\section while while - perform a command multiple times

\subsection while-synopsis Synopsis
<tt>while CONDITION; COMMANDS...; end</tt>

\subsection while-description Description
The <tt>while</tt> builtin causes fish to continually execute CONDITION and
execute COMMANDS as long as CONDITION returned with status 0. If CONDITION is
false on the first time, COMMANDS will not be executed at all. Hints: use
<a href="#begin"><tt>begin; ...; end</tt></a> for complex conditions; more
complex control can be achieved with <tt>while true</tt> containing a
<a href="#break">break</a>.

\subsection while-example Example

<tt>while test -f foo.txt; echo file exists; sleep 10; end</tt>

causes fish to print the line 'file exists' at 10 second intervals as long as
the file foo.txt exists.