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52 lines
1.8 KiB
Text
52 lines
1.8 KiB
Text
\section switch switch - conditionally execute a block of commands
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\subsection switch-synopsis Synopsis
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<tt>switch VALUE; [case [WILDCARD...]; [COMMANDS...]; ...] end</tt>
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\subsection switch-description Description
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The \c switch statement is used to perform one of several blocks of
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commands depending on whether a specified value equals one of several
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wildcarded values. The \c case statement is used together with the \c
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switch statement in order to determine which block should be
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performed.
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Each \c case command is given one or more parameter. The first \c case
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command with a parameter that matches the string specified in the
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switch command will be evaluated. \c case parameters may contain
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wildcards. These need to be escaped or quoted in order to avoid
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regular wildcard expansion using filenames.
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Note that fish does not fall through on case statements. Though the
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syntax may look a bit like C switch statements, it behaves more like
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the case stamantes of traditional shells.
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Also note that command substitutions in a case statement will be
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evaluated even if it's body is not taken. This may seem
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counterintuitive at first, but it is unavoidable, since it would be
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impossible to know if a case command will evaluate to true before all
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forms of parameter expansion have been performed for the case command.
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\subsection switch-example Example
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If the variable \$animal contains the name of an animal, the following
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code would attempt to classify it:
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<pre>
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switch $animal
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case cat
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echo evil
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case wolf dog human moose dolphin whale
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echo mammal
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case duck goose albatross
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echo bird
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case shark trout stingray
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echo fish
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case '*'
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echo I have no idea what a $animal is
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end
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</pre>
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If the above code was run with \c \$animal set to \c whale, the output
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would be \c mammal.
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