Copyright (c) 2012 The NetBSD Foundation, Inc.
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by Christos Zoulas.
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.Dd November 2, 2012 .Dt FLOCK 1 .Os .Sh NAME .Nm flock .Nd Provide locking API for shell scripts .Sh SYNOPSIS .Nm .Op Fl dnosvx .Op Fl w Ar timeout .Ar lockfile|lockdir .Op Fl c Ar command | .Op Ar command ... .Nm .Op Fl dnsuvx .Op Fl w Ar timeout .Ar lockfd .Sh DESCRIPTION The .Nm utility provides .Xr flock 2 access to the command line or scripts. The first form locks a file or directory while the command provided is executed. If the file or directory does not exist, then a file is created.
p The second form can use an arbitrary file descriptor that is provided from a shell script for example: d -literal ( flock -s 100 # commands to be executed under the lock ) 100> /path/to/lockfile .Ed
p The following options are available: l -tag -width "XXXXXXXXXXXXXXXXX" t Fl c Ar command Pass a command to a the shell. t Fl d , Fl Fl debug Provide debugging output. t Fl n , Fl Fl nb , Fl Fl nonblock Don't block and fail immediately if the lock could not be obtained. t Fl o , Fl Fl close Close the file before executing the command. This is useful if the child forks and should not be holding the lock. t Fl s , Fl Fl shared Obtain a shared lock. t Fl u , Fl Fl unlock Unlock an existing lock. This is available only for a file descriptor. t Fl v , Fl Fl verbose On error print an explanation of the failure. t Fl w , Fl Fl wait , Fl Fl timeout Ar seconds Fail if the lock could not be obtained after .Ar seconds . t Fl x , Fl Fl exclusive Obtain an exclusive lock. .El .Sh EXIT STATUS .Ex -std .Sh SEE ALSO .Xr shlock 1 , .Xr flock 2 .Sh HISTORY An .Nm utility appeared in .Nx 6.1 .