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Dd October 4, 2019
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 file Ns \^|\^ Ns Ar directory
Ar command
Op Ar args No ...
\"
Nm
Op Fl dnosvx
Op Fl w Ar timeout
Ar file Ns \^|\^ Ns Ar directory
Fl c Ar command
\"
Nm
Op Fl dnsuvx
Op Fl w Ar timeout
Ar number
Sh DESCRIPTION
The
Nm
utility provides
Xr flock 2
access to the command line or scripts.
The first two forms lock the specified
Ar file
or
Ar directory
while the provided command is executed.
If the path does not exist, then a file of that name is created with
mode 0600.
Pp
The third form can use an arbitrary file descriptor
Ar number
that is provided from a shell script for example:
Bd -literal -offset indent
(
       flock -s 100
       # commands to be executed under the lock
) 100> /path/to/lockfile
Ed
Pp
The following options are available:
Bl -tag -width Fl
It Fl c Ar command
Pass a command to a the shell.
It Fl d , Fl Fl debug
Provide debugging output.
It Fl n , Fl Fl nb , Fl Fl nonblock
Don't block and fail immediately if the lock could not be obtained.
It 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.
It Fl s , Fl Fl shared
Obtain a shared lock.
It Fl u , Fl Fl unlock
Unlock an existing lock.
This is available only for a file descriptor.
It Fl v , Fl Fl verbose
On error print an explanation of the failure.
It Fl w , Fl Fl wait , Fl Fl timeout Ar seconds
Fail if the lock could not be obtained after
Ar seconds .
It Fl x , Fl Fl exclusive
Obtain an exclusive lock.
This is the default.
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 .

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