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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=../../classictest/ class=md-nav__link> <span class=md-ellipsis> The classic test command </span> </a> </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_2_2 checked> <label class=md-nav__link for=__nav_2_2 id=__nav_2_2_label tabindex> <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=true> <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=../caller/ class=md-nav__link> <span class=md-ellipsis> The caller builtin command </span> </a> </li> <li class=md-nav__item> <a href=../cd/ class=md-nav__link> <span class=md-ellipsis> The cd builtin command </span> </a> </li> <li class=md-nav__item> <a href=../declare/ class=md-nav__link> <span class=md-ellipsis> The declare builtin command </span> </a> </li> <li class=md-nav__item> <a href=../echo/ class=md-nav__link> <span class=md-ellipsis> The echo builtin command </span> </a> </li> <li class=md-nav__item> <a href=../eval/ class=md-nav__link> <span class=md-ellipsis> The eval builtin command </span> </a> </li> <li class=md-nav__item> <a href=../exec/ class=md-nav__link> <span class=md-ellipsis> The exec builtin command </span> </a> </li> <li class=md-nav__item> <a href=../exit/ class=md-nav__link> <span class=md-ellipsis> The exit builtin command </span> </a> </li> <li class=md-nav__item> <a href=../export/ class=md-nav__link> <span class=md-ellipsis> The export builtin command </span> </a> </li> <li class=md-nav__item> <a href=../kill/ class=md-nav__link> <span class=md-ellipsis> The kill builtin command </span> </a> </li> <li class=md-nav__item> <a href=../let/ class=md-nav__link> <span class=md-ellipsis> The let builtin command </span> </a> </li> <li class=md-nav__item> <a href=../local/ class=md-nav__link> <span class=md-ellipsis> The local builtin command </span> </a> </li> <li class=md-nav__item> <a href=../mapfile/ class=md-nav__link> <span class=md-ellipsis> The mapfile builtin command </span> </a> </li> <li class=md-nav__item> <a href=../printf/ class=md-nav__link> <span class=md-ellipsis> The printf command </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> The read builtin command </span> <span class="md-nav__icon md-icon"></span> </label> <a href=./ class="md-nav__link md-nav__link--active"> <span class=md-ellipsis> The read builtin command </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=#synopsis class=md-nav__link> <span class=md-ellipsis> Synopsis </span> </a> </li> <li class=md-nav__item> <a href=#description class=md-nav__link> <span class=md-ellipsis> Description </span> </a> <nav class=md-nav aria-label=Description> <ul class=md-nav__list> <li class=md-nav__item> <a href=#options class=md-nav__link> <span class=md-ellipsis> Options </span> </a> </li> <li class=md-nav__item> <a href=#return-status class=md-nav__link> <span class=md-ellipsis> Return status </span> </a> </li> <li class=md-nav__item> <a href=#read-without-r class=md-nav__link> <span class=md-ellipsis> read without -r </span> </a> </li> </ul> </nav> </li> <li class=md-nav__item> <a href=#examples class=md-nav__link> <span class=md-ellipsis> Examples </span> </a> <nav class=md-nav aria-label=Examples> <ul class=md-nav__list> <li class=md-nav__item> <a href=#rudimentary-cat-replacement class=md-nav__link> <span class=md-ellipsis> Rudimentary cat replacement </span> </a> </li> <li class=md-nav__item> <a href=#press-any-key class=md-nav__link> <span class=md-ellipsis> Press any key... </span> </a> </li> <li class=md-nav__item> <a href=#reading-columns class=md-nav__link> <span class=md-ellipsis> Reading Columns </span> </a> <nav class=md-nav aria-label="Reading Columns"> <ul class=md-nav__list> <li class=md-nav__item> <a href=#simple-split class=md-nav__link> <span class=md-ellipsis> Simple Split </span> </a> </li> <li class=md-nav__item> <a href=#changing-the-separator class=md-nav__link> <span class=md-ellipsis> Changing The Separator </span> </a> </li> </ul> </nav> </li> <li class=md-nav__item> <a href=#are-you-sure class=md-nav__link> <span class=md-ellipsis> Are you sure? </span> </a> </li> <li class=md-nav__item> <a href=#ask-for-a-path-with-a-default-value class=md-nav__link> <span class=md-ellipsis> Ask for a path with a default value </span> </a> </li> <li class=md-nav__item> <a href=#multichar-ifs-parsing-a-simple-datetime-string class=md-nav__link> <span class=md-ellipsis> Multichar-IFS: Parsing a simple date/time string </span> </a> </li> </ul> </nav> </li> <li class=md-nav__item> <a href=#portability-considerations class=md-nav__link> <span class=md-ellipsis> Portability considerations </span> </a> </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=../readonly/ class=md-nav__link> <span class=md-ellipsis> The readonly builtin command </span> </a> </li> <li class=md-nav__item> <a href=../return/ class=md-nav__link> <span class=md-ellipsis> The return builtin command </span> </a> </li> <li class=md-nav__item> <a href=../set/ class=md-nav__link> <span class=md-ellipsis> The set builtin command </span> </a> </li> <li class=md-nav__item> <a href=../shift/ class=md-nav__link> <span class=md-ellipsis> The shift builtin command </span> </a> </li> <li class=md-nav__item> <a href=../shopt/ class=md-nav__link> <span class=md-ellipsis> The shopt builtin command </span> </a> </li> <li class=md-nav__item> <a href=../trap/ class=md-nav__link> <span class=md-ellipsis> The trap builtin command </span> </a> </li> <li class=md-nav__item> <a href=../unset/ class=md-nav__link> <span class=md-ellipsis> The unset builtin command </span> </a> </li> <li class=md-nav__item> <a href=../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--nested"> <input class="md-nav__toggle md-toggle " type=checkbox id=__nav_7> <label class=md-nav__link for=__nav_7 id=__nav_7_label tabindex=0> <span class=md-ellipsis> Scripting </span> <span class="md-nav__icon md-icon"></span> </label> <nav class=md-nav data-md-level=1 aria-labelledby=__nav_7_label aria-expanded=false> <label class=md-nav__title for=__nav_7> <span class="md-nav__icon md-icon"></span> Scripting </label> <ul class=md-nav__list data-md-scrollfix> <li class=md-nav__item> <a href=../../../scripting/bashbehaviour/ class=md-nav__link> <span class=md-ellipsis> Bash's behaviour </span> </a> </li> <li class=md-nav__item> <a href=../../../scripting/bashchanges/ class=md-nav__link> <span class=md-ellipsis> Bash changes </span> </a> </li> <li class=md-nav__item> <a href=../../../scripting/basics/ class=md-nav__link> <span class=md-ellipsis> The basics of shell scripting </span> </a> </li> <li class=md-nav__item> <a href=../../../scripting/debuggingtips/ class=md-nav__link> <span class=md-ellipsis> Debugging a script </span> </a> </li> <li class=md-nav__item> <a href=../../../scripting/newbie_traps/ class=md-nav__link> <span class=md-ellipsis> Beginner Mistakes </span> </a> </li> <li class=md-nav__item> <a href=../../../scripting/nonportable/ class=md-nav__link> <span class=md-ellipsis> Portability talk </span> </a> </li> <li class=md-nav__item> <a href=../../../scripting/obsolete/ class=md-nav__link> <span class=md-ellipsis> Obsolete and deprecated syntax </span> </a> </li> <li class=md-nav__item> <a href=../../../scripting/posparams/ class=md-nav__link> <span class=md-ellipsis> Handling positional parameters </span> </a> </li> <li class=md-nav__item> <a href=../../../scripting/processtree/ class=md-nav__link> <span class=md-ellipsis> Bash and the process tree </span> </a> </li> <li class=md-nav__item> <a href=../../../scripting/style/ class=md-nav__link> <span class=md-ellipsis> Scripting with style </span> </a> </li> <li class=md-nav__item> <a href=../../../scripting/terminalcodes/ class=md-nav__link> <span class=md-ellipsis> Terminal codes (ANSI/VT100) introduction </span> </a> </li> </ul> </nav> </li> <li class="md-nav__item md-nav__item--nested"> <input class="md-nav__toggle md-toggle " type=checkbox id=__nav_8> <label class=md-nav__link for=__nav_8 id=__nav_8_label tabindex=0> <span class=md-ellipsis> Snipplets </span> <span class="md-nav__icon md-icon"></span> </label> <nav class=md-nav data-md-level=1 aria-labelledby=__nav_8_label aria-expanded=false> <label class=md-nav__title for=__nav_8> <span class="md-nav__icon md-icon"></span> Snipplets </label> <ul class=md-nav__list data-md-scrollfix> <li class=md-nav__item> <a href=../../../snipplets/ class=md-nav__link> <span class=md-ellipsis> Small code snipplets </span> </a> </li> <li class=md-nav__item> <a href=../../../snipplets/add_color_to_your_scripts/ class=md-nav__link> <span class=md-ellipsis> Add Color to your scripts </span> </a> </li> <li class=md-nav__item> <a href=../../../snipplets/awkcsv/ class=md-nav__link> <span class=md-ellipsis> Using awk to deal with CSV that uses quoted/unquoted delimiters </span> </a> </li> <li class=md-nav__item> <a href=../../../snipplets/filesize/ class=md-nav__link> <span class=md-ellipsis> Show size of a file </span> </a> </li> <li class=md-nav__item> <a href=../../../snipplets/kill_bg_job_without_message/ class=md-nav__link> <span class=md-ellipsis> Kill a background job without a message </span> </a> </li> <li class=md-nav__item> <a href=../../../snipplets/largestfile/ class=md-nav__link> <span class=md-ellipsis> Get largest file </span> </a> </li> <li class=md-nav__item> <a href=../../../snipplets/pause_command/ class=md-nav__link> <span class=md-ellipsis> Pausing a script (like MSDOS pause command) </span> </a> </li> <li class=md-nav__item> <a href=../../../snipplets/prargs/ class=md-nav__link> <span class=md-ellipsis> Print argument list for testing </span> </a> </li> <li class=md-nav__item> <a href=../../../snipplets/print_horizontal_line/ class=md-nav__link> <span class=md-ellipsis> Print a horizontal line </span> </a> </li> <li class=md-nav__item> <a href=../../../snipplets/rndstr/ class=md-nav__link> <span class=md-ellipsis> Print a random string or select random elements </span> </a> </li> <li class=md-nav__item> <a href=../../../snipplets/screen_saverestore/ class=md-nav__link> <span class=md-ellipsis> Save and restore terminal/screen content </span> </a> </li> <li class=md-nav__item> <a href=../../../snipplets/ssh_fetchkeys/ class=md-nav__link> <span class=md-ellipsis> Fetching SSH hostkeys without interaction </span> </a> </li> <li class=md-nav__item> <a href=../../../snipplets/ssh_local_var/ class=md-nav__link> <span class=md-ellipsis> Run some bash commands with SSH remotely using local variables </span> </a> </li> <li class=md-nav__item> <a href=../../../snipplets/wrapperargs/ class=md-nav__link> <span class=md-ellipsis> Generate code with own arguments properly quoted </span> </a> </li> <li class=md-nav__item> <a href=../../../snipplets/xclip/ class=md-nav__link> <span class=md-ellipsis> X-Clipboard on Commandline </span> </a> </li> </ul> </nav> </li> <li class="md-nav__item md-nav__item--nested"> <input class="md-nav__toggle md-toggle " type=checkbox id=__nav_9> <label class=md-nav__link for=__nav_9 id=__nav_9_label tabindex=0> <span class=md-ellipsis> Syntax </span> <span class="md-nav__icon md-icon"></span> </label> <nav class=md-nav data-md-level=1 aria-labelledby=__nav_9_label aria-expanded=false> <label class=md-nav__title for=__nav_9> <span class="md-nav__icon md-icon"></span> Syntax </label> <ul class=md-nav__list data-md-scrollfix> <li class=md-nav__item> <a href=../../../syntax/arith_expr/ class=md-nav__link> <span class=md-ellipsis> Arithmetic expressions </span> </a> </li> <li class=md-nav__item> <a href=../../../syntax/arrays/ class=md-nav__link> <span class=md-ellipsis> Arrays </span> </a> </li> <li class=md-nav__item> <a href=../../../syntax/basicgrammar/ class=md-nav__link> <span class=md-ellipsis> Basic grammar rules of Bash </span> </a> </li> <li class=md-nav__item> <a href=../../../syntax/pattern/ class=md-nav__link> <span class=md-ellipsis> Patterns and pattern matching </span> </a> </li> <li class=md-nav__item> <a href=../../../syntax/pe/ class=md-nav__link> <span class=md-ellipsis> Parameter expansion </span> </a> </li> <li class=md-nav__item> <a href=../../../syntax/quoting/ class=md-nav__link> <span class=md-ellipsis> Quotes and escaping </span> </a> </li> <li class=md-nav__item> <a href=../../../syntax/redirection/ class=md-nav__link> <span class=md-ellipsis> Redirection </span> </a> </li> <li class=md-nav__item> <a href=../../../syntax/shellvars/ class=md-nav__link> <span class=md-ellipsis> Special parameters and shell variables </span> </a> </li> <li class=md-nav__item> <a href=../../../syntax/words/ class=md-nav__link> <span class=md-ellipsis> Words... </span> </a> </li> <li class="md-nav__item md-nav__item--nested"> <input class="md-nav__toggle md-toggle " type=checkbox id=__nav_9_10> <label class=md-nav__link for=__nav_9_10 id=__nav_9_10_label tabindex=0> <span class=md-ellipsis> Ccmd </span> <span class="md-nav__icon md-icon"></span> </label> <nav class=md-nav data-md-level=2 aria-labelledby=__nav_9_10_label aria-expanded=false> <label class=md-nav__title for=__nav_9_10> <span class="md-nav__icon md-icon"></span> Ccmd </label> <ul class=md-nav__list data-md-scrollfix> <li class=md-nav__item> <a href=../../../syntax/ccmd/arithmetic_eval/ class=md-nav__link> <span class=md-ellipsis> Arithmetic evaluation (command) </span> </a> </li> <li class=md-nav__item> <a href=../../../syntax/ccmd/c_for/ class=md-nav__link> <span class=md-ellipsis> The C-style for-loop </span> </a> </li> <li class=md-nav__item> <a href=../../../syntax/ccmd/case/ class=md-nav__link> <span class=md-ellipsis> The case statement </span> </a> </li> <li class=md-nav__item> <a href=../../../syntax/ccmd/classic_for/ class=md-nav__link> <span class=md-ellipsis> The classic for-loop </span> </a> </li> <li class=md-nav__item> <a href=../../../syntax/ccmd/conditional_expression/ class=md-nav__link> <span class=md-ellipsis> The conditional expression </span> </a> </li> <li class=md-nav__item> <a href=../../../syntax/ccmd/grouping_plain/ class=md-nav__link> <span class=md-ellipsis> Grouping commands </span> </a> </li> <li class=md-nav__item> <a href=../../../syntax/ccmd/grouping_subshell/ class=md-nav__link> <span class=md-ellipsis> Grouping commands in a subshell </span> </a> </li> <li class=md-nav__item> <a href=../../../syntax/ccmd/if_clause/ class=md-nav__link> <span class=md-ellipsis> The if-clause </span> </a> </li> <li class=md-nav__item> <a href=../../../syntax/ccmd/intro/ class=md-nav__link> <span class=md-ellipsis> Bash compound commands </span> </a> </li> <li class=md-nav__item> <a href=../../../syntax/ccmd/until_loop/ class=md-nav__link> <span class=md-ellipsis> The until loop </span> </a> </li> <li class=md-nav__item> <a href=../../../syntax/ccmd/user_select/ class=md-nav__link> <span class=md-ellipsis> User selections </span> </a> </li> <li class=md-nav__item> <a href=../../../syntax/ccmd/while_loop/ class=md-nav__link> <span class=md-ellipsis> The while-loop </span> </a> </li> </ul> </nav> </li> <li class="md-nav__item md-nav__item--nested"> <input class="md-nav__toggle md-toggle " type=checkbox id=__nav_9_11> <label class=md-nav__link for=__nav_9_11 id=__nav_9_11_label tabindex=0> <span class=md-ellipsis> Expansion </span> <span class="md-nav__icon md-icon"></span> </label> <nav class=md-nav data-md-level=2 aria-labelledby=__nav_9_11_label aria-expanded=false> <label class=md-nav__title for=__nav_9_11> <span class="md-nav__icon md-icon"></span> Expansion </label> <ul class=md-nav__list data-md-scrollfix> <li class=md-nav__item> <a href=../../../syntax/expansion/arith/ class=md-nav__link> <span class=md-ellipsis> Arithmetic expansion </span> </a> </li> <li class=md-nav__item> <a href=../../../syntax/expansion/brace/ class=md-nav__link> <span class=md-ellipsis> Brace expansion </span> </a> </li> <li class=md-nav__item> <a href=../../../syntax/expansion/cmdsubst/ class=md-nav__link> <span class=md-ellipsis> Command substitution </span> </a> </li> <li class=md-nav__item> <a href=../../../syntax/expansion/globs/ class=md-nav__link> <span class=md-ellipsis> Pathname expansion (globbing) </span> </a> </li> <li class=md-nav__item> <a href=../../../syntax/expansion/intro/ class=md-nav__link> <span class=md-ellipsis> Expansions and substitutions </span> </a> </li> <li class=md-nav__item> <a href=../../../syntax/expansion/proc_subst/ class=md-nav__link> <span class=md-ellipsis> Process substitution </span> </a> </li> <li class=md-nav__item> <a href=../../../syntax/expansion/tilde/ class=md-nav__link> <span class=md-ellipsis> Tilde expansion </span> </a> </li> <li class=md-nav__item> <a href=../../../syntax/expansion/wordsplit/ class=md-nav__link> <span class=md-ellipsis> Word splitting </span> </a> </li> </ul> </nav> </li> <li class="md-nav__item md-nav__item--nested"> <input class="md-nav__toggle md-toggle " type=checkbox id=__nav_9_12> <label class=md-nav__link for=__nav_9_12 id=__nav_9_12_label tabindex=0> <span class=md-ellipsis> Grammar </span> <span class="md-nav__icon md-icon"></span> </label> <nav class=md-nav data-md-level=2 aria-labelledby=__nav_9_12_label aria-expanded=false> <label class=md-nav__title for=__nav_9_12> <span class="md-nav__icon md-icon"></span> Grammar </label> <ul class=md-nav__list data-md-scrollfix> <li class=md-nav__item> <a href=../../../syntax/grammar/parser_exec/ class=md-nav__link> <span class=md-ellipsis> Parser exec </span> </a> </li> </ul> </nav> </li> <li class="md-nav__item md-nav__item--nested"> <input class="md-nav__toggle md-toggle " type=checkbox id=__nav_9_13> <label class=md-nav__link for=__nav_9_13 id=__nav_9_13_label tabindex=0> <span class=md-ellipsis> Keywords </span> <span class="md-nav__icon md-icon"></span> </label> <nav class=md-nav data-md-level=2 aria-labelledby=__nav_9_13_label aria-expanded=false> <label class=md-nav__title for=__nav_9_13> <span class="md-nav__icon md-icon"></span> Keywords </label> <ul class=md-nav__list data-md-scrollfix> <li class=md-nav__item> <a href=../../../syntax/keywords/coproc/ class=md-nav__link> <span class=md-ellipsis> The coproc keyword </span> </a> </li> </ul> </nav> </li> </ul> </nav> </li> <li class=md-nav__item> <a href=../../../tags/ class=md-nav__link> <span class=md-ellipsis> Tags </span> </a> </li> </ul> </nav> </div> </div> </div> <div class="md-sidebar md-sidebar--secondary" data-md-component=sidebar data-md-type=toc> <div class=md-sidebar__scrollwrap> <div class=md-sidebar__inner> <nav class="md-nav md-nav--secondary" aria-label="Table of contents"> <label class=md-nav__title for=__toc> <span class="md-nav__icon md-icon"></span> Table of contents </label> <ul class=md-nav__list data-md-component=toc data-md-scrollfix> <li class=md-nav__item> <a href=#synopsis class=md-nav__link> <span class=md-ellipsis> Synopsis </span> </a> </li> <li class=md-nav__item> <a href=#description class=md-nav__link> <span class=md-ellipsis> Description </span> </a> <nav class=md-nav aria-label=Description> <ul class=md-nav__list> <li class=md-nav__item> <a href=#options class=md-nav__link> <span class=md-ellipsis> Options </span> </a> </li> <li class=md-nav__item> <a href=#return-status class=md-nav__link> <span class=md-ellipsis> Return status </span> </a> </li> <li class=md-nav__item> <a href=#read-without-r class=md-nav__link> <span class=md-ellipsis> read without -r </span> </a> </li> </ul> </nav> </li> <li class=md-nav__item> <a href=#examples class=md-nav__link> <span class=md-ellipsis> Examples </span> </a> <nav class=md-nav aria-label=Examples> <ul class=md-nav__list> <li class=md-nav__item> <a href=#rudimentary-cat-replacement class=md-nav__link> <span class=md-ellipsis> Rudimentary cat replacement </span> </a> </li> <li class=md-nav__item> <a href=#press-any-key class=md-nav__link> <span class=md-ellipsis> Press any key... </span> </a> </li> <li class=md-nav__item> <a href=#reading-columns class=md-nav__link> <span class=md-ellipsis> Reading Columns </span> </a> <nav class=md-nav aria-label="Reading Columns"> <ul class=md-nav__list> <li class=md-nav__item> <a href=#simple-split class=md-nav__link> <span class=md-ellipsis> Simple Split </span> </a> </li> <li class=md-nav__item> <a href=#changing-the-separator class=md-nav__link> <span class=md-ellipsis> Changing The Separator </span> </a> </li> </ul> </nav> </li> <li class=md-nav__item> <a href=#are-you-sure class=md-nav__link> <span class=md-ellipsis> Are you sure? </span> </a> </li> <li class=md-nav__item> <a href=#ask-for-a-path-with-a-default-value class=md-nav__link> <span class=md-ellipsis> Ask for a path with a default value </span> </a> </li> <li class=md-nav__item> <a href=#multichar-ifs-parsing-a-simple-datetime-string class=md-nav__link> <span class=md-ellipsis> Multichar-IFS: Parsing a simple date/time string </span> </a> </li> </ul> </nav> </li> <li class=md-nav__item> <a href=#portability-considerations class=md-nav__link> <span class=md-ellipsis> Portability considerations </span> </a> </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"> <a href=https://github.com/flokoe/bash-hackers-wiki/edit/main/docs/commands/builtin/read.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/commands/builtin/read.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=the-read-builtin-command>The read builtin command<a class=headerlink href=#the-read-builtin-command title="Permanent link">¶</a></h1> <p><em>read something about read here!</em></p> <h2 id=synopsis>Synopsis<a class=headerlink href=#synopsis title="Permanent link">¶</a></h2> <div class=highlight><pre><span></span><code>read [-ers] [-u <FD>] [-t <TIMEOUT>] [-p <PROMPT>] [-a <ARRAY>] [-n <NCHARS>] [-N <NCHARS>] [-d <DELIM>] [-i <TEXT>] [<NAME...>]
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</code></pre></div> <h2 id=description>Description<a class=headerlink href=#description title="Permanent link">¶</a></h2> <p>The <code>read</code> builtin reads <strong>one line</strong> of data (text, user input, ...) from standard input or a supplied filedescriptor number into one or more variables named by <code><NAME...></code>.</p> <p>Since Bash 4.3-alpha, <code>read</code> skips any <code>NUL</code> (ASCII code 0) characters in input.</p> <p>If <code><NAME...></code> is given, the line is word-split using <a href=../../../syntax/shellvars/#IFS>IFS</a> variable, and every word is assigned to one <code><NAME></code>. The remaining words are all assigned to the last <code><NAME></code> if more words than variable names are present.</p> <p><wrap center round info 90%> If no <code><NAME></code> is given, the whole line read (without performing word-splitting!) is assigned to the shell variable <a href=../../../syntax/shellvars/#REPLY>REPLY</a>. Then, <code>REPLY</code> really contains the line as it was read, without stripping pre- and postfix spaces and other things!</p> <div class=highlight><pre><span></span><code>while read -r; do
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printf '"%s"\n' "$REPLY"
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done <<<" a line with prefix and postfix space "
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</code></pre></div> <p></wrap></p> <p>If a timeout is given, or if the shell variable <a href=../../../syntax/shellvars/#TMOUT>TMOUT</a> is set, it is counted from initially waiting for input until the completion of input (i.e. until the complete line is read). That means the timeout can occur during input, too.</p> <h3 id=options>Options<a class=headerlink href=#options title="Permanent link">¶</a></h3> <p>Option Description</p> <hr> <p><code>-a <ARRAY></code> read the data word-wise into the specified array <code><ARRAY></code> instead of normal variables <code>-d <DELIM></code> recognize <code><DELIM></code> as data-end, rather than <code><newline></code> <code>-e</code> on interactive shells: use Bash's readline interface to read the data. Since version 5.1-alpha, this can also be used on specified file descriptors using <code>-u</code> <code>-i <STRING></code> preloads the input buffer with text from <code><STRING></code>, only works when Readline (<code>-e</code>) is used <code>-n <NCHARS></code> reads <code><NCHARS></code> characters of input, then quits <code>-N <NCHARS></code> reads <code><NCHARS></code> characters of input, <em>ignoring any delimiter</em>, then quits <code>-p <PROMPT></code> the prompt string <code><PROMPT></code> is output (without a trailing automatic newline) before the read is performed <code>-r</code> raw input - <strong>disables</strong> interpretion of <strong>backslash escapes</strong> and <strong>line-continuation</strong> in the read data <code>-s</code> secure input - don't echo input if on a terminal (passwords!) <code>-t <TIMEOUT></code> wait for data <code><TIMEOUT></code> seconds, then quit (exit code 1). Fractional seconds ("5.33") are allowed since Bash 4. A value of 0 immediately returns and indicates if data is waiting in the exit code. Timeout is indicated by an exit code greater than 128. If timeout arrives before data is read completely (before end-of-line), the partial data is saved. <code>-u <FD></code> use the filedescriptor number <code><FD></code> rather than <code>stdin</code> (0)</p> <p>When both, <code>-a <ARRAY></code> and a variable name <code><NAME></code> is given, then the array is set, but not the variable.</p> <p>Of course it's valid to set individual array elements without using <code>-a</code>:</p> <div class=highlight><pre><span></span><code>read MYARRAY[5]
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</code></pre></div> <p><wrap center round important 90%></p> <p>Reading into array elements using the syntax above <strong>may cause <a href=../../../syntax/expansion/globs/ >pathname expansion</a> to occur</strong>.</p> <p>Example: You are in a directory with a file named <code>x1</code>, and you want to read into an array <code>x</code>, index <code>1</code> with</p> <div class=highlight><pre><span></span><code>read x[1]
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</code></pre></div> <p>then pathname expansion will expand to the filename <code>x1</code> and break your processing!</p> <p>Even worse, if <code>nullglob</code> is set, your array/index will disappear.</p> <p>To avoid this, either <strong>disable pathname expansion</strong> or <strong>quote</strong> the array name and index:</p> <div class=highlight><pre><span></span><code>read 'x[1]'
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</code></pre></div> <p></wrap></p> <h3 id=return-status>Return status<a class=headerlink href=#return-status title="Permanent link">¶</a></h3> <p>Status Reason</p> <hr> <p>0 no error 0 error when assigning to a read-only variable <sup id=fnref:1><a class=footnote-ref href=#fn:1>1</a></sup> 2 invalid option</p> <blockquote> <p>128 timeout (see <code>-t</code>) !=0 invalid filedescriptor supplied to <code>-u</code> !=0 end-of-file reached</p> </blockquote> <h3 id=read-without-r>read without -r<a class=headerlink href=#read-without-r title="Permanent link">¶</a></h3> <p>Essentially all you need to know about <code>-r</code> is to <strong>ALWAYS</strong> use it. The exact behavior you get without <code>-r</code> is completely useless even for weird purposes. It basically allows the escaping of input which matches something in IFS, and also escapes line continuations. It's explained pretty well in the <a href=http://pubs.opengroup.org/onlinepubs/9699919799/utilities/read.html#tag_20_109>POSIX read</a> spec.</p> <div class=highlight><pre><span></span><code>2012-05-23 13:48:31 geirha it should only remove the backslashes, not change \n and \t and such into newlines and tabs
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2012-05-23 13:49:00 ormaaj so that's what read without -r does?
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2012-05-23 13:49:16 geirha no, -r doesn't remove the backslashes
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2012-05-23 13:49:34 ormaaj I thought read <<<'str' was equivalent to read -r <<<$'str'
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2012-05-23 13:49:38 geirha # read x y <<< 'foo\ bar baz'; echo "<$x><$y>"
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2012-05-23 13:49:40 shbot geirha: <foo bar><baz>
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2012-05-23 13:50:32 geirha no, read without -r is mostly pointless. Damn bourne
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2012-05-23 13:51:08 ormaaj So it's mostly (entirely) used to escape spaces
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2012-05-23 13:51:24 ormaaj and insert newlines
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2012-05-23 13:51:47 geirha ormaaj: you mostly get the same effect as using \ at the prompt
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2012-05-23 13:52:04 geirha echo \" outputs a " , read x <<< '\"' reads a "
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2012-05-23 13:52:32 ormaaj oh weird
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2012-05-23 13:52:46 * ormaaj struggles to think of a point to that...
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2012-05-23 13:53:01 geirha ormaaj: ask Bourne :P
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2012-05-23 13:53:20 geirha (not Jason)
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2012-05-23 13:53:56 ormaaj hm thanks anyway :)
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</code></pre></div> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">¶</a></h2> <h3 id=rudimentary-cat-replacement>Rudimentary cat replacement<a class=headerlink href=#rudimentary-cat-replacement title="Permanent link">¶</a></h3> <p>A rudimentary replacement for the <code>cat</code> command: read lines of input from a file and print them on the terminal.</p> <div class=highlight><pre><span></span><code>opossum() {
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while read -r; do
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printf "%s\n" "$REPLY"
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done <"$1"
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}
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</code></pre></div> <p><u><strong>Note:</strong></u> Here, <code>read -r</code> and the default <code>REPLY</code> is used, because we want to have the real literal line, without any mangeling. <code>printf</code> is used, because (depending on settings), <code>echo</code> may interpret some baskslash-escapes or switches (like <code>-n</code>).</p> <h3 id=press-any-key>Press any key...<a class=headerlink href=#press-any-key title="Permanent link">¶</a></h3> <p>Remember the MSDOS <code>pause</code> command? Here's something similar:</p> <div class=highlight><pre><span></span><code>pause() {
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local dummy
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read -s -r -p "Press any key to continue..." -n 1 dummy
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}
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</code></pre></div> <p>Notes:</p> <ul> <li><code>-s</code> to suppress terminal echo (printing)</li> <li><code>-r</code> to not interpret special characters (like waiting for a second character if somebody presses the backslash)</li> </ul> <h3 id=reading-columns>Reading Columns<a class=headerlink href=#reading-columns title="Permanent link">¶</a></h3> <h4 id=simple-split>Simple Split<a class=headerlink href=#simple-split title="Permanent link">¶</a></h4> <p>Read can be used to split a string:</p> <div class=highlight><pre><span></span><code>var="one two three"
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read -r col1 col2 col3 <<< "$var"
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printf "col1: %s col2: %s col3 %s\n" "$col1" "$col2" "$col3"
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</code></pre></div> <p>Take care that you cannot use a pipe:</p> <div class=highlight><pre><span></span><code>echo "$var" | read col1 col2 col3 # does not work!
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printf "col1: %s col2: %s col3 %s\n" "$col1" "$col2" "$col3"
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</code></pre></div> <p>Why? because the commands of the pipe run in subshells that cannot modify the parent shell. As a result, the variables <code>col1</code>, <code>col2</code> and <code>col3</code> of the parent shell are not modified (see article: <a href=../../../scripting/processtree/ >processtree</a>).</p> <p>If the variable has more fields than there are variables, the last variable get the remaining of the line:</p> <div class=highlight><pre><span></span><code>read col1 col2 col3 <<< "one two three four"
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printf "%s\n" "$col3" #prints three four
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</code></pre></div> <h4 id=changing-the-separator>Changing The Separator<a class=headerlink href=#changing-the-separator title="Permanent link">¶</a></h4> <p>By default reads separates the line in fields using spaces or tabs. You can modify this using the <em>special variable</em> <a href=../../../syntax/shellvars/#IFS>IFS</a>, the Internal Field Separator.</p> <div class=highlight><pre><span></span><code>IFS=":" read -r col1 col2 <<< "hello:world"
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printf "col1: %s col2: %s\n" "$col1" "$col2"
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</code></pre></div> <p>Here we use the <code>var=value command</code> syntax to set the environment of <code>read</code> temporarily. We could have set <code>IFS</code> normally, but then we would have to take care to save its value and restore it afterward (<code>OLD=$IFS IFS=":"; read ....;IFS=$OLD</code>).</p> <p>The default <code>IFS</code> is special in that 2 fields can be separated by one or more space or tab. When you set <code>IFS</code> to something besides whitespace (space or tab), the fields are separated by <strong>exactly</strong> one character:</p> <div class=highlight><pre><span></span><code>IFS=":" read -r col1 col2 col3 <<< "hello::world"
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printf "col1: %s col2: %s col3 %s\n" "$col1" "$col2" "$col3"
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</code></pre></div> <p>See how the <code>::</code> in the middle infact defines an additional <em>empty field</em>.</p> <p>The fields are separated by exactly one character, but the character can be different between each field:</p> <div class=highlight><pre><span></span><code>IFS=":|@" read -r col1 col2 col3 col4 <<< "hello:world|in@bash"
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printf "col1: %s col2: %s col3 %s col4 %s\n" "$col1" "$col2" "$col3" "$col4"
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</code></pre></div> <h3 id=are-you-sure>Are you sure?<a class=headerlink href=#are-you-sure title="Permanent link">¶</a></h3> <div class=highlight><pre><span></span><code>asksure() {
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echo -n "Are you sure (Y/N)? "
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while read -r -n 1 -s answer; do
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if [[ $answer = [YyNn] ]]; then
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[[ $answer = [Yy] ]] && retval=0
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[[ $answer = [Nn] ]] && retval=1
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break
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fi
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done
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echo # just a final linefeed, optics...
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return $retval
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}
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### using it
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if asksure; then
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echo "Okay, performing rm -rf / then, master...."
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else
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echo "Pfff..."
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fi
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</code></pre></div> <h3 id=ask-for-a-path-with-a-default-value>Ask for a path with a default value<a class=headerlink href=#ask-for-a-path-with-a-default-value title="Permanent link">¶</a></h3> <p><u><strong>Note:</strong></u> The <code>-i</code> option was introduced with Bash 4</p> <div class=highlight><pre><span></span><code>read -e -p "Enter the path to the file: " -i "/usr/local/etc/" FILEPATH
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</code></pre></div> <p>The user will be prompted, he can just accept the default, or edit it.</p> <h3 id=multichar-ifs-parsing-a-simple-datetime-string>Multichar-IFS: Parsing a simple date/time string<a class=headerlink href=#multichar-ifs-parsing-a-simple-datetime-string title="Permanent link">¶</a></h3> <p>Here, <code>IFS</code> contains both, a colon and a space. The fields of the date/time string are recognized correctly.</p> <div class=highlight><pre><span></span><code>datetime="2008:07:04 00:34:45"
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IFS=": " read -r year month day hour minute second <<< "$datetime"
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</code></pre></div> <h2 id=portability-considerations>Portability considerations<a class=headerlink href=#portability-considerations title="Permanent link">¶</a></h2> <ul> <li>POSIX® only specified the <code>-r</code> option (raw read); <code>-r</code> is not only POSIX, you can find it in earlier Bourne source code</li> <li>POSIX® doesn't support arrays</li> <li><code>REPLY</code> is not POSIX®, you need to set <code>IFS</code> to the empty string to get the whole line for shells that don't know <code>REPLY</code>. <code>while IFS= read -r line; do ... done < text.txt</code></li> </ul> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">¶</a></h2> <ul> <li>Internal: <a href=../printf/ >The printf builtin command</a></li> </ul> <div class=footnote> <hr> <ol> <li id=fn:1> <p>fixed in 4.2-rc1 <a class=footnote-backref href=#fnref:1 title="Jump back to footnote 1 in the text">↩</a></p> </li> </ol> </div> <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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