.. _cmd-test: test - perform tests on files and text ====================================== Synopsis -------- .. synopsis:: test [EXPRESSION] [ [EXPRESSION] ] Description ----------- .. only:: builder_man NOTE: This page documents the fish builtin ``test``. To see the documentation on the ``test`` command you might have, use ``command man test``. 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 as ``test`` 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 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 ``\(`` 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 :envvar:`MANPATH` is defined and not empty, print the contents. (If :envvar:`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 :envvar:`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``.