flock (1)            - manage locks from shell scripts
flock (2)            - apply or remove an advisory lock on an open file
flock_lock_inode_wait (9) - Apply a FLOCK-style lock to a file
flockfile (3)        - lock FILE for stdio
Mail::Box::Locker::Flock (3pm) - lock a folder using kernel file-locking
sys_flock (9)        - flock system call.