DOKK / manpages / debian 10 / sn / snlockf.8.en
lockf(8) System Manager's Manual lockf(8)

lockf - lock files from within shell-scripts (used by sn news system)

lockf

lockf can be used to lock files from within shell-scripts. Filedescriptor 3 is always locked, and the lock remains until the process is killed. The process-id is written to standard output, as to facilitate killing the process.

It is used by the sn news system.

sn(8)