fish-shell/doc_src/switch.txt

\section switch switch - conditionally execute a block of commands

\subsection switch-synopsis Synopsis
<tt>switch VALUE; [case [WILDCARD...]; [COMMANDS...]; ...] end</tt>

\subsection switch-description Description

The \c switch statement is used to perform one of several blocks of
commands depending on whether a specified value equals one of several
wildcarded values. The \c case statement is used together with the \c
switch statement in order to determine which block should be
performed.

Each \c case command is given one or more parameter. The first \c case
command with a parameter that matches the string specified in the
switch command will be evaluated. \c 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. Though the
syntax may look a bit like C switch statements, it behaves more like
the case stamantes of traditional shells.

Also note that command substitutions in a case statement will be
evaluated even if it's body is not taken. This may seem
counterintuitive at first, but it is unavoidable, since it would be
impossible to know if a case command will evaluate to true before all
forms of parameter expansion have been performed for the case command.

\subsection switch-example Example

If the variable \$animal contains the name of an animal, the following
code would attempt to classify it:

<pre>
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
</pre>

If the above code was run with \c \$animal set to \c whale, the output
would be \c mammal.