rlock creates NFS safe lockfiles. it can optionally run a program while holding
the lock, ensuring lockfile removal on program exit. if a program is specified
to be run rlock will spawn a background thread to kept the lockfile 'fresh' by
touching it at a regular interval. in this way a lease is maintained on the
lockfile and other processes attempting to obtain the lock can determine that it
is in use.

WWW: https://github.com/ahoward/lockfile