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\section if if - conditionally execute a command
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\subsection if-synopsis Synopsis
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<tt>if CONDITION; COMMANDS_TRUE...; [else; COMMANDS_FALSE...;] end</tt>
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\subsection if-description Description
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<tt>if</tt> will execute the command CONDITION. If the condition's
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exit status is 0, the commands COMMANDS_TRUE will execute. If the
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exit status is not 0 and <tt>else</tt> is given, COMMANDS_FALSE will
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be executed.
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In order to use the exit status of multiple commands as the condition
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of an if block, use <a href="#begin"><tt>begin; ...; end</tt></a> and
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the short circuit commands <a href="commands.html#and">and</a> and <a
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href="commands.html#or">or</a>.
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The exit status of the last foreground command to exit can always be
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accessed using the <a href="index.html#variables-status">$status</a>
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variable.
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\subsection if-example Example
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<pre>
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if test -f foo.txt
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echo foo.txt exists
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else
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echo foo.txt does not exist
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end
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</pre>
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will print <tt>foo.txt exists</tt> if the file foo.txt
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exists and is a regular file, otherwise it will print
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<tt>foo.txt does not exist</tt>.
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