sfre (system flight recorder editor) is a script that wraps a text editor or any arbitrary command and implements logging, file locking, and change tracking for the command executed. It is meant for helping system administrators manage a system in tandem without interfering with each other.
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.
Safelock is a file-based locking primitive that provides mutual exclusion between unrelated processes and threads. It offers advantages over POSIX and BSD file locks such as: compatibility with multi-threaded applications, support for lock attempt timeouts, detection of crashed lock holders, and detailed lock status (PID, lock age, custom data).