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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> <a href=../bashchanges/ class=md-nav__link> <span class=md-ellipsis> Bash changes </span> </a> </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 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> Handling positional parameters </span> <span class="md-nav__icon md-icon"></span> </label> <a href=./ class="md-nav__link md-nav__link--active"> <span class=md-ellipsis> Handling positional parameters </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=#intro class=md-nav__link> <span class=md-ellipsis> Intro </span> </a> </li> <li class=md-nav__item> <a href=#the-first-argument class=md-nav__link> <span class=md-ellipsis> The first argument </span> </a> </li> <li class=md-nav__item> <a href=#shifting class=md-nav__link> <span class=md-ellipsis> Shifting </span> </a> </li> <li class=md-nav__item> <a href=#using-them class=md-nav__link> <span class=md-ellipsis> Using them </span> </a> <nav class=md-nav aria-label="Using them"> <ul class=md-nav__list> <li class=md-nav__item> <a href=#one-by-one class=md-nav__link> <span class=md-ellipsis> One by one </span> </a> </li> <li class=md-nav__item> <a href=#loops class=md-nav__link> <span class=md-ellipsis> Loops </span> </a> </li> <li class=md-nav__item> <a href=#getopts class=md-nav__link> <span class=md-ellipsis> Getopts </span> </a> </li> </ul> </nav> </li> <li class=md-nav__item> <a href=#mass-usage class=md-nav__link> <span class=md-ellipsis> Mass usage </span> </a> <nav class=md-nav aria-label="Mass usage"> <ul class=md-nav__list> <li class=md-nav__item> <a href=#all-positional-parameters class=md-nav__link> <span class=md-ellipsis> All Positional Parameters </span> </a> </li> <li class=md-nav__item> <a href=#range-of-positional-parameters class=md-nav__link> <span class=md-ellipsis> Range Of Positional Parameters </span> </a> </li> </ul> </nav> </li> <li class=md-nav__item> <a href=#setting-positional-parameters class=md-nav__link> <span class=md-ellipsis> Setting Positional Parameters </span> </a> </li> <li class=md-nav__item> <a href=#production-examples class=md-nav__link> <span class=md-ellipsis> Production examples </span> </a> <nav class=md-nav aria-label="Production examples"> <ul class=md-nav__list> <li class=md-nav__item> <a href=#using-a-while-loop class=md-nav__link> <span class=md-ellipsis> Using a while loop </span> </a> </li> <li class=md-nav__item> <a href=#filter-unwanted-options-with-a-wrapper-script class=md-nav__link> <span class=md-ellipsis> Filter unwanted options with a wrapper script </span> </a> </li> <li class=md-nav__item> <a href=#using-getopts class=md-nav__link> <span class=md-ellipsis> Using getopts </span> </a> </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=../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=#intro class=md-nav__link> <span class=md-ellipsis> Intro </span> </a> </li> <li class=md-nav__item> <a href=#the-first-argument class=md-nav__link> <span class=md-ellipsis> The first argument </span> </a> </li> <li class=md-nav__item> <a href=#shifting class=md-nav__link> <span class=md-ellipsis> Shifting </span> </a> </li> <li class=md-nav__item> <a href=#using-them class=md-nav__link> <span class=md-ellipsis> Using them </span> </a> <nav class=md-nav aria-label="Using them"> <ul class=md-nav__list> <li class=md-nav__item> <a href=#one-by-one class=md-nav__link> <span class=md-ellipsis> One by one </span> </a> </li> <li class=md-nav__item> <a href=#loops class=md-nav__link> <span class=md-ellipsis> Loops </span> </a> </li> <li class=md-nav__item> <a href=#getopts class=md-nav__link> <span class=md-ellipsis> Getopts </span> </a> </li> </ul> </nav> </li> <li class=md-nav__item> <a href=#mass-usage class=md-nav__link> <span class=md-ellipsis> Mass usage </span> </a> <nav class=md-nav aria-label="Mass usage"> <ul class=md-nav__list> <li class=md-nav__item> <a href=#all-positional-parameters class=md-nav__link> <span class=md-ellipsis> All Positional Parameters </span> </a> </li> <li class=md-nav__item> <a href=#range-of-positional-parameters class=md-nav__link> <span class=md-ellipsis> Range Of Positional Parameters </span> </a> </li> </ul> </nav> </li> <li class=md-nav__item> <a href=#setting-positional-parameters class=md-nav__link> <span class=md-ellipsis> Setting Positional Parameters </span> </a> </li> <li class=md-nav__item> <a href=#production-examples class=md-nav__link> <span class=md-ellipsis> Production examples </span> </a> <nav class=md-nav aria-label="Production examples"> <ul class=md-nav__list> <li class=md-nav__item> <a href=#using-a-while-loop class=md-nav__link> <span class=md-ellipsis> Using a while loop </span> </a> </li> <li class=md-nav__item> <a href=#filter-unwanted-options-with-a-wrapper-script class=md-nav__link> <span class=md-ellipsis> Filter unwanted options with a wrapper script </span> </a> </li> <li class=md-nav__item> <a href=#using-getopts class=md-nav__link> <span class=md-ellipsis> Using getopts </span> </a> </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> </nav> <a href=https://github.com/flokoe/bash-hackers-wiki/edit/main/docs/scripting/posparams.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/posparams.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=handling-positional-parameters>Handling positional parameters<a class=headerlink href=#handling-positional-parameters title="Permanent link">¶</a></h1> <h2 id=intro>Intro<a class=headerlink href=#intro title="Permanent link">¶</a></h2> <p>The day will come when you want to give arguments to your scripts. These arguments are known as <strong>positional parameters</strong>. Some relevant special parameters are described below:</p> <table> <thead> <tr> <th>Parameter(s)</th> <th>Description</th> </tr> </thead> <tbody> <tr> <td><code>$0</code></td> <td>the first positional parameter, equivalent to <code>argv[0]</code> in C, see <a href=./#the_first_argument>the first argument</a></td> </tr> <tr> <td><code>$FUNCNAME</code></td> <td>the function name (<u><strong>attention</strong></u>: inside a function, <code>$0</code> is still the <code>$0</code> of the shell, <strong>not</strong> the function name)</td> </tr> <tr> <td><code>$1 ... $9</code></td> <td>the argument list elements from 1 to 9</td> </tr> <tr> <td><code>${10} ... ${N}</code></td> <td>the argument list elements beyond 9 (note the <a href=../../syntax/pe/ >parameter expansion</a> syntax!)</td> </tr> <tr> <td><code>$*</code></td> <td>all positional parameters except <code>$0</code>, see <a href=./#mass_usage>mass usage</a></td> </tr> <tr> <td><code>$@</code></td> <td>all positional parameters except <code>$0</code>, see <a href=./#mass_usage>mass usage</a></td> </tr> <tr> <td><code>$#</code></td> <td>the number of arguments, not counting <code>$0</code></td> </tr> </tbody> </table> <p>These positional parameters reflect exactly what was given to the script when it was called.</p> <p>Option-switch parsing (e.g. <code>-h</code> for displaying help) is not performed at this point.</p> <p>See also <a href=../../dict/parameter/ >the dictionary entry for "parameter"</a>.</p> <h2 id=the-first-argument>The first argument<a class=headerlink href=#the-first-argument title="Permanent link">¶</a></h2> <p>The very first argument you can access is referenced as <code>$0</code>. It is usually set to the script's name exactly as called, and it's set on shell initialization:</p> <p><u>Testscript</u> - it just echos <code>$0</code>:</p> <div class=highlight><pre><span></span><code>#!/bin/bash
|
|
echo "$0"
|
|
</code></pre></div> <p>You see, <code>$0</code> is always set to the name the script is called with (<code>></code> is the prompt...):</p> <div class=highlight><pre><span></span><code>> ./testscript
|
|
./testscript
|
|
|
|
> /usr/bin/testscript
|
|
/usr/bin/testscript
|
|
</code></pre></div> <p>However, this isn't true for login shells:</p> <div class=highlight><pre><span></span><code>> echo "$0"
|
|
-bash
|
|
</code></pre></div> <p>In other terms, <code>$0</code> is not a positional parameter, it's a special parameter independent from the positional parameter list. It can be set to anything. In the <strong>ideal</strong> case it's the pathname of the script, but since this gets set on invocation, the invoking program can easily influence it (the <code>login</code> program does that for login shells, by prefixing a dash, for example).</p> <p>Inside a function, <code>$0</code> still behaves as described above. To get the function name, use <code>$FUNCNAME</code>.</p> <h2 id=shifting>Shifting<a class=headerlink href=#shifting title="Permanent link">¶</a></h2> <p>The builtin command <code>shift</code> is used to change the positional parameter values:</p> <ul> <li><code>$1</code> will be discarded</li> <li><code>$2</code> will become <code>$1</code></li> <li><code>$3</code> will become <code>$2</code></li> <li>...</li> <li>in general: <code>$N</code> will become <code>$N-1</code></li> </ul> <p>The command can take a number as argument: Number of positions to shift. e.g. <code>shift 4</code> shifts <code>$5</code> to <code>$1</code>.</p> <h2 id=using-them>Using them<a class=headerlink href=#using-them title="Permanent link">¶</a></h2> <p>Enough theory, you want to access your script-arguments. Well, here we go.</p> <h3 id=one-by-one>One by one<a class=headerlink href=#one-by-one title="Permanent link">¶</a></h3> <p>One way is to access specific parameters:</p> <div class=highlight><pre><span></span><code>#!/bin/bash
|
|
echo "Total number of arguments: $#"
|
|
echo "Argument 1: $1"
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|
echo "Argument 2: $2"
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echo "Argument 3: $3"
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echo "Argument 4: $4"
|
|
echo "Argument 5: $5"
|
|
</code></pre></div> <p>While useful in another situation, this way is lacks flexibility. The maximum number of arguments is a fixedvalue - which is a bad idea if you write a script that takes many filenames as arguments.</p> <p>=> forget that one</p> <h3 id=loops>Loops<a class=headerlink href=#loops title="Permanent link">¶</a></h3> <p>There are several ways to loop through the positional parameters.</p> <hr> <p>You can code a <a href=../../syntax/ccmd/c_for/ >C-style for-loop</a> using <code>$#</code> as the end value. On every iteration, the <code>shift</code>-command is used to shift the argument list:</p> <div class=highlight><pre><span></span><code>numargs=$#
|
|
for ((i=1 ; i <= numargs ; i++))
|
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do
|
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echo "$1"
|
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shift
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done
|
|
</code></pre></div> <p>Not very stylish, but usable. The <code>numargs</code> variable is used to store the initial value of <code>$#</code> because the shift command will change it as the script runs.</p> <hr> <p>Another way to iterate one argument at a time is the <code>for</code> loop without a given wordlist. The loop uses the positional parameters as a wordlist:</p> <div class=highlight><pre><span></span><code>for arg
|
|
do
|
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echo "$arg"
|
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done
|
|
</code></pre></div> <p><u>Advantage:</u> The positional parameters will be preserved</p> <hr> <p>The next method is similar to the first example (the <code>for</code> loop), but it doesn't test for reaching <code>$#</code>. It shifts and checks if <code>$1</code> still expands to something, using the <a href=../../commands/classictest/ >test command</a>:</p> <div class=highlight><pre><span></span><code>while [ "$1" ]
|
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do
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echo "$1"
|
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shift
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done
|
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</code></pre></div> <p>Looks nice, but has the disadvantage of stopping when <code>$1</code> is empty (null-string). Let's modify it to run as long as <code>$1</code> is defined (but may be null), using <a href=../../syntax/pe/#use_an_alternate_value>parameter expansion for an alternate value</a>:</p> <div class=highlight><pre><span></span><code>while [ "${1+defined}" ]; do
|
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echo "$1"
|
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shift
|
|
done
|
|
</code></pre></div> <h3 id=getopts>Getopts<a class=headerlink href=#getopts title="Permanent link">¶</a></h3> <p>There is a <a href=../../howto/getopts_tutorial/ >small tutorial dedicated to <code>getopts</code></a> (<em>under construction</em>).</p> <h2 id=mass-usage>Mass usage<a class=headerlink href=#mass-usage title="Permanent link">¶</a></h2> <h3 id=all-positional-parameters>All Positional Parameters<a class=headerlink href=#all-positional-parameters title="Permanent link">¶</a></h3> <p>Sometimes it's necessary to just "relay" or "pass" given arguments to another program. It's very inefficient to do that in one of these loops, as you will destroy integrity, most likely (spaces!).</p> <p>The shell developers created <code>$*</code> and <code>$@</code> for this purpose.</p> <p>As overview:</p> <table> <thead> <tr> <th>Syntax</th> <th>Effective result</th> </tr> </thead> <tbody> <tr> <td><code>$*</code></td> <td><code>$1 $2 $3 ... ${N}</code></td> </tr> <tr> <td><code>$@</code></td> <td><code>$1 $2 $3 ... ${N}</code></td> </tr> <tr> <td><code>"$*"</code></td> <td><code>"$1c$2c$3c...c${N}"</code></td> </tr> <tr> <td><code>"$@"</code></td> <td><code>"$1" "$2" "$3" ... "${N}"</code></td> </tr> </tbody> </table> <p>Without being quoted (double quotes), both have the same effect: All positional parameters from <code>$1</code> to the last one used are expanded without any special handling.</p> <p>When the <code>$*</code> special parameter is double quoted, it expands to the equivalent of: <code>"$1c$2c$3c$4c........$N"</code>, where 'c' is the first character of <code>IFS</code>.</p> <p>But when the <code>$@</code> special parameter is used inside double quotes, it expands to the equivanent of...</p> <p><code>"$1" "$2" "$3" "$4" ..... "$N"</code></p> <p>...which <strong>reflects all positional parameters as they were set initially</strong> and passed to the script or function. If you want to re-use your positional parameters to <strong>call another program</strong> (for example in a wrapper-script), then this is the choice for you, use double quoted <code>"$@"</code>.</p> <p>Well, let's just say: <strong>You almost always want a quoted <code>"$@"</code>!</strong></p> <h3 id=range-of-positional-parameters>Range Of Positional Parameters<a class=headerlink href=#range-of-positional-parameters title="Permanent link">¶</a></h3> <p>Another way to mass expand the positional parameters is similar to what is possible for a range of characters using <a href=../../syntax/pe/#substring_expansion>substring expansion</a> on normal parameters and the mass expansion range of <a href=../../syntax/arrays/ >arrays</a>.</p> <p><code>${@:START:COUNT}</code></p> <p><code>${*:START:COUNT}</code></p> <p><code>"${@:START:COUNT}"</code></p> <p><code>"${*:START:COUNT}"</code></p> <p>The rules for using <code>@</code> or <code>*</code> and quoting are the same as above. This will expand <code>COUNT</code> number of positional parameters beginning at <code>START</code>. <code>COUNT</code> can be omitted (<code>${@:START}</code>), in which case, all positional parameters beginning at <code>START</code> are expanded.</p> <p>If <code>START</code> is negative, the positional parameters are numbered in reverse starting with the last one.</p> <p><code>COUNT</code> may not be negative, i.e. the element count may not be decremented.</p> <p><u><strong>Example:</strong></u> START at the last positional parameter:</p> <div class=highlight><pre><span></span><code>echo "${@: -1}"
|
|
</code></pre></div> <p><u><strong>Attention</strong></u>: As of Bash 4, a <code>START</code> of <code>0</code> includes the special parameter <code>$0</code>, i.e. the shell name or whatever <code>$0</code> is set to, when the positional parameters are in use. A <code>START</code> of <code>1</code> begins at <code>$1</code>. In Bash 3 and older, both <code>0</code> and <code>1</code> began at <code>$1</code>.</p> <h2 id=setting-positional-parameters>Setting Positional Parameters<a class=headerlink href=#setting-positional-parameters title="Permanent link">¶</a></h2> <p>Setting positional parameters with command line arguments, is not the only way to set them. The <a href=../../commands/builtin/set/ >builtin command, set</a> may be used to "artificially" change the positional parameters from inside the script or function:</p> <div class=highlight><pre><span></span><code>set "This is" my new "set of" positional parameters
|
|
|
|
# RESULTS IN
|
|
# $1: This is
|
|
# $2: my
|
|
# $3: new
|
|
# $4: set of
|
|
# $5: positional
|
|
# $6: parameters
|
|
</code></pre></div> <p>It's wise to signal "end of options" when setting positional parameters this way. If not, the dashes might be interpreted as an option switch by <code>set</code> itself:</p> <div class=highlight><pre><span></span><code># both ways work, but behave differently. See the article about the set command!
|
|
set -- ...
|
|
set - ...
|
|
</code></pre></div> <p>Alternately this will also preserve any verbose (-v) or tracing (-x) flags, which may otherwise be reset by <code>set</code></p> <div class=highlight><pre><span></span><code>set -$- ...
|
|
</code></pre></div> <div class="admonition warning"> <p class=admonition-title>FIXME</p> <p>continue</p> </div> <h2 id=production-examples>Production examples<a class=headerlink href=#production-examples title="Permanent link">¶</a></h2> <h3 id=using-a-while-loop>Using a while loop<a class=headerlink href=#using-a-while-loop title="Permanent link">¶</a></h3> <p>To make your program accept options as standard command syntax:</p> <p><code>COMMAND [options] <params> # Like 'cat -A file.txt'</code></p> <p>See simple option parsing code below. It's not that flexible. It doesn't auto-interpret combined options (-fu USER) but it works and is a good rudimentary way to parse your arguments.</p> <div class=highlight><pre><span></span><code>#!/bin/sh
|
|
# Keeping options in alphabetical order makes it easy to add more.
|
|
|
|
while :
|
|
do
|
|
case "$1" in
|
|
-f | --file)
|
|
file="$2" # You may want to check validity of $2
|
|
shift 2
|
|
;;
|
|
-h | --help)
|
|
display_help # Call your function
|
|
# no shifting needed here, we're done.
|
|
exit 0
|
|
;;
|
|
-u | --user)
|
|
username="$2" # You may want to check validity of $2
|
|
shift 2
|
|
;;
|
|
-v | --verbose)
|
|
# It's better to assign a string, than a number like "verbose=1"
|
|
# because if you're debugging the script with "bash -x" code like this:
|
|
#
|
|
# if [ "$verbose" ] ...
|
|
#
|
|
# You will see:
|
|
#
|
|
# if [ "verbose" ] ...
|
|
#
|
|
# Instead of cryptic
|
|
#
|
|
# if [ "1" ] ...
|
|
#
|
|
verbose="verbose"
|
|
shift
|
|
;;
|
|
--) # End of all options
|
|
shift
|
|
break;
|
|
-*)
|
|
echo "Error: Unknown option: $1" >&2
|
|
exit 1
|
|
;;
|
|
*) # No more options
|
|
break
|
|
;;
|
|
esac
|
|
done
|
|
|
|
# End of file
|
|
</code></pre></div> <h3 id=filter-unwanted-options-with-a-wrapper-script>Filter unwanted options with a wrapper script<a class=headerlink href=#filter-unwanted-options-with-a-wrapper-script title="Permanent link">¶</a></h3> <p>This simple wrapper enables filtering unwanted options (here: <code>-a</code> and <code>--all</code> for <code>ls</code>) out of the command line. It reads the positional parameters and builds a filtered array consisting of them, then calls <code>ls</code> with the new option set. It also respects the <code>--</code> as "end of options" for <code>ls</code> and doesn't change anything after it:</p> <div class=highlight><pre><span></span><code>#!/bin/bash
|
|
|
|
# simple ls(1) wrapper that doesn't allow the -a option
|
|
|
|
options=() # the buffer array for the parameters
|
|
eoo=0 # end of options reached
|
|
|
|
while [[ $1 ]]
|
|
do
|
|
if ! ((eoo)); then
|
|
case "$1" in
|
|
-a)
|
|
shift
|
|
;;
|
|
--all)
|
|
shift
|
|
;;
|
|
-[^-]*a*|-a?*)
|
|
options+=("${1//a}")
|
|
shift
|
|
;;
|
|
--)
|
|
eoo=1
|
|
options+=("$1")
|
|
shift
|
|
;;
|
|
*)
|
|
options+=("$1")
|
|
shift
|
|
;;
|
|
esac
|
|
else
|
|
options+=("$1")
|
|
|
|
# Another (worse) way of doing the same thing:
|
|
# options=("${options[@]}" "$1")
|
|
shift
|
|
fi
|
|
done
|
|
|
|
/bin/ls "${options[@]}"
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</code></pre></div> <h3 id=using-getopts>Using getopts<a class=headerlink href=#using-getopts title="Permanent link">¶</a></h3> <p>There is a <a href=../../howto/getopts_tutorial/ >small tutorial dedicated to <code>getopts</code></a> (<em>under construction</em>).</p> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">¶</a></h2> <ul> <li>Internal: <a href=../../howto/getopts_tutorial/ >getopts_tutorial</a></li> <li>Internal: <a href=../../syntax/ccmd/while_loop/ >while_loop</a></li> <li>Internal: <a href=../../syntax/ccmd/c_for/ >c_for</a></li> <li>Internal: <a href=../../syntax/arrays/ >arrays</a> (for equivalent syntax for mass-expansion)</li> <li>Internal: <a href=../../syntax/pe/#substring_expansion>Substring expansion on a parameter</a> (for equivalent syntax for mass-expansion)</li> <li>Dictionary, internal: <a href=../../dict/parameter/ >parameter</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">October 12, 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">October 12, 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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