$ setlock -h
Usage of setlock:
-N (Default.) Delay. If fn is locked by another process, setlock waits until it can obtain a new lock.
-V Show version verbosely.
-X (Default.) If fn cannot be opened (or created) or locked, setlock prints an error message and exits nonzero.
-n No delay. If fn is locked by another process, setlock gives up.
-v Show version.
-x If fn cannot be opened (or created) or locked, setlock exits zero.