# Test (Unix) > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Test_(Unix) > Markdown URL: https://mediated.wiki/source/Test_(Unix).md > Source: https://en.wikipedia.org/wiki/Test_(Unix) > Source revision: 1353506959 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) {{short description|Command-line utility}} {{Lowercase title}} {{Infobox software | name = test | logo = | screenshot = | screenshot size = | caption = | developer = Various [open-source](/source/open-source_software) and [commercial](/source/commercial_software) developers | released = | other_names = [ | latest release version = | latest release date = | programming language = [C](/source/C_(programming_language)) | operating system = [Unix](/source/Unix), [Unix-like](/source/Unix-like), [Plan 9](/source/Plan_9_from_Bell_Labs), [IBM i](/source/IBM_i) | platform = [Cross-platform](/source/Cross-platform) | genre = [Command](/source/Command_(computing)) | license = [coreutils](/source/coreutils): [GPLv3+](/source/GPLv3%2B)
Plan 9: [MIT License](/source/MIT_License) | website = }} '''test''' is a [command-line](/source/command_line_interface) utility found in [Unix](/source/Unix), [Plan 9](/source/Plan_9_from_Bell_Labs), and [Unix-like](/source/Unix-like) operating systems that evaluates [conditional expressions](/source/Conditional_(programming)). '''test''' was turned into a shell builtin command in 1981 with [UNIX System III](/source/UNIX_System_III) and at the same time made available under the alternate name '''['''.http://www.in-ulm.de/~mascheck/bourne/#system3 {{Webarchive|url=https://web.archive.org/web/20190504035047/https://www.in-ulm.de/~mascheck/bourne/PWB/#system3 |date=2019-05-04 }} Bourne Shell changes with System III ==Overview== The test command in Unix evaluates the expression parameter. In most recent shell implementations, it is a [shell builtin](/source/shell_builtin), even though the external version still exists. In the second form of the command, the [ ] (brackets) must be surrounded by blank spaces (this is because [ is a program and [POSIX](/source/POSIX) compatible shells require a space between the program name and its arguments). One must test explicitly for file names in the [C shell](/source/C_shell). File-name substitution ([globbing](/source/glob_(programming))) causes the shell script to exit. The test command is not to be confused with the [[ reserved word that was introduced with ksh88. The latter is not a command but part of the ksh88 syntax and does not apply file-name substitution to glob expressions. The version of test bundled in [GNU](/source/GNU) [coreutils](/source/coreutils) was written by Kevin Braunsdorf and Matthew Bradburn.{{Cite web |url=https://manpages.debian.org/buster/coreutils/test.1.en.html |title=test(1) — coreutils — Debian buster — Debian Manpages |access-date=2020-07-12 |archive-date=2020-07-12 |archive-url=https://web.archive.org/web/20200712145342/https://manpages.debian.org/buster/coreutils/test.1.en.html |url-status=live }} The command is available as a separate package for [Microsoft Windows](/source/Microsoft_Windows) as part of the [UnxUtils](/source/UnxUtils) collection of [native](/source/Native_(computing)) [Win32](/source/Windows_API) [ports](/source/porting) of common GNU Unix-like utilities.{{Cite web|url=https://unxutils.sourceforge.net/|title=Native Win32 ports of some GNU utilities|website=unxutils.sourceforge.net|access-date=2025-08-11|archive-date=2006-02-09|archive-url=https://web.archive.org/web/20060209022842/http://unxutils.sourceforge.net/|url-status=live}} The {{Mono|test}} command has also been ported to the [IBM i](/source/IBM_i) operating system.{{cite web |title=IBM System i Version 7.2 Programming Qshell |language=en |author=IBM |website=[IBM](/source/IBM) |author-link=IBM |url=https://www.ibm.com/support/knowledgecenter/ssw_ibm_i_74/rzahz/rzahzpdf.pdf?view=kc |access-date=2020-09-05 |archive-date=2020-09-18 |archive-url=https://web.archive.org/web/20200918130823/https://www.ibm.com/support/knowledgecenter/ssw_ibm_i_74/rzahz/rzahzpdf.pdf?view=kc |url-status=live }} ==Syntax== test ''expression'' or [ ''expression'' ] ===Arguments=== The following arguments are used to construct this parameter. All arguments return True if the object (file or string) exists, and the condition specified is true. {| class="wikitable" |- ! Argument ! Returns True if the file |- | -b || is a block special file |- | -c || is a [character special file](/source/character_special_file) |- | -d || is a [directory](/source/directory_(file_systems)) |- | -e || exists |- | -f || is a regular file |- | -g || has the Set [Group ID](/source/Group_identifier_(Unix)) bit set |- | -h || is a [symbolic link](/source/symbolic_link) |- | -k || has the sticky bit set |- | -L || is a [symbolic link](/source/symbolic_link) |- | -p || is a [named pipe](/source/named_pipe) (FIFO) |- | -r || is readable by the current process |- | -s || has a size greater than 0 |- | -t || [FileDescriptor](/source/File_descriptor) is open and associated with a [terminal](/source/pseudo_terminal) |- | -u || has the Set [User ID](/source/User_identifier_(Unix)) bit set |- | -w || has the write flag is on |- | -x || has [execute](/source/Execution_(computers)) flag on |} For the -x argument, if the specified file exists and is a directory, the True exit value indicates that the current process has permission to change cd into the directory. ====Non standard [Korn Shell](/source/Korn_Shell) extensions==== file1 '''-nt''' file2 - file1 is newer than file2 file1 '''-ot''' file2 - file1 is older than file2 file1 '''-ef''' file2 - file1 is another name for file2 - ([symbolic link](/source/symbolic_link) or [hard link](/source/hard_link)) ====String arguments==== In [Perl](/source/Perl), these sections are reversed: eq is a string operator and == is a numerical operator, and so on for the others. '''-n''' String1 - the length of the String1 variable is nonzero '''-z''' String1 - the length of the String1 variable is 0 (zero) String1 '''=''' String2 - String1 and String2 variables are identical String1 '''!=''' String2 - String1 and String2 variables are not identical String1 - true if String1 variable is not a null string ====Number arguments==== Integer1 '''-eq''' Integer2 - Integer1 and Integer2 variables are [algebra](/source/algebra)ically equal '''-ne''' - not equal '''-gt''' - greater than '''-ge''' - greater or equal '''-lt''' - less than '''-le''' - less or equal ====Operators==== test arguments can be combined with the following operators: '''!''' - Unary negation operator '''-a''' - Binary AND operator '''-o''' - Binary OR operator (the -a operator has higher precedence than the -o operator) '''\(Expression\)''' - Parentheses for grouping must be escaped with a backslash \ The -a and -o operators, along with parentheses for grouping, are XSI extensions{{Cite web |url=http://www.opengroup.org/onlinepubs/009695399/utilities/test.html |title=IEEE Std 1003.1, 2004, documentation for test |access-date=2006-11-08 |archive-date=2008-07-08 |archive-url=https://web.archive.org/web/20080708224750/http://www.opengroup.org/onlinepubs/009695399/utilities/test.html |url-status=live }} and are therefore not portable. In portable shell scripts, the same effect may be achieved by connecting multiple invocations of test together with the && and || operators and parentheses. ===Exit status=== This command returns the following exit values: '''0''' - The Expression parameter is true '''1''' - The Expression parameter is false or missing '''>1''' - An error occurred ==Examples== 1. To test whether a file is nonexistent or empty, type: if test ! -s "$1" then echo $1 does not exist or is empty. fi If the file specified by the first positional parameter to the shell procedure, $1, does not exist or is of size 0, the test command displays the message. If $1 exists and has a size greater than 0, the test command displays nothing. Note: There must be a space between the -s function and the file name. The quotation marks around $1 ensure that the test works properly even if the value of $1 is a null string. If the quotation marks are omitted and $1 is the empty string, the test command displays the error message: test: argument expected. 2. To do a complex comparison, type: if [ "$#" -lt 2 ] || ! [ -e "$1" ] then exit fi If the shell procedure is given fewer than two positional parameters or the file specified by $1 does not exist, then the shell procedure exits. The special shell variable $# represents the number of positional parameters entered on the command line that starts this shell procedure. ==See also== * [List of POSIX commands](/source/List_of_POSIX_commands) * [Unix shell](/source/Unix_shell) * [find (Unix)](/source/find_(Unix)) ==References== {{Reflist}} ==Further reading== * {{cite book|last1=Robbins |first1=Arnold |author2=Nelson H. F. Beebe |title=Classic Shell Scripting: Hidden Commands that Unlock the Power of Unix |chapter-url=https://books.google.com/books?id=jO-iKwPRX0QC&pg=PA146 |date=2005 |publisher=O'Reilly Media, Inc. |isbn=978-0-596-55526-9 |pages=120–128 |chapter=6.2.4 The test Command}} * {{cite web |author=Ian Shields |date=20 February 2007 |title=Linux tip: Bash test and comparison functions |work=IBM DeveloperWorks |url=https://www.ibm.com/developerworks/library/l-bash-test/ }} * {{cite book |author=William Shotts |date=2013 |title=The Linux Command Line |chapter=27 – Flow Control: Branching With if |pages=381–390 |publisher=No Starch Press |isbn=978-1-59327-389-7 |url=http://linuxcommand.org/tlcl.php }} (free download) ==External links== {{Wikibooks|Guide to Unix|Commands}} * {{man|cu|test|SUS}} * {{man|1|test|die.net}} * {{man|1|test|Plan 9}} {{Unix commands}} {{Plan 9 commands}} {{Core Utilities commands}} Category:Unix SUS2008 utilities Category:Plan 9 commands Category:IBM i Qshell commands Category:Conditional constructs --- Adapted from the Wikipedia article [Test (Unix)](https://en.wikipedia.org/wiki/Test_(Unix)) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Test_(Unix)?action=history)). 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