test - perform tests on files and text¶

Synopsis¶

test [EXPRESSION]
[ [EXPRESSION] ]

Description¶

test checks the given conditions and sets the exit status to 0 if they are true, 1 if they are false.

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

When using a variable or command substitution as an argument with test you should almost always enclose it in double-quotes, as variables expanding to zero or more than one argument will most likely interact badly with test.

Warning

For historical reasons, test supports the one-argument form (test foo), and this will also be triggered by e.g. test -n $foo if $foo is unset. We recommend you don’t use the one-argument form and quote all variables or command substitutions used with test.

This confusing misfeature will be removed in future. test -n without any additional argument will be false, test -z will be true and any other invocation with exactly one or zero arguments, including test -d and test "foo" will be an error.

The same goes for [, e.g. [ "foo" ] and [ -d ] will be errors.

This can be turned on already via the test-require-arg feature flag, and will eventually become the default and then only option.

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 to compare files and directories¶

FILE1 -nt FILE2: Returns true if FILE1 is newer than FILE2, or FILE1 exists and FILE2 does not.
FILE1 -ot FILE2: Returns true if FILE1 is older than FILE2, or FILE2 exists and FILE1 does not.
FILE1 -ef FILE1: Returns true if FILE1 and FILE2 refer to the same file.

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 \ (so they appear as $ and $) 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

Be careful with unquoted variables:

if test -n $MANPATH
    # This will also be reached if $MANPATH is unset,
    # because in that case we have `test -n`, so it checks if "-n" is non-empty, and it is.
    echo $MANPATH
end

This will change in a future release of fish, or already with the test-require-arg feature flag - if $MANPATH is unset, if test -n $MANPATH will be false.

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¶

Unlike many things in fish, 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.
With test-require-arg, the zero- and one-argument modes will behave differently.

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

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