while - perform a command multiple times¶
Synopsis¶
while CONDITION; COMMANDS...; end
Description¶
while
repeatedly executes CONDITION
, and if the exit status is 0, then executes COMMANDS
.
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.)
You can use and or or for complex conditions. Even more complex control can be achieved with while true
containing a break.
Example¶
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.