FLOCK(1) BSD General Commands Manual FLOCK(1)
NAME
flock -- Provide locking API for shell scripts
SYNOPSIS
flock [-dnosvx] [-w timeout] lockfile|lockdir [-c command] | [command ...]
flock [-dnsuvx] [-w timeout] lockfd
DESCRIPTION
The flock utility provides flock(2) access to the command line or scripts. The first form locks a file or directory while the command pro-
vided is executed. If the file or directory does not exist, then a file is created.
The second form can use an arbitrary file descriptor that is provided from a shell script for example:
(
flock -s 100
# commands to be executed under the lock
) 100> /path/to/lockfile
The following options are available:
-c command Pass a command to a the shell.
-d, --debug Provide debugging output.
-n, --nb, --nonblock
Don't block and fail immediately if the lock could not be obtained.
-o, --close Close the file before executing the command. This is useful if the child forks and should not be holding the lock.
-s, --shared Obtain a shared lock.
-u, --unlock Unlock an existing lock. This is available only for a file descriptor.
-v, --verbose On error print an explanation of the failure.
-w, --wait, --timeout seconds
Fail if the lock could not be obtained after seconds.
-x, --exclusive Obtain an exclusive lock.
EXIT STATUS
The flock utility exits 0 on success, and >0 if an error occurs.
SEE ALSO
shlock(1), flock(2)
HISTORY
An flock utility appeared in NetBSD 6.1.
BSD
November 2, 2012 BSD
