test (Unix)

{{Infobox software

| name = test

| logo =

| screenshot =

| screenshot size =

| caption =

| developer = Various open-source and commercial developers

| released =

| other_names = [

| latest release version =

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| programming language = C

| operating system = Unix, Unix-like, Plan 9, IBM i

| platform = Cross-platform

| genre = Command

| license = coreutils: GPLv3+
Plan 9: MIT License

| website =

}}

test is a command-line utility found in Unix, Plan 9, and Unix-like operating systems that evaluates conditional expressions. test was turned into a shell builtin command in 1981 with UNIX System III and at the same time made available under the alternate name [.http://www.in-ulm.de/~mascheck/bourne/#system3 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, 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 compatible shells require a space between the program name and its arguments). One must test explicitly for file names in the C shell. File-name substitution (globbing) 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 coreutils was written by Kevin Braunsdorf and Matthew Bradburn.[https://manpages.debian.org/buster/coreutils/test.1.en.html test(1) — coreutils — Debian buster — Debian Manpages] The command is available as a separate package for Microsoft Windows as part of the UnxUtils collection of native Win32 ports of common GNU Unix-like utilities.{{Cite web|url=http://unxutils.sourceforge.net/|title=Native Win32 ports of some GNU utilities|website=unxutils.sourceforge.net}} The {{Mono|test}} command has also been ported to the IBM i operating system.{{cite web |title=IBM System i Version 7.2 Programming Qshell |language=en |author=IBM |website=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 }}

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.

Argument ! Returns `True` if the file
class="wikitable"
-b	is a block special file
-c	is a character special file
-d	is a directory
-e	exists
-f	is a regular file
-g	has the Set Group ID bit set
-h	is a symbolic link
-k	has the sticky bit set
-L	is a symbolic link
-p	is a named pipe (FIFO)
-r	is readable by the current process
-s	has a size greater than 0
-t	FileDescriptor is open and associated with a terminal
-u	has the Set User ID bit set
-w	has the write flag is on
-x	has execute 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]] 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 or hard link)

==String arguments==

In 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 algebraically 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[http://www.opengroup.org/onlinepubs/009695399/utilities/test.html IEEE Std 1003.1, 2004, documentation for test] 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.

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

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.