=general-allmany-builtins>General (all/many builtins)<a class=headerlink href=#general-allmany-builtins title="Permanent link">&para;</a></h3> <table> <thead> <tr> <th>Feature or change description</th> <th>Appeared in Bash version</th> <th>See also/remarks</th> </tr> </thead> <tbody> <tr> <td>generally return 2 on usage error</td> <td>2.0</td> <td></td> </tr> <tr> <td>generally accept <code>--</code> (end of options)</td> <td>2.0</td> <td></td> </tr> <tr> <td>(where applicable) implement a <code>-p</code> option to produce reusable output</td> <td>2.0</td> <td><code>shopt</code> and <code>umask</code> builtins were fixed to support that in 2.02</td> </tr> </tbody> </table> <h3 id=printf>printf<a class=headerlink href=#printf title="Permanent link">&para;</a></h3> <p>For this topic, see also</p> <ul> <li><a href=../../commands/builtin/printf/ >printf</a></li> </ul> <table> <thead> <tr> <th>Feature or change description</th> <th>Appeared in Bash version</th> <th>See also/remarks</th> </tr> </thead> <tbody> <tr> <td>new <code>printf</code> command</td> <td>2.02-alpha1</td> <td></td> </tr> <tr> <td>respects <code>0..</code> and <code>0x..</code> prefixed numbers</td> <td>2.04-beta1</td> <td>consistency with arithmetic</td> </tr> <tr> <td>POSIX&reg; length specifiers <code>j</code>, <code>t</code> and <code>z</code></td> <td>2.05a-alpha1</td> <td>ISO C99</td> </tr> <tr> <td>POSIX&reg; flag <code>'</code></td> <td>2.05a-alpha1</td> <td></td> </tr> <tr> <td>conversion <code>a</code> and <code>A</code></td> <td>2.05a-rc1</td> <td>if provided by the underlying printf(3)</td> </tr> <tr> <td>conversion <code>F</code></td> <td>2.05a-rc1</td> <td></td> </tr> <tr> <td>conversion <code>n</code></td> <td>2.05a-rc1</td> <td></td> </tr> <tr> <td>new option <code>-v</code></td> <td>3.1-alpha1</td> <td></td> </tr> <tr> <td>escape sequences <code>\"</code> and <code>\?</code></td> <td>3.0-beta1</td> <td></td> </tr> <tr> <td>modified option <code>-v</code> to assign to individual array elements</td> <td>4.1-alpha</td> <td></td> </tr> <tr> <td>conversion <code>(...)T</code></td> <td>4.2-alpha</td> <td>support stftime(3) date/time format; uses current time</td> </tr> <tr> <td><code>\uNNNN</code> and <code>\UNNNNNNNN</code> escape sequences</td> <td>4.2-alpha</td> <td>for: <code>printf</code>, <code>echo -e</code>, <code>$'...'</code></td> </tr> </tbody> </table> <h3 id=conditional-expressions-and-test-command>Conditional expressions and test command<a class=headerlink href=#conditional-expressions-and-test-command title="Permanent link">&para;</a></h3> <p>For this topic, see also</p> <ul> <li><a href=../../syntax/ccmd/conditional_expression/ >conditional_expression</a></li> <li><a href=../../commands/classictest/ >classictest</a></li> </ul> <table> <thead> <tr> <th>Feature or change description</th> <th>Appeared in Bash version</th> <th>See also/remarks</th> </tr> </thead> <tbody> <tr> <td><code>test</code>: <code>-o</code>, <code>==</code>, <code>&lt;</code> and <code>&gt;</code></td> <td>2.0</td> <td></td> </tr> <tr> <td><code>test</code>: <code>-N</code></td> <td>2.02</td> <td></td> </tr> <tr> <td><code>[[...]]</code>: new</td> <td>2.02-alpha1</td> <td>KSH93</td> </tr> <tr> <td><code>[[...]]</code>: regex support (<code>=~</code>)</td> <td>3.0-alpha</td> <td></td> </tr> <tr> <td><code>[[...]]</code>: quotable right-hand-side of <code>=~</code> forces string matching</td> <td>3.2-alpha</td> <td>for consistency with pattern matching</td> </tr> <tr> <td><code>[[...]]</code>: <code>&lt;</code> and <code>&gt;</code> operators respect locale</td> <td>4.1-alpha</td> <td>for consistency, since 4.1-beta: ensure you have set compatiblity to &gt;4.0 (default)</td> </tr> <tr> <td><code>test</code>/<code>[</code>/<code>[[</code>: <code>-v</code></td> <td>4.2-alpha</td> <td>check if a variable is set</td> </tr> <tr> <td><code>test</code>/<code>[</code>/<code>[[</code>: <code>-v</code></td> <td>4.2-alpha</td> <td>support array syntax to check for elements</td> </tr> <tr> <td><code>test</code>/<code>[</code>/<code>[[</code>: <code>-N</code> accepts nanoseconds</td> <td>5.1-alpha</td> <td></td> </tr> <tr> <td><code>test</code>/<code>[</code>/<code>[[</code>: <code>-v</code> accepts positional parameters</td> <td>5.1-alpha</td> <td></td> </tr> </tbody> </table> <h3 id=other-builtins-and-keywords>Other builtins and keywords<a class=headerlink href=#other-builtins-and-keywords title="Permanent link">&para;</a></h3> <table> <thead> <tr> <th>Builtin</th> <th>Feature or change description</th> <th>Appeared in Bash version</th> <th>See also/remarks</th> </tr> </thead> <tbody> <tr> <td><code>bashbug</code></td> <td>new</td> <td>1.14.0</td> <td></td> </tr> <tr> <td><code>select</code></td> <td>new</td> <td>1.14.0</td> <td></td> </tr> <tr> <td><code>disown</code></td> <td>new</td> <td>2.0</td> <td></td> </tr> <tr> <td><code>shopt</code></td> <td>new</td> <td>2.0</td> <td><a href=../../commands/builtin/shopt/ >shopt</a></td> </tr> <tr> <td><code>declare</code></td> <td>new options <code>-a</code> and <code>-F</code></td> <td>2.0</td> <td></td> </tr> <tr> <td><code>enable</code></td> <td>builtin has basic plugin support (dlopen)</td> <td>2.0</td> <td></td> </tr> <tr> <td><code>exec</code></td> <td>options <code>-l</code>, <code>-c</code> and <code>-a</code></td> <td>2.0</td> <td></td> </tr> <tr> <td><code>read</code></td> <td>options <code>-p</code>, <code>-e</code> and <code>-a</code></td> <td>2.0</td> <td><a href=../../commands/builtin/read/ >read</a></td> </tr> <tr> <td><code>readonly</code></td> <td>option <code>-a</code></td> <td>2.0</td> <td><a href=../../syntax/arrays/ >arrays</a></td> </tr> <tr> <td><code>time</code></td> <td>new keyword</td> <td>2.0</td> <td></td> </tr> <tr> <td><code>shopt</code></td> <td><code>-p</code> (reusable output)</td> <td>2.02</td> <td></td> </tr> <tr> <td><code>umask</code></td> <td><code>-p</code> (reusable output)</td> <td>2.02</td> <td></td> </tr> <tr> <td><code>complete</code></td> <td>new</td> <td>2.04-devel</td> <td>for and together with support for programmable completion</td> </tr> <tr> <td><code>compgen</code></td> <td>new</td> <td>2.04-devel</td> <td>for and together with support for programmable completion</td> </tr> <tr> <td><code>read</code></td> <td>options <code>-t</code>, <code>-n</code>, <code>-d</code>, <code>-s</code></td> <td>2.04-devel</td> <td><a href=../../commands/builtin/read/ >read</a></td> </tr> <tr> <td><code>for ((...;...;...))</code></td> <td>new</td> <td>2.04-devel</td> <td>KSH93</td> </tr> <tr> <td><code>set</code></td> <td>print shell functions in a format reusable as input</td> <td>2.05-beta1</td> <td></td> </tr> <tr> <td><code>for</code></td> <td>allow an empty word list</td> <td>2.05a-alpha1</td> <td></td> </tr> <tr> <td><code>read</code></td> <td>new option <code>-u</code></td> <td>2.05b-alpha1</td> <td><a href=../../commands/builtin/read/ >read</a></td> </tr> <tr> <td><code>caller</code></td> <td>new</td> <td>3.0</td> <td><a href=../../commands/builtin/caller/ >caller</a></td> </tr> <tr> <td><code>coproc</code></td> <td>new</td> <td>4.0-alpha</td> <td></td> </tr> <tr> <td><code>declare</code></td> <td>new options <code>-l</code> and <code>-u</code></td> <td>4.0-alpha</td> <td>together with case-changing expansion forms</td> </tr> <tr> <td><code>case</code></td> <td>new action list terminators '';;&amp; and '';&amp;</td> <td>4.0-alpha</td> <td>ksh93: only <code>;&amp;</code>. zsh and mksh: <code>;|</code>. mksh: all 4, (<code>;;&amp;</code> is undocumented Bash compatibility)</td> </tr> <tr> <td><code>read</code></td> <td>changed <code>-t</code> (fractional seconds)</td> <td>4.0-alpha</td> <td></td> </tr> <tr> <td><code>mapfile</code></td> <td>new</td> <td>4.0-alpha</td> <td></td> </tr> <tr> <td><code>read</code></td> <td>new option <code>-i</code></td> <td>4.0-alpha</td> <td></td> </tr> <tr> <td><code>compopt</code></td> <td>new</td> <td>4.0-alpha</td> <td></td> </tr> <tr> <td><code>read</code></td> <td>modified option <code>-t</code> to test for data</td> <td>4.0-beta</td> <td></td> </tr> <tr> <td><code>read</code></td> <td>new option <code>-N</code></td> <td>4.1-alpha</td> <td></td> </tr> <tr> <td><code>mapfile</code></td> <td>changed behaviour regarding history spamming</td> <td>4.1-alpha</td> <td></td> </tr> <tr> <td><code>declare</code></td> <td>new option <code>-g</code></td> <td>4.2-alpha</td> <td></td> </tr> <tr> <td><code>mapfile</code></td> <td>calls the callback with an additional argument: The line (data)</td> <td>4.2-alpha</td> <td></td> </tr> <tr> <td><code>cd</code></td> <td>new option <code>-e</code></td> <td>4.2-alpha</td> <td></td> </tr> <tr> <td><code>echo</code></td> <td><code>\uNNNN</code> and <code>\UNNNNNNNN</code> escape sequences</td> <td>4.2-alpha</td> <td>for: <code>printf</code>, <code>echo -e</code>, <code>$'...'</code></td> </tr> <tr> <td><code>exec</code></td> <td>option <code>-a</code> to give a <code>argv[0]</code> string</td> <td>4.2-alpha</td> <td></td> </tr> <tr> <td><code>time</code></td> <td>allowed as a command by itself to display timing values of the shell and its children</td> <td>4.2-alpha</td> <td>POSIX change</td> </tr> <tr> <td><code>help</code></td> <td><code>help</code> now searches exact topic-strings (i.e. <code>help read</code> won't find <code>readonly</code> anymore)</td> <td>4.3-alpha</td> <td></td> </tr> <tr> <td><code>return</code></td> <td>accept negative values as return value (e.g. <code>return -1</code> will show as (8 bit) 255 in the caller)</td> <td>4.3-alpha</td> <td></td> </tr> <tr> <td><code>exit</code></td> <td>accept negative values as return value (e.g. <code>return -1</code> will show as (8 bit) 255 in the caller)</td> <td>4.3-alpha</td> <td></td> </tr> <tr> <td><code>read</code></td> <td><code>read</code> skips <code>NUL</code> (ASCII Code 0) in input</td> <td>4.3-alpha</td> <td></td> </tr> <tr> <td><code>declare</code></td> <td>new option <code>-n</code>/<code>+n</code> to support nameref variable type</td> <td>4.3-alpha</td> <td></td> </tr> <tr> <td><code>wait</code></td> <td>new option <code>-n</code> to wait for the next background job to finish, returning its exit status.</td> <td>4.3-alpha</td> <td></td> </tr> <tr> <td><code>read</code></td> <td><code>read</code> checks first variable argument for validity before trying to read inout</td> <td>4.3-beta</td> <td></td> </tr> <tr> <td><code>help</code></td> <td>attempts substring matching (as it did through bash-4.2) if exact string matching fails</td> <td>4.3-beta2</td> <td></td> </tr> <tr> <td><code>fc</code></td> <td>interprets option <code>-0</code> (zero) as the current command line</td> <td>4.3-beta2</td> <td></td> </tr> <tr> <td><code>cd</code></td> <td>new option <code>-@</code> to browse a file's extended attributes (on systems that support <code>O_XATTR</code>)</td> <td>4.3-rc1</td> <td></td> </tr> <tr> <td><code>kill</code></td> <td>new option <code>-L</code> (upper case ell) to list signals like the normal lowercase option <code>-l</code> (compatiblity with some standalone <code>kill</code> commands)</td> <td>4.4-beta</td> <td></td> </tr> <tr> <td><code>mapfile</code></td> <td>new option <code>-d</code></td> <td>4.4-alpha</td> <td></td> </tr> <tr> <td><code>wait</code></td> <td>new option <code>-f</code></td> <td>5.0-alpha</td> <td></td> </tr> <tr> <td><code>history</code></td> <td>option <code>-d</code> allows negative numbers to index from the end of the history list</td> <td>5.0-alpha</td> <td></td> </tr> <tr> <td><code>umask</code></td> <td>allows modes greater than octal 777</td> <td>5.0-alpha</td> <td></td> </tr> <tr> <td><code>times</code></td> <td>honors current locale settings when printing decimal points</td> <td>5.0-alpha</td> <td></td> </tr> <tr> <td><code>kill</code></td> <td>New options <code>-n SIGNUMBER</code> and <code>-s SIGNAME</code></td> <td>5.0-beta2</td> <td><a href=/commands/builtin/kill>kill</a></td> </tr> <tr> <td><code>select</code></td> <td>Support for an empty wordlist following <code>in</code></td> <td>5.0-beta2</td> <td></td> </tr> <tr> <td><code>read</code></td> <td>Option <code>-e</code> (use ReadLine to obtain input) now works with arbitrary file descriptors (given by <code>-u</code> option)</td> <td>5.1-alpha</td> <td></td> </tr> <tr> <td><code>trap</code></td> <td><code>-p</code> option prints signals with SIG_DFL/SIG_IGN on shell start (POSIX mode)</td> <td>5.1-alpha</td> <td></td> </tr> <tr> <td><code>unset</code></td> <td>automatically tries to unset a function if the given name is an invalid variable name</td> <td>5.1-aplha</td> <td></td> </tr> <tr> <td><code>wait</code></td> <td>option <code>-n</code> now accepts a list of jobs</td> <td>5.1-alpha</td> <td></td> </tr> <tr> <td><code>wait</code></td> <td>new option <code>-p NAME</code> to store PID/JobID (useful when waiting for a list of jobs)</td> <td>5.1-alpha</td> <td></td> </tr> <tr> <td><code>local</code></td> <td>new option <code>-p</code> to print local variables in the current scope</td> <td>5.1-alpha</td> <td></td> </tr> <tr> <td><code>ulimit</code></td> <td>new option <code>-R</code> to get/set <code>RLIMIT_RTTIME</code> resource</td> <td>5.1-alpha</td> <td></td> </tr> </tbody> </table> <h2 id=builtin-variables>Builtin variables<a class=headerlink href=#builtin-variables title="Permanent link">&para;</a></h2> <table> <thead> <tr> <th>Feature or change description</th> <th>Appeared in Bash version</th> <th>See also</th> </tr> </thead> <tbody> <tr> <td><code>HISTCMD</code></td> <td>1.14.0</td> <td>interactive usage</td> </tr> <tr> <td><code>PS1</code>, <code>PS2</code>, <code>PATH</code>, and <code>IFS</code> are unsettable</td> <td>2.0</td> <td></td> </tr> <tr> <td><code>DIRSTACK</code> array variable</td> <td>2.0</td> <td></td> </tr> <tr> <td><code>PIPESTATUS</code> array variable</td> <td>2.0</td> <td></td> </tr> <tr> <td><code>BASH_VERSINFO</code> array variable</td> <td>2.0</td> <td></td> </tr> <tr> <td><code>HOSTNAME</code></td> <td>2.0</td> <td></td> </tr> <tr> <td><code>SHELLOPTS</code></td> <td>2.0</td> <td></td> </tr> <tr> <td><code>MACHTYPE</code></td> <td>2.0</td> <td></td> </tr> <tr> <td><code>GLOBIGNORE</code></td> <td>2.0</td> <td></td> </tr> <tr> <td><code>HISTIGNORE</code></td> <td>2.0</td> <td></td> </tr> <tr> <td>respect <code>LC_ALL</code></td> <td>2.0</td> <td></td> </tr> <tr> <td>respect <code>LC_MESSAGES</code></td> <td>2.0</td> <td></td> </tr> <tr> <td>respect <code>LC_CTYPE</code></td> <td>2.0</td> <td></td> </tr> <tr> <td>respect <code>LC_COLLATE</code></td> <td>2.0</td> <td></td> </tr> <tr> <td>respect <code>LANG</code></td> <td>2.0</td> <td></td> </tr> <tr> <td><code>GROUPS</code> array variable</td> <td>2.01</td> <td></td> </tr> <tr> <td><code>GROUPS</code> unsettable/takes (discarded) assignments</td> <td>2.04</td> <td></td> </tr> <tr> <td><code>FUNCNAME</code></td> <td>2.04</td> <td></td> </tr> <tr> <td>respect <code>LC_NUMERIC</code></td> <td>2.04</td> <td></td> </tr> <tr> <td><code>TMOUT</code></td> <td>2.05b</td> <td></td> </tr> <tr> <td><code>BASH_REMATCH</code></td> <td>3.0</td> <td>together with regex support in <code>[[...]]</code></td> </tr> <tr> <td><code>BASH_ARGC</code></td> <td>3.0</td> <td>debugger support</td> </tr> <tr> <td><code>BASH_ARGV</code></td> <td>3.0</td> <td>debugger support</td> </tr> <tr> <td><code>BASH_SOURCE</code></td> <td>3.0</td> <td>debugger support</td> </tr> <tr> <td><code>BASH_LINENO</code></td> <td>3.0</td> <td>debugger support</td> </tr> <tr> <td><code>BASH_SUBSHELL</code></td> <td>3.0</td> <td>debugger support</td> </tr> <tr> <td><code>BASH_EXECUTION_STRING</code></td> <td>3.0</td> <td>debugger support</td> </tr> <tr> <td><code>BASH_COMMAND</code></td> <td>3.0</td> <td>debugger support</td> </tr> <tr> <td><code>HISTTIMEFORMAT</code></td> <td>3.0</td> <td></td> </tr> <tr> <td><code>COMP_WORDBREAKS</code></td> <td>3.0</td> <td></td> </tr> <tr> <td>respect <code>LC_TIME</code></td> <td>3.1</td> <td></td> </tr> <tr> <td><code>BASHPID</code></td> <td>4.0-alpha</td> <td>Added to mksh R41.</td> </tr> <tr> <td><code>PROMPT_DIRTRIM</code></td> <td>4.0</td> <td></td> </tr> <tr> <td><code>BASH_XTRACEFD</code></td> <td>4.1-alpha</td> <td></td> </tr> <tr> <td><code>BASHOPTS</code></td> <td>4.1-alpha</td> <td></td> </tr> <tr> <td><code>FUNCNEST</code></td> <td>4.2-alpha</td> <td></td> </tr> <tr> <td><code>HISTSIZE</code></td> <td>4.3-alpha</td> <td>can be set to negative values for unlimited history length</td> </tr> <tr> <td><code>HISTFILESIZE</code></td> <td>4.3-alpha</td> <td>can be set to negative values for unlimit history file size</td> </tr> <tr> <td><code>CHILD_MAX</code></td> <td>4.3-alpha</td> <td>max. number of exit status of children the shell remembers</td> </tr> <tr> <td><code>BASH_COMPAT</code></td> <td>4.3-alpha</td> <td>set shell compatiblity levels</td> </tr> <tr> <td><code>EPOCHSECONDS</code></td> <td>5.0-alpha</td> <td>expands to the time in seconds since Unix epoch</td> </tr> <tr> <td><code>EPOCHREALTIME</code></td> <td>5.0-alpha</td> <td>expands to the time in seconds since Unix epoch with microsecond granularity</td> </tr> <tr> <td><code>BASH_ARGV0</code></td> <td>5.0-alpha</td> <td>get/set <code>$0</code></td> </tr> <tr> <td><code>PATH</code></td> <td>5.0-alpha</td> <td>Possibility to set a static path for use in a restricted shell (at compile time)</td> </tr> <tr> <td><code>HISTSIZE</code></td> <td>5.0-beta</td> <td>Default can now be set at runtime</td> </tr> <tr> <td><code>SRANDOM</code></td> <td>5.1-alpha</td> <td>New random generator for 32bit numbers (using various methods in the backend)</td> </tr> <tr> <td><code>ARGV0</code></td> <td>5.1-alpha</td> <td>Respected when set in initial shell environment, then initially used to set <code>$0</code></td> </tr> <tr> <td><code>BASH_REMATCH</code></td> <td>5.1-alpha</td> <td>Not readonly anymore</td> </tr> <tr> <td><code>PROMPT_COMMANDS</code></td> <td>5.1-alpha</td> <td>New array variable. List of commands to be executed like <code>PROMPT_COMMAND</code></td> </tr> <tr> <td><code>SECONDS</code></td> <td>5.1-alpha</td> <td>Assignment using arithmetic expressions (is nominally an integer variabnle)</td> </tr> <tr> <td><code>RANDOM</code></td> <td>5.1-alpha</td> <td>Assignment using arithmetic expressions (is nominally an integer variabnle)</td> </tr> <tr> <td><code>LINENO</code></td> <td>5.1-alpha</td> <td>Not an integer variabe</td> </tr> </tbody> </table> <h2 id=quoting-expansions-substitutions-and-related>Quoting, expansions, substitutions and related<a class=headerlink href=#quoting-expansions-substitutions-and-related title="Permanent link">&para;</a></h2> <p>For this topic, see also</p> <ul> <li><a href=../../syntax/pe/ >pe</a>.</li> </ul> <table> <thead> <tr> <th>Feature or change description</th> <th>Appeared in Bash version</th> <th>Remarks</th> </tr> </thead> <tbody> <tr> <td>Support for integer-indexed arrays</td> <td>2.0</td> <td>relevant builtins also got array support</td> </tr> <tr> <td><code>${PARAMETER//PATTERN/REPLACEMENT}</code></td> <td>2.0</td> <td></td> </tr> <tr> <td><code>${PARAMETER:OFFSET:LENGTH}</code></td> <td>2.0</td> <td></td> </tr> <tr> <td><code>${!PARAMETER}</code> (indirection)</td> <td>2.0</td> <td></td> </tr> <tr> <td><code>$"..."</code> (localized strings)</td> <td>2.0</td> <td></td> </tr> <tr> <td><code>$'...'</code> (ANSI-C-like strings)</td> <td>2.0</td> <td></td> </tr> <tr> <td><code>\xNNN</code> in <code>$'...'</code> (and <code>echo -e</code>)</td> <td>2.02-alpha1</td> <td></td> </tr> <tr> <td><code>$(&lt; FILENAME)</code> (file content)</td> <td>2.02-alpha1</td> <td></td> </tr> <tr> <td>globbing (<code>fnmatch()</code>) capable of POSIX&reg; character classes etc.</td> <td>2.02-alpha1</td> <td></td> </tr> <tr> <td>extended globbing</td> <td>2.02-alpha1</td> <td>KSH88</td> </tr> <tr> <td>globbing inside array mass-assignment: <code>ARRAY=(*.txt)</code></td> <td>2.03-alpha</td> <td></td> </tr> <tr> <td><code>$'...\'...'</code> escaped single quote inside ANSI-C-like strings</td> <td>2.04-devel</td> <td>KSH93</td> </tr> <tr> <td><code>${!PREFIX*}</code> (parameter name expansion)</td> <td>2.04</td> <td>KSH93</td> </tr> <tr> <td><code>$'...'</code> expands <code>\cx</code> (Control-x)</td> <td>2.05b</td> <td></td> </tr> <tr> <td><code>[:class:]</code> syntax for pattern matching</td> <td>2.05b</td> <td>KSH93</td> </tr> <tr> <td><code>${!ARRAY[@]}</code> (array index expansion)</td> <td>3.0-alpha</td> <td>KSH93</td> </tr> <tr> <td><code>{x..y}</code> (range brace expansion)</td> <td>3.0-alpha</td> <td></td> </tr> <tr> <td><code>$'...'</code> expands <code>\xNNN</code> (Hexdigits)</td> <td>3.0</td> <td></td> </tr> <tr> <td><code>+=</code> operator for arrays and strings</td> <td>3.1-alpha1</td> <td></td> </tr> <tr> <td><code>${PARAMETER//PATTERN/REPLACEMENT}</code> behaviour changed</td> <td>3.2-alpha</td> <td>anchoring for global substitution is no longer allowed, changes the way old syntax may work</td> </tr> <tr> <td><code>${@:0:x}</code> includes <code>$0</code></td> <td>4.0-alpha</td> <td></td> </tr> <tr> <td>Support for associative arrays</td> <td>4.0-alpha</td> <td>relevant builtins also got associative array support</td> </tr> <tr> <td>case modification operators for expansions</td> <td>4.0-alpha</td> <td></td> </tr> <tr> <td><code>{0x..0y}</code> (zeropadding brace expansion)</td> <td>4.0-alpha</td> <td></td> </tr> <tr> <td>numerically indexed arrays can be accessed (on expansion time) from the end using negative indexes</td> <td>4.1-alpha</td> <td></td> </tr> <tr> <td><code>\uNNNN</code> and <code>\uNNNNNNNN</code> in <code>$'...'</code></td> <td>4.2-alpha</td> <td>for: <code>printf</code>, <code>echo -e</code>, <code>$'...'</code></td> </tr> <tr> <td><code>${PARAMETER:OFFSET:LENGTH}</code>: Negative <code>LENGTH</code> values are used as offset from the end of the string</td> <td>4.2-alpha</td> <td>Substrings only for Bash and ksh93. Works also for argument expansions in zsh. ksh93 can use <code>${arr[n..-m]}</code>.</td> </tr> <tr> <td>Word expansions like <code>${foo##bar}</code> understand indirect variable references</td> <td>4.3-beta</td> <td></td> </tr> <tr> <td>Transformations</td> <td>4.4</td> <td></td> </tr> <tr> <td>Process substitution now works in POSIX mode</td> <td>5.1-alpha</td> <td></td> </tr> <tr> <td>New transformations: <code>U</code>, <code>u</code>, <code>L</code></td> <td>5.1-alpha</td> <td>Case-transformation</td> </tr> <tr> <td>New transformation: <code>K</code></td> <td>5.1-alpha</td> <td>Display associative arrays as key/value pairs</td> </tr> </tbody> </table> <h2 id=arithmetic>Arithmetic<a class=headerlink href=#arithmetic title="Permanent link">&para;</a></h2> <p>For this topic, see also</p> <ul> <li><a href=../../syntax/arith_expr/ >arith_expr</a></li> <li><a href=../../syntax/expansion/arith/ >arith</a></li> </ul> <table> <thead> <tr> <th>Feature or change description</th> <th>Appeared in Bash version</th> <th>Remarks</th> </tr> </thead> <tbody> <tr> <td><code>((...))</code></td> <td>2.0-beta2</td> <td>KSH93</td> </tr> <tr> <td>ternary operator</td> <td>2.0</td> <td></td> </tr> <tr> <td>base 64 integer constants</td> <td>2.0</td> <td>the max. base before is unknown. Anybody?</td> </tr> <tr> <td>deprecated <code>$[...]</code> in favor of <code>$((...))</code></td> <td>2.0</td> <td></td> </tr> <tr> <td>exponentiaition operator (<code>**</code>)</td> <td>2.02-alpha1</td> <td></td> </tr> <tr> <td>comma operator <code>EXPR,EXPR</code></td> <td>2.04-devel</td> <td></td> </tr> <tr> <td>pre- and postfix operators</td> <td>2.04-devel</td> <td></td> </tr> </tbody> </table> <h2 id=redirection-and-related>Redirection and related<a class=headerlink href=#redirection-and-related title="Permanent link">&para;</a></h2> <p>For this topic, see also</p> <ul> <li><a href=../../syntax/redirection/ >redirection</a></li> </ul> <table> <thead> <tr> <th>Feature or change description</th> <th>Appeared in Bash version</th> <th>Remarks</th> </tr> </thead> <tbody> <tr> <td>socket redirection (<code>/dev/tcp/</code>, <code>/dev/udp/</code>)</td> <td>2.04-devel</td> <td></td> </tr> <tr> <td>OS/filesystem-independent support for <code>/dev/std(in|out|err)</code> and <code>/dev/fd/*</code></td> <td>2.04</td> <td></td> </tr> <tr> <td>socket redirection accepts service names</td> <td>2.05</td> <td></td> </tr> <tr> <td><code>[n]&lt;&amp;word-</code> and <code>[n]&gt;&amp;word-</code> FD-duplicate/closing</td> <td>2.05b-alpha1</td> <td>KSH93</td> </tr> <tr> <td>Here strings: <code>&lt;&lt;&lt; WORD</code></td> <td>2.05b-alpha1</td> <td></td> </tr> <tr> <td><code>|&amp;</code> (synonym for <code>2&gt;&amp;1|</code>)</td> <td>4.0-alpha</td> <td></td> </tr> <tr> <td><code>&amp;&gt;&gt;</code> (equiv. to <code>&gt;&gt;FILE 2&gt;&amp;1</code>)</td> <td>4.0-alpha</td> <td></td> </tr> <tr> <td><code>{varname}</code> style automatic file descriptor allocation</td> <td>4.1-alpha</td> <td>ksh93</td> </tr> <tr> <td><code>{varname[idx]}</code> fd allocation accepts array subscripts and special-meaning variables</td> <td>4.3-alpha</td> <td>ksh93</td> </tr> </tbody> </table> <h2 id=misc>Misc<a class=headerlink href=#misc title="Permanent link">&para;</a></h2> <table> <thead> <tr> <th>Feature or change description</th> <th>Appeared in Bash version</th> <th>See also/remarks</th> </tr> </thead> <tbody> <tr> <td><code>DEBUG</code> trap</td> <td>2.0</td> <td></td> </tr> <tr> <td><code>ERR</code> trap</td> <td>2.05a</td> <td>KSH93</td> </tr> <tr> <td>Support for multibyte characters: Unicode / UTF8</td> <td>2.05b</td> <td></td> </tr> <tr> <td><code>RETURN</code> trap</td> <td>3.0</td> <td>ksh93 <code>EXIT</code> trap evaluates in caller scope (for <code>function name {</code>). Bash <code>RETURN</code> in same scope.</td> </tr> <tr> <td><code>command_not_found_handle</code> handler function</td> <td>4.0-alpha</td> <td></td> </tr> <tr> <td>official introduction of switchable "compatiblity levels"</td> <td>4.0-alpha</td> <td><code>compat31</code> was introduced in a 3.2 version, mainly because of the incompatibilities that were introduced by the changed <code>=~</code> operator</td> </tr> <tr> <td><code>[[...]]</code> and <code>((...))</code> conditional commands are subject to the <code>ERR</code> trap and <code>set -e</code> feature</td> <td>4.1-alpha</td> <td></td> </tr> <tr> <td>ACL support for file status checks</td> <td>4.1-alpha</td> <td></td> </tr> <tr> <td>Assignment to negative array indices</td> <td>4.3-alpha</td> <td>ksh93, zsh</td> </tr> <tr> <td><code>declare</code>/<code>typeset -n</code></td> <td>4.3-alpha</td> <td>Support for nameref variable type, a variable referencing another one by name</td> </tr> <tr> <td>shells started to run process substitutions now run any trap set on <code>EXIT</code></td> <td>4.3-beta</td> <td></td> </tr> <tr> <td>process substitution does not inherit the <code>v</code> flag</td> <td>5.0-alpha</td> <td></td> </tr> <tr> <td><code>ERR</code> trap</td> <td>5.0-alpha</td> <td>Reports more reliable line numbers</td> </tr> <tr> <td>Variable assignment</td> <td>5.0-beta</td> <td>Assignments preceeding a special builtin that chages variable attributes are not propagated back unless compatiblity mode is 44 or lower</td> </tr> </tbody> </table> <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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