fish-shell/doc_src/cmds/for.rst
Aaron Gyes af61ea1325 doc_src: Continue the slog through the letter F.
We are using only :: in a synopsis for fishscript examples given
of the command being documented.
2021-12-17 15:16:47 -08:00

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.. _cmd-for:
for - perform a set of commands multiple times
==============================================
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.
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.