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28 lines
888 B
ReStructuredText
28 lines
888 B
ReStructuredText
.. _cmd-while:
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while - perform a set of commands multiple times
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================================================
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Synopsis
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--------
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**while** *CONDITION*; *COMMANDS...*; **end**
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Description
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-----------
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**while** repeatedly executes ``CONDITION``, and if the exit status is 0, then executes ``COMMANDS``.
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The exit status of the **while** loop is the exit status of the last iteration of the ``COMMANDS`` executed, or 0 if none were executed. (This matches other shells and is POSIX-compatible.)
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You can use :ref:`and <cmd-and>` or :ref:`or <cmd-or>` for complex conditions. Even more complex control can be achieved with ``while true`` containing a :ref:`break <cmd-break>`.
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Example
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-------
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::
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while test -f foo.txt; or test -f bar.txt ; echo file exists; sleep 10; end
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# outputs 'file exists' at 10 second intervals,
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# as long as the file foo.txt or bar.txt exists.
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