freebsd-dev/usr.sbin/daemon/daemon.8

.\" Copyright (c) 1999 Berkeley Software Design, Inc. All rights reserved.
.\"
.\" 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.
.\" 3. Berkeley Software Design Inc's name may not be used to endorse or
.\"    promote products derived from this software without specific prior
.\"    written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``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 BERKELEY SOFTWARE DESIGN INC 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.
.\"
.\" $FreeBSD$
.\"
.Dd June 4, 2012
.Dt DAEMON 8
.Os
.Sh NAME
.Nm daemon
.Nd run detached from the controlling terminal
.Sh SYNOPSIS
.Nm
.Op Fl cfr
.Op Fl p Ar pidfile
.Op Fl u Ar user
.Ar command arguments ...
.Sh DESCRIPTION
The
.Nm
utility detaches itself from the controlling terminal and
executes the program specified by its arguments.
Privileges may be lowered to the specified user.
.Pp
The options are as follows:
.Bl -tag -width indent
.It Fl c
Change the current working directory to the root
.Pq Dq Pa / .
.It Fl f
Redirect standard input, standard output and standard error to
.Pa /dev/null .
.It Fl p Ar file
Write the ID of the created process into the
.Ar file
using the
.Xr pidfile 3
functionality.
The program is executed in a spawned child process while the
.Nm
waits until it terminates to keep the
.Ar file
locked and removes it after the process exits.
The
.Ar file
owner is the user who runs the
.Nm
regardless of whether the
.Fl u
option is used or not.
.It Fl r
Supervise and restart the program if it has been terminated.
.It Fl u Ar user
Login name of the user to execute the program under.
Requires adequate superuser privileges.
.El
.Pp
If the
.Fl p
or
.Fl r
option is specified the program is executed in a spawned child process.
The
.Nm
waits until it terminates to keep the pid file locked and removes it
after the process exits or restarts the program.
In this case if the monitoring
.Nm
receives software termination signal (SIGTERM) it forwards it to the
spawned process.
Normally it will cause the child to exit followed by the termination
of the supervising process after removing the pidfile.
.Sh EXIT STATUS
The
.Nm
utility exits 1 if an error is returned by the
.Xr daemon 3
library routine, 2 if the
.Ar pidfile
is requested, but cannot be opened, 3 if process is already running (pidfile
exists and is locked),
otherwise 0.
.Sh DIAGNOSTICS
If the command cannot be executed, an error message is displayed on
standard error unless the
.Fl f
flag is specified.
.Sh SEE ALSO
.Xr setregid 2 ,
.Xr setreuid 2 ,
.Xr daemon 3 ,
.Xr exec 3 ,
.Xr pidfile 3 ,
.Xr termios 4 ,
.Xr tty 4
.Sh HISTORY
The
.Nm
utility first appeared in
.Fx 4.7 .
Add a new utility that runs an executable detached from the controlling terminal. Discussed on: -hackers Obtained from: BSD/OS 2001-08-30 04:48:02 +00:00			`.\" Copyright (c) 1999 Berkeley Software Design, Inc. All rights reserved.`
			`.\"`
			`.\" 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.`
			`.\" 3. Berkeley Software Design Inc's name may not be used to endorse or`
			`.\" promote products derived from this software without specific prior`
			`.\" written permission.`
			`.\"`
			.\" THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``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 BERKELEY SOFTWARE DESIGN INC 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.`
			`.\"`
			`.\" $FreeBSD$`
			`.\"`
Document -r option in SYNOPSIS and usage statement. Submitted by: Andrey Zonov <andrey zonov.org> MFC after: 3 days 2012-06-04 09:25:01 +00:00			`.Dd June 4, 2012`
Add a new utility that runs an executable detached from the controlling terminal. Discussed on: -hackers Obtained from: BSD/OS 2001-08-30 04:48:02 +00:00			`.Dt DAEMON 8`
mdoc(7) police: minor formatting tweaks. 2001-08-31 12:52:50 +00:00			`.Os`
Add a new utility that runs an executable detached from the controlling terminal. Discussed on: -hackers Obtained from: BSD/OS 2001-08-30 04:48:02 +00:00			`.Sh NAME`
			`.Nm daemon`
			`.Nd run detached from the controlling terminal`
			`.Sh SYNOPSIS`
mdoc(7) police: minor formatting tweaks. 2001-08-31 12:52:50 +00:00			`.Nm`
Document -r option in SYNOPSIS and usage statement. Submitted by: Andrey Zonov <andrey zonov.org> MFC after: 3 days 2012-06-04 09:25:01 +00:00			`.Op Fl cfr`
Give daemon(8) the ability to create a pid-file. Since the target program does not know anything about the pid-file and we don't keep a babysitting process for the task, the pid-file will linger. Submitted by: mi PR: 56398 2004-06-02 06:48:13 +00:00			`.Op Fl p Ar pidfile`
Improve previous commit by using setusercontext(3) and removing the group option. Bump doc date for manual page changes. Reviewed by: rwatson, ru, will (older version) 2007-03-19 12:12:53 +00:00			`.Op Fl u Ar user`
mdoc(7) police: minor formatting tweaks. 2001-08-31 12:52:50 +00:00			`.Ar command arguments ...`
Add a new utility that runs an executable detached from the controlling terminal. Discussed on: -hackers Obtained from: BSD/OS 2001-08-30 04:48:02 +00:00			`.Sh DESCRIPTION`
			`The`
			`.Nm`
mdoc(7) police: minor formatting tweaks. 2001-08-31 12:52:50 +00:00			`utility detaches itself from the controlling terminal and`
Add a new utility that runs an executable detached from the controlling terminal. Discussed on: -hackers Obtained from: BSD/OS 2001-08-30 04:48:02 +00:00			`executes the program specified by its arguments.`
Improve previous commit by using setusercontext(3) and removing the group option. Bump doc date for manual page changes. Reviewed by: rwatson, ru, will (older version) 2007-03-19 12:12:53 +00:00			`Privileges may be lowered to the specified user.`
Add a new utility that runs an executable detached from the controlling terminal. Discussed on: -hackers Obtained from: BSD/OS 2001-08-30 04:48:02 +00:00			`.Pp`
			`The options are as follows:`
mdoc(7) police: minor formatting tweaks. 2001-08-31 12:52:50 +00:00			`.Bl -tag -width indent`
Add a new utility that runs an executable detached from the controlling terminal. Discussed on: -hackers Obtained from: BSD/OS 2001-08-30 04:48:02 +00:00			`.It Fl c`
mdoc(7) police: minor formatting tweaks. 2001-08-31 12:52:50 +00:00			`Change the current working directory to the root`
			`.Pq Dq Pa / .`
Add a new utility that runs an executable detached from the controlling terminal. Discussed on: -hackers Obtained from: BSD/OS 2001-08-30 04:48:02 +00:00			`.It Fl f`
			`Redirect standard input, standard output and standard error to`
			`.Pa /dev/null .`
Give daemon(8) the ability to create a pid-file. Since the target program does not know anything about the pid-file and we don't keep a babysitting process for the task, the pid-file will linger. Submitted by: mi PR: 56398 2004-06-02 06:48:13 +00:00			`.It Fl p Ar file`
mdoc(7) fixes. 2004-07-07 19:57:16 +00:00			`Write the ID of the created process into the`
Teach daemon(8) how to use pidfile(3). 2005-08-24 17:24:39 +00:00			`.Ar file`
Improve previous commit by using setusercontext(3) and removing the group option. Bump doc date for manual page changes. Reviewed by: rwatson, ru, will (older version) 2007-03-19 12:12:53 +00:00			`using the`
Teach daemon(8) how to use pidfile(3). 2005-08-24 17:24:39 +00:00			`.Xr pidfile 3`
			`functionality.`
The pidfile_open(3) is going to be fixed to set close-on-exec in order not to leak the descriptor after exec(3). This raises the issue for daemon(3) of the pidfile lock to be lost when the child process executes. To solve this and also to have the pidfile cleaned up when the program exits, if a pidfile is specified, spawn a child to exec the command and wait in the parent keeping the pidfile locked until the child process exits and remove the file. Reported by: Andrey Zonov <andrey zonov org> Suggested by: pjd Reviewed by: pjd MFC after: 2 weeks 2012-02-19 10:20:37 +00:00			`The program is executed in a spawned child process while the`
			`.Nm`
			`waits until it terminates to keep the`
			`.Ar file`
			`locked and removes it after the process exits.`
			`The`
			`.Ar file`
			`owner is the user who runs the`
			`.Nm`
			`regardless of whether the`
Revert 229667: After some discussion of this change, it seems it is better to leave the pidfile open where it was. Add a note to the man page describing pidfile strategies to use if the daemon is to be run as a user other than root. 2012-01-25 14:50:12 +00:00			`.Fl u`
The pidfile_open(3) is going to be fixed to set close-on-exec in order not to leak the descriptor after exec(3). This raises the issue for daemon(3) of the pidfile lock to be lost when the child process executes. To solve this and also to have the pidfile cleaned up when the program exits, if a pidfile is specified, spawn a child to exec the command and wait in the parent keeping the pidfile locked until the child process exits and remove the file. Reported by: Andrey Zonov <andrey zonov org> Suggested by: pjd Reviewed by: pjd MFC after: 2 weeks 2012-02-19 10:20:37 +00:00			`option is used or not.`
Add -r option to restart the program if it has been terminated. Suggested by: Andrey Zonov <andrey zonov org> MFC after: 2 weeks 2012-02-19 10:36:29 +00:00			`.It Fl r`
			`Supervise and restart the program if it has been terminated.`
			`.It Fl u Ar user`
			`Login name of the user to execute the program under.`
			`Requires adequate superuser privileges.`
			`.El`
			`.Pp`
			`If the`
			`.Fl p`
			`or`
			`.Fl r`
			`option is specified the program is executed in a spawned child process.`
			`The`
			`.Nm`
			`waits until it terminates to keep the pid file locked and removes it`
			`after the process exits or restarts the program.`
			`In this case if the monitoring`
If the supervising process receives SIGTERM, forward it to the spawned process. Normally it will cause the child to exit followed by the termination of the supervisor after removing the pidfile. This looks like desirable behavior, because termination of a supervisor usually supposes termination of its charge. Also it will fix the issue with stale pid files after reboot due to init kills a supervisor before its child exits. MFC after: 2 weeks 2012-02-19 10:23:51 +00:00			`.Nm`
			`receives software termination signal (SIGTERM) it forwards it to the`
			`spawned process.`
			`Normally it will cause the child to exit followed by the termination`
			`of the supervising process after removing the pidfile.`
Added the EXIT STATUS section where appropriate. 2005-01-17 07:44:44 +00:00			`.Sh EXIT STATUS`
Add a new utility that runs an executable detached from the controlling terminal. Discussed on: -hackers Obtained from: BSD/OS 2001-08-30 04:48:02 +00:00			`The`
			`.Nm`
			`utility exits 1 if an error is returned by the`
			`.Xr daemon 3`
mdoc(7) fixes. 2004-07-07 19:57:16 +00:00			`library routine, 2 if the`
			`.Ar pidfile`
Teach daemon(8) how to use pidfile(3). 2005-08-24 17:24:39 +00:00			`is requested, but cannot be opened, 3 if process is already running (pidfile`
			`exists and is locked),`
Give daemon(8) the ability to create a pid-file. Since the target program does not know anything about the pid-file and we don't keep a babysitting process for the task, the pid-file will linger. Submitted by: mi PR: 56398 2004-06-02 06:48:13 +00:00			`otherwise 0.`
Added the EXIT STATUS section where appropriate. 2005-01-17 07:44:44 +00:00			`.Sh DIAGNOSTICS`
Add a new utility that runs an executable detached from the controlling terminal. Discussed on: -hackers Obtained from: BSD/OS 2001-08-30 04:48:02 +00:00			`If the command cannot be executed, an error message is displayed on`
			`standard error unless the`
			`.Fl f`
			`flag is specified.`
			`.Sh SEE ALSO`
Add support for dropping privileges to a specified user and/or group. PR: 108523 Submitted by: Dmitri Alenitchev <dmitri@dworlds.ru> (original version) Reviewed by: mpp (first reply to PR) 2007-03-09 09:33:19 +00:00			`.Xr setregid 2 ,`
			`.Xr setreuid 2 ,`
Add a new utility that runs an executable detached from the controlling terminal. Discussed on: -hackers Obtained from: BSD/OS 2001-08-30 04:48:02 +00:00			`.Xr daemon 3 ,`
			`.Xr exec 3 ,`
Teach daemon(8) how to use pidfile(3). 2005-08-24 17:24:39 +00:00			`.Xr pidfile 3 ,`
Add a new utility that runs an executable detached from the controlling terminal. Discussed on: -hackers Obtained from: BSD/OS 2001-08-30 04:48:02 +00:00			`.Xr termios 4 ,`
			`.Xr tty 4`
			`.Sh HISTORY`
			`The`
			`.Nm`
			`utility first appeared in`
MFS: 1.2.2.2 2003-02-05 19:16:18 +00:00			`.Fx 4.7 .`