getlock is a command-line lockfile utility that uses 'fcntl' style locks, which release if the program exits. getlock normally locks one or more files and then runs a command, but it can be run without a command in order to just lock the files. It can also run a command if all the locks cannot be made, kill off current lock owners, write a PID to a lock file, and background, but still keep the lock, for use in shell scripts.
