while - perform a command multiple times¶
while CONDITION; COMMANDS...; end
while repeatedly executes
CONDITION, and if the exit status is 0, then executes
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.)
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.