fish-shell/doc_src/cmds/for.rst
David Adam 3a23fdf359 docs: omnibus cleanup
Includes harmonizing the display of options and arguments, standardising
terminology, using the envvar directive more broadly, adding help options to all
commands that support them, simplifying some language, and tidying up multiple
formatting issues.

string documentation is not changed.
2022-03-12 00:21:13 +08:00

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.. _cmd-for:
for - perform a set of commands multiple times
==============================================
Synopsis
--------
.. synopsis::
for VARNAME in [VALUES ...]; COMMANDS ...; end
Description
-----------
**for** is a loop construct. It will perform the commands specified by *COMMANDS* multiple times. On each iteration, the local variable specified by *VARNAME* is assigned a new value from *VALUES*. If *VALUES* is empty, *COMMANDS* will not be executed at all. The *VARNAME* is visible when the loop terminates and will contain the last value assigned to it. If *VARNAME* does not already exist it will be set in the local scope. For our purposes if the **for** block is inside a function there must be a local variable with the same name. If the **for** block is not nested inside a function then global and universal variables of the same name will be used if they exist.
Much like :ref:`set <cmd-set>`, **for** does not modify $status, but the evaluation of its subordinate commands can.
The **-h** or **--help** option displays help about using this command.
Example
-------
::
for i in foo bar baz; echo $i; end
# would output:
foo
bar
baz
Notes
-----
The ``VARNAME`` was local to the for block in releases prior to 3.0.0. This means that if you did something like this:
::
for var in a b c
if break_from_loop
break
end
end
echo $var
The last value assigned to ``var`` when the loop terminated would not be available outside the loop. What ``echo $var`` would write depended on what it was set to before the loop was run. Likely nothing.