fish-shell/sphinx_doc_src/cmds/if.rst

52 lines
1.4 KiB
ReStructuredText

.. _cmd-if:
if - conditionally execute a command
====================================
Synopsis
--------
::
if CONDITION; COMMANDS_TRUE...;
[else if CONDITION2; COMMANDS_TRUE2...;]
[else; COMMANDS_FALSE...;]
end
Description
-----------
``if`` will execute the command ``CONDITION``. If the condition's exit status is 0, the commands ``COMMANDS_TRUE`` will execute. If the exit status is not 0 and :ref:`else <cmd-else>` is given, ``COMMANDS_FALSE`` will be executed.
You can use :ref:`and <cmd-and>` or :ref:`or <cmd-or>` in the condition. See the second example below.
The exit status of the last foreground command to exit can always be accessed using the :ref:`$status <variables-status>` variable.
Example
-------
The following code will print ``foo.txt exists`` if the file foo.txt exists and is a regular file, otherwise it will print ``bar.txt exists`` if the file bar.txt exists and is a regular file, otherwise it will print ``foo.txt and bar.txt do not exist``.
::
if test -f foo.txt
echo foo.txt exists
else if test -f bar.txt
echo bar.txt exists
else
echo foo.txt and bar.txt do not exist
end
The following code will print "foo.txt exists and is readable" if foo.txt is a regular file and readable
::
if test -f foo.txt
and test -r foo.txt
echo "foo.txt exists and is readable"
end