xref: /netbsd-src/usr.bin/flock/flock.1 (revision 5e583655578fff99c64cac3256579bc08228d612)

.\"	$NetBSD: flock.1,v 1.13 2019/10/04 16:14:05 uwe Exp $
.\"
.\" Copyright (c) 2012 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Christos Zoulas.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
.\" PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
.\"
.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 .