test

test(1)                              fish                              test(1)



NAME
       test - perform tests on files and text

   Synopsis
       test [EXPRESSION]
       [ [EXPRESSION] ]

   Description
       Tests the expression given and sets the exit status to 0 if true, and 1
       if false. An expression is made up of one or more operators and their
       arguments.

       The first form (test) is preferred. For compatibility with other
       shells, the second form is available: a matching pair of square
       brackets ([ [EXPRESSION ] ]).

       This test is mostly POSIX-compatible.

       When using a variable as an argument for a test operator you should
       almost always enclose it in double-quotes. There are only two
       situations it is safe to omit the quote marks. The first is when the
       argument is a literal string with no whitespace or other characters
       special to the shell (e.g., semicolon). For example, test -b /my/file.
       The second is using a variable that expands to exactly one element
       including if that element is the empty string (e.g., `set x ''). If the
       variable is not set, set but with no value, or set to more than one
       value you must enclose it in double-quotes. For example,test '$x' =
       '$y'. Since it is always safe to enclose variables in double-quotes
       when used astest` arguments that is the recommended practice.

   Operators for files and directories
       · -b FILE returns true if FILE is a block device.

       · -c FILE returns true if FILE is a character device.

       · -d FILE returns true if FILE is a directory.

       · -e FILE returns true if FILE exists.

       · -f FILE returns true if FILE is a regular file.

       · -g FILE returns true if FILE has the set-group-ID bit set.

       · -G FILE returns true if FILE exists and has the same group ID as the
         current user.

       · -k FILE returns true if FILE has the sticky bit set. If the OS does
         not support the concept it returns false. See
         https://en.wikipedia.org/wiki/Sticky_bit.

       · -L FILE returns true if FILE is a symbolic link.

       · -O FILE returns true if FILE exists and is owned by the current user.

       · -p FILE returns true if FILE is a named pipe.

       · -r FILE returns true if FILE is marked as readable.

       · -s FILE returns true if the size of FILE is greater than zero.

       · -S FILE returns true if FILE is a socket.

       · -t FD returns true if the file descriptor FD is a terminal (TTY).

       · -u FILE returns true if FILE has the set-user-ID bit set.

       · -w FILE returns true if FILE is marked as writable; note that this
         does not check if the filesystem is read-only.

       · -x FILE returns true if FILE is marked as executable.

   Operators for text strings
       · STRING1 = STRING2 returns true if the strings STRING1 and STRING2 are
         identical.

       · STRING1 != STRING2 returns true if the strings STRING1 and STRING2
         are not identical.

       · -n STRING returns true if the length of STRING is non-zero.

       · -z STRING returns true if the length of STRING is zero.

   Operators to compare and examine numbers
       · NUM1 -eq NUM2 returns true if NUM1 and NUM2 are numerically equal.

       · NUM1 -ne NUM2 returns true if NUM1 and NUM2 are not numerically
         equal.

       · NUM1 -gt NUM2 returns true if NUM1 is greater than NUM2.

       · NUM1 -ge NUM2 returns true if NUM1 is greater than or equal to NUM2.

       · NUM1 -lt NUM2 returns true if NUM1 is less than NUM2.

       · NUM1 -le NUM2 returns true if NUM1 is less than or equal to NUM2.

       Both integers and floating point numbers are supported.

   Operators to combine expressions
       · COND1 -a COND2 returns true if both COND1 and COND2 are true.

       · COND1 -o COND2 returns true if either COND1 or COND2 are true.

       Expressions can be inverted using the ! operator:

       · ! EXPRESSION returns true if EXPRESSION is false, and false if
         EXPRESSION is true.

       Expressions can be grouped using parentheses.

       · ( EXPRESSION ) returns the value of EXPRESSION.

       Note that parentheses will usually require escaping with \( to avoid
       being interpreted as a command substitution.

   Examples
       If the /tmp directory exists, copy the /etc/motd file to it:

       if test -d /tmp
           cp /etc/motd /tmp/motd
       end

       If the variable MANPATH is defined and not empty, print the contents.
       (If MANPATH is not defined, then it will expand to zero arguments,
       unless quoted.)

       if test -n '$MANPATH'
           echo $MANPATH
       end

       Parentheses and the -o and -a operators can be combined to produce more
       complicated expressions. In this example, success is printed if there
       is a /foo or /bar file as well as a /baz or /bat file.

       if test \( -f /foo -o -f /bar \) -a \( -f /baz -o -f /bat \)
           echo Success.
       end.

       Numerical comparisons will simply fail if one of the operands is not a
       number:

       if test 42 -eq 'The answer to life, the universe and everything'
           echo So long and thanks for all the fish  # will not be executed
       end

       A common comparison is with $status:

       if test $status -eq 0
           echo 'Previous command succeeded'
       end

       The previous test can likewise be inverted:

       if test ! $status -eq 0
           echo 'Previous command failed'
       end

       which is logically equivalent to the following:

       if test $status -ne 0
           echo 'Previous command failed'
       end

   Standards
       test implements a subset of the IEEE Std 1003.1-2008 (POSIX.1)
       standard. The following exceptions apply:

       · The < and > operators for comparing strings are not implemented.

       · Because this test is a shell builtin and not a standalone utility,
         using the -c flag on a special file descriptors like standard input
         and output may not return the same result when invoked from within a
         pipe as one would expect when invoking the test utility in another
         shell.

       In cases such as this, one can use command test to explicitly use the
       system's standalone test rather than this builtin test.

Version 3.0.2                   Tue Mar 26 2019                        test(1)