fish-shell/sphinx_doc_src/cmds/switch.rst

50 lines
1.6 KiB
ReStructuredText
Raw Normal View History

.. _cmd-switch:
switch - conditionally execute a block of commands
==================================================
Synopsis
--------
::
switch VALUE; [case [WILDCARD...]; [COMMANDS...]; ...] end
Description
-----------
``switch`` performs one of several blocks of commands, depending on whether a specified value equals one of several wildcarded values. ``case`` is used together with the ``switch`` statement in order to determine which block should be executed.
Each ``case`` command is given one or more parameters. The first ``case`` command with a parameter that matches the string specified in the switch command will be evaluated. ``case`` parameters may contain wildcards. These need to be escaped or quoted in order to avoid regular wildcard expansion using filenames.
Note that fish does not fall through on case statements. Only the first matching case is executed.
Note that command substitutions in a case statement will be evaluated even if its body is not taken. All substitutions, including command substitutions, must be performed before the value can be compared against the parameter.
Example
-------
If the variable \$animal contains the name of an animal, the following code would attempt to classify it:
2018-12-19 11:14:04 +08:00
::
switch $animal
case cat
echo evil
case wolf dog human moose dolphin whale
echo mammal
case duck goose albatross
echo bird
case shark trout stingray
echo fish
case '*'
echo I have no idea what a $animal is
end
If the above code was run with ``$animal`` set to ``whale``, the output
would be ``mammal``.