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freebsd-nq/lib/libc/gen/daemon.3

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BSD 4.4 Lite Lib Sources
1994-05-27 05:00:24 +00:00
.\" Copyright (c) 1993
.\" The Regents of the University of California. 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.
Renumber copyright clause 4 Renumber cluase 4 to 3, per what everybody else did when BSD granted them permission to remove clause 3. My insistance on keeping the same numbering for legal reasons is too pedantic, so give up on that point. Submitted by: Jan Schaumann <jschauma@stevens.edu> Pull Request: https://github.com/freebsd/freebsd/pull/96
2017-02-28 23:42:47 +00:00
.\" 3. Neither the name of the University nor the names of its contributors
BSD 4.4 Lite Lib Sources
1994-05-27 05:00:24 +00:00
.\" may be used to endorse or promote products derived from this software
.\" without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
.\"
.\" @(#)daemon.3 8.1 (Berkeley) 6/9/93
$Id$ -> $FreeBSD$
1999-08-28 00:22:10 +00:00
.\" $FreeBSD$
Add $Id$, to make it simpler for members of the translation teams to track. The $Id$ line is normally at the bottom of the main comment block in the man page, separated from the rest of the manpage by an empty comment, like so; .\" $Id$ .\" If the immediately preceding comment is a @(#) format ID marker than the the $Id$ will line up underneath it with no intervening blank lines. Otherwise, an additional blank line is inserted. Approved by: bde
1999-07-12 20:50:10 +00:00
.\"
Introduce the daemonfd function. The daemonfd function is equivalent to the daemon(3) function expect that arguments are descriptors. For example dhclient(8) which is sandboxed is unable to open /dev/null to close stdio instead it's allows to fail daemon(3) function to close the descriptors and then do it explicit in code. Instead of such hacks we can use now daemonfd. This API can be also helpful to migrate system to platforms like CheriBSD. Reviewed by: brooks@, bcr@, jilles@ (earlier version) Differential Revision: https://reviews.freebsd.org/D13433
2017-12-23 18:07:43 +00:00
.Dd December 23, 2017
BSD 4.4 Lite Lib Sources
1994-05-27 05:00:24 +00:00
.Dt DAEMON 3
.Os
.Sh NAME
.Nm daemon
.Nd run in the background
Introduce ".Lb" macro to libc manpages. More libraries manpages updates following.
2000-04-21 09:42:15 +00:00
.Sh LIBRARY
.Lb libc
BSD 4.4 Lite Lib Sources
1994-05-27 05:00:24 +00:00
.Sh SYNOPSIS
mdoc(7) police: Use the new .In macro for #include statements.
2001-10-01 16:09:29 +00:00
.In stdlib.h
Specify that daemon(3) returns int, and standardise the phrasing in the ERRORS section a bit, as well as now specifying the return status.
1996-06-22 23:46:00 +00:00
.Ft int
BSD 4.4 Lite Lib Sources
1994-05-27 05:00:24 +00:00
.Fn daemon "int nochdir" "int noclose"
Introduce the daemonfd function. The daemonfd function is equivalent to the daemon(3) function expect that arguments are descriptors. For example dhclient(8) which is sandboxed is unable to open /dev/null to close stdio instead it's allows to fail daemon(3) function to close the descriptors and then do it explicit in code. Instead of such hacks we can use now daemonfd. This API can be also helpful to migrate system to platforms like CheriBSD. Reviewed by: brooks@, bcr@, jilles@ (earlier version) Differential Revision: https://reviews.freebsd.org/D13433
2017-12-23 18:07:43 +00:00
.Ft int
.Fn daemonfd "int chdirfd" "int nullfd"
BSD 4.4 Lite Lib Sources
1994-05-27 05:00:24 +00:00
.Sh DESCRIPTION
The
.Fn daemon
function is for programs wishing to detach themselves from the
controlling terminal and run in the background as system daemons.
.Pp
Unless the argument
.Fa nochdir
is non-zero,
.Fn daemon
Merge some updates and markup fixes from OpenBSD. This is mainly motivated by the new "CAVEATS" section. Inspired by: alfred noting NetBSD's merging OpenBSD's changes Obtained from: OpenBSD
2002-01-14 02:08:02 +00:00
changes the current working directory to the root
.Pq Pa / .
BSD 4.4 Lite Lib Sources
1994-05-27 05:00:24 +00:00
.Pp
Unless the argument
.Fa noclose
is non-zero,
.Fn daemon
Merge some updates and markup fixes from OpenBSD. This is mainly motivated by the new "CAVEATS" section. Inspired by: alfred noting NetBSD's merging OpenBSD's changes Obtained from: OpenBSD
2002-01-14 02:08:02 +00:00
will redirect standard input, standard output, and standard error to
.Pa /dev/null .
Introduce the daemonfd function. The daemonfd function is equivalent to the daemon(3) function expect that arguments are descriptors. For example dhclient(8) which is sandboxed is unable to open /dev/null to close stdio instead it's allows to fail daemon(3) function to close the descriptors and then do it explicit in code. Instead of such hacks we can use now daemonfd. This API can be also helpful to migrate system to platforms like CheriBSD. Reviewed by: brooks@, bcr@, jilles@ (earlier version) Differential Revision: https://reviews.freebsd.org/D13433
2017-12-23 18:07:43 +00:00
.Pp
The
.Fn daemonfd
function is equivalent to the
.Fn daemon
function except that arguments are the descriptors for the current working
directory and to the descriptor to
.Pa /dev/null .
.Pp
If
.Fa chdirfd
is equal to
.Pq -1
the current working directory is not changed.
.Pp
If
.Fa nullfd
is equals to
.Pq -1
the redirection of standard input, standard output, and standard error is not
closed.
Merge some updates and markup fixes from OpenBSD. This is mainly motivated by the new "CAVEATS" section. Inspired by: alfred noting NetBSD's merging OpenBSD's changes Obtained from: OpenBSD
2002-01-14 02:08:02 +00:00
.Sh RETURN VALUES
Introduce the daemonfd function. The daemonfd function is equivalent to the daemon(3) function expect that arguments are descriptors. For example dhclient(8) which is sandboxed is unable to open /dev/null to close stdio instead it's allows to fail daemon(3) function to close the descriptors and then do it explicit in code. Instead of such hacks we can use now daemonfd. This API can be also helpful to migrate system to platforms like CheriBSD. Reviewed by: brooks@, bcr@, jilles@ (earlier version) Differential Revision: https://reviews.freebsd.org/D13433
2017-12-23 18:07:43 +00:00
.Rv -std daemon daemonfd
BSD 4.4 Lite Lib Sources
1994-05-27 05:00:24 +00:00
.Sh ERRORS
mdoc(7) police: tidy up OpenBSD fixes.
2002-01-16 15:21:39 +00:00
The
BSD 4.4 Lite Lib Sources
1994-05-27 05:00:24 +00:00
.Fn daemon
Introduce the daemonfd function. The daemonfd function is equivalent to the daemon(3) function expect that arguments are descriptors. For example dhclient(8) which is sandboxed is unable to open /dev/null to close stdio instead it's allows to fail daemon(3) function to close the descriptors and then do it explicit in code. Instead of such hacks we can use now daemonfd. This API can be also helpful to migrate system to platforms like CheriBSD. Reviewed by: brooks@, bcr@, jilles@ (earlier version) Differential Revision: https://reviews.freebsd.org/D13433
2017-12-23 18:07:43 +00:00
and
.Fn daemonfd
mdoc(7) police: tidy up OpenBSD fixes.
2002-01-16 15:21:39 +00:00
function may fail and set
BSD 4.4 Lite Lib Sources
1994-05-27 05:00:24 +00:00
.Va errno
Merge some updates and markup fixes from OpenBSD. This is mainly motivated by the new "CAVEATS" section. Inspired by: alfred noting NetBSD's merging OpenBSD's changes Obtained from: OpenBSD
2002-01-14 02:08:02 +00:00
for any of the errors specified for the library functions
Remove ',' accidentally added after ".Xr fork 2".
2003-11-10 22:04:51 +00:00
.Xr fork 2
Introduce the daemonfd function. The daemonfd function is equivalent to the daemon(3) function expect that arguments are descriptors. For example dhclient(8) which is sandboxed is unable to open /dev/null to close stdio instead it's allows to fail daemon(3) function to close the descriptors and then do it explicit in code. Instead of such hacks we can use now daemonfd. This API can be also helpful to migrate system to platforms like CheriBSD. Reviewed by: brooks@, bcr@, jilles@ (earlier version) Differential Revision: https://reviews.freebsd.org/D13433
2017-12-23 18:07:43 +00:00
.Xr open 2,
Whitespace only change: trim trailing whitespace.
2000-10-30 13:23:19 +00:00
and
BSD 4.4 Lite Lib Sources
1994-05-27 05:00:24 +00:00
.Xr setsid 2 .
.Sh SEE ALSO
Specify that daemon(3) returns int, and standardise the phrasing in the ERRORS section a bit, as well as now specifying the return status.
1996-06-22 23:46:00 +00:00
.Xr fork 2 ,
Prevent abnormal termination of a child daemon process when created by a parent that is a session leader (e.g., login shell) by ignoring SIGHUP in before calling fork(2) and then restoring SIGHUP's action after setsid(3). Based on the patch by Martin Kammerhofer <mkamm@gmx.net>. PR: bin/25462 Reviewed by: bde, alex.neyman@auriga.ru
2003-11-10 22:01:42 +00:00
.Xr setsid 2 ,
.Xr sigaction 2
BSD 4.4 Lite Lib Sources
1994-05-27 05:00:24 +00:00
.Sh HISTORY
The
.Fn daemon
Correctly use .Fn instead of .Nm to reference function names in a bunch of man pages. Use the correct .Bx (BSD UNIX) or .At (AT&T UNIX) macros instead of explicitly specifying the version in the text in a bunch of man pages.
1996-08-22 23:31:07 +00:00
function first appeared in
.Bx 4.4 .
Introduce the daemonfd function. The daemonfd function is equivalent to the daemon(3) function expect that arguments are descriptors. For example dhclient(8) which is sandboxed is unable to open /dev/null to close stdio instead it's allows to fail daemon(3) function to close the descriptors and then do it explicit in code. Instead of such hacks we can use now daemonfd. This API can be also helpful to migrate system to platforms like CheriBSD. Reviewed by: brooks@, bcr@, jilles@ (earlier version) Differential Revision: https://reviews.freebsd.org/D13433
2017-12-23 18:07:43 +00:00
The
.Fn daemonfd
function first appeared in
.Fx 12.0 .
Merge some updates and markup fixes from OpenBSD. This is mainly motivated by the new "CAVEATS" section. Inspired by: alfred noting NetBSD's merging OpenBSD's changes Obtained from: OpenBSD
2002-01-14 02:08:02 +00:00
.Sh CAVEATS
Unless the
mdoc(7) police: tidy up OpenBSD fixes.
2002-01-16 15:21:39 +00:00
.Fa noclose
Merge some updates and markup fixes from OpenBSD. This is mainly motivated by the new "CAVEATS" section. Inspired by: alfred noting NetBSD's merging OpenBSD's changes Obtained from: OpenBSD
2002-01-14 02:08:02 +00:00
argument is non-zero,
.Fn daemon
will close the first three file descriptors and redirect them to
.Pa /dev/null .
Normally, these correspond to standard input, standard output, and
standard error.
mdoc(7) police: tidy up OpenBSD fixes.
2002-01-16 15:21:39 +00:00
However, if any of those file descriptors refer to something else, they
Merge some updates and markup fixes from OpenBSD. This is mainly motivated by the new "CAVEATS" section. Inspired by: alfred noting NetBSD's merging OpenBSD's changes Obtained from: OpenBSD
2002-01-14 02:08:02 +00:00
will still be closed, resulting in incorrect behavior of the calling program.
This can happen if any of standard input, standard output, or standard
error have been closed before the program was run.
Programs using
.Fn daemon
should therefore either call
.Fn daemon
before opening any files or sockets, or verify that any file
descriptors obtained have values greater than 2.
Prevent abnormal termination of a child daemon process when created by a parent that is a session leader (e.g., login shell) by ignoring SIGHUP in before calling fork(2) and then restoring SIGHUP's action after setsid(3). Based on the patch by Martin Kammerhofer <mkamm@gmx.net>. PR: bin/25462 Reviewed by: bde, alex.neyman@auriga.ru
2003-11-10 22:01:42 +00:00
.Pp
The
.Fn daemon
function temporarily ignores
.Dv SIGHUP
while calling
.Xr setsid 2
to prevent a parent session group leader's calls to
.Xr fork 2
and then
.Xr _exit 2
from prematurely terminating the child process.
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