\section while while - perform a command multiple times
\subsection while-synopsis Synopsis
\fish{synopsis}
while CONDITION; COMMANDS...; end
\endfish
\subsection while-description Description
`while` repeatedly executes `CONDITION`, and if the exit status is 0, then executes `COMMANDS`.
If the exit status of `CONDITION` is non-zero on the first iteration, `COMMANDS` will not be executed at all.
You can use `and` or `or` for complex conditions. Even more complex control can be achieved with `while true` containing a break.
\subsection while-example Example
\fish
while test -f foo.txt; or test -f bar.txt ; echo file exists; sleep 10; end
# outputs 'file exists' at 10 second intervals as long as the file foo.txt or bar.txt exists.
\endfish