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FLOCK(1) NetBSD General Commands Manual FLOCK(1)
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flock -- Provide locking API for shell scripts
flock [-dnosvx] [-w timeout] lockfile|lockdir [-c command] |
flock [-dnsuvx] [-w timeout] lockfd
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
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
-o, --close Close the file before executing the command. This is
useful if the child forks and should not be holding
-s, --shared Obtain a shared lock.
-u, --unlock Unlock an existing lock. This is available only for a
-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. This is the default.
The flock utility exits 0 on success, and >0 if an error occurs.
An flock utility appeared in NetBSD 6.1.
NetBSD 9.2 August 18, 2014 NetBSD 9.2