freebsd-nq/share/man/man5/devfs.5

.\" Copyright (c) 1996
.\"	Mike Pritchard <mpp@FreeBSD.org>.  All rights reserved.
.\"
.\" Copyright (c) 1992, 1993, 1994
.\"	The Regents of the University of California.  All rights reserved.
.\" All rights reserved.
.\"
.\" This code is derived from software donated to Berkeley by
.\" Jan-Simon Pendry.
.\"
.\" 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. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    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.
.\"
.\" $FreeBSD$
.\"
.Dd September 18, 2010
.Dt DEVFS 5
.Os
.Sh NAME
.Nm devfs
.Nd device file system
.Sh SYNOPSIS
.Bd -literal
devfs	/dev	devfs rw 0 0
.Ed
.Sh DESCRIPTION
The device file system, or
.Nm ,
provides access to kernel's device
namespace in the global file system namespace.
The conventional mount point is
.Pa /dev .
.Pp
The file system includes several directories, links, symbolic links
and devices, some of which can also be written.
In a chroot'ed
environment,
.Nm
can be used to create a new
.Pa /dev
mount point.
.Pp
The
.Xr mknod 8
tool can be used to recover deleted device entries under
.Nm .
.Pp
The
.Xr fdescfs 5
filesystem is an alternate means for populating
.Pa /dev/fd .
The character devices that both
.Nm
and
.Xr fdescfs 5
present in
.Pa /dev/fd
correspond to the open file descriptors of the process
accessing the directory.
.Nm
only creates files for the standard file descriptors
.Pa 0 ,
.Pa 1
and
.Pa 2 .
.Xr fdescfs 5
creates files for all open descriptors.
.Sh FILES
.Bl -tag -width /dev/XXXX -compact
.It Pa /dev
The normal
.Nm
mount point.
.El
.Sh EXAMPLES
To mount a
.Nm
volume located on
.Pa /mychroot/dev :
.Pp
.Dl "mount -t devfs devfs /mychroot/dev"
.Sh SEE ALSO
.Xr devfs 8 ,
.Xr fdescfs 5 ,
.Xr mount 8
.Sh HISTORY
The
.Nm
file system first appeared in
.Fx 2.0 .
It became the preferred method for accessing devices in
.Fx 5.0
and the only method in
.Fx 6.0 .
The
.Nm
manual page first appeared in
.Fx 2.2 .
.Sh AUTHORS
The
.Nm
manual page was written by
.An Mike Pritchard Aq mpp@FreeBSD.org .
Actually add the man page. 1996-12-14 22:34:11 +00:00			`.\" Copyright (c) 1996`
			`.\" Mike Pritchard <mpp@FreeBSD.org>. All rights reserved.`
			`.\"`
			`.\" Copyright (c) 1992, 1993, 1994`
			`.\" The Regents of the University of California. All rights reserved.`
			`.\" All rights reserved.`
			`.\"`
			`.\" This code is derived from software donated to Berkeley by`
			`.\" Jan-Simon Pendry.`
			`.\"`
			`.\" 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. All advertising materials mentioning features or use of this software`
			`.\" must display the following acknowledgement:`
			`.\" This product includes software developed by the University of`
			`.\" California, Berkeley and its contributors.`
			`.\" 4. Neither the name of the University nor the names of its contributors`
			`.\" 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.`
add missing cvs Id lines. 1997-03-07 03:28:23 +00:00			`.\"`
$Id$ -> $FreeBSD$ 1999-08-28 00:22:10 +00:00			`.\" $FreeBSD$`
add missing cvs Id lines. 1997-03-07 03:28:23 +00:00			`.\"`
Note that devfs(5) and fdescfs(5) both create /dev/fd file descriptors. PR: 144534 Submitted by: Matthew Seaman <m.seaman at infracaninophile co uk> Patch by: Matthew Seaman, keramida Approved by: keramida (mentor) MFC after: 1 week 2010-09-18 19:23:14 +00:00			`.Dd September 18, 2010`
Various man page cleanup: - Sort xrefs - FreeBSD.ORG -> FreeBSD.org - Be consistent with section names as outlined in mdoc(7). - Other misc mdoc cleanup. PR: doc/13144 Submitted by: Alexey M. Zelkin <phantom@cris.net> 1999-08-15 10:48:36 +00:00			`.Dt DEVFS 5`
mdoc(7) police: removed HISTORY info from the .Os call. 2001-07-10 15:31:11 +00:00			`.Os`
Actually add the man page. 1996-12-14 22:34:11 +00:00			`.Sh NAME`
			`.Nm devfs`
Uniformly refer to a file system as "file system". Approved by: re 2002-12-12 17:26:04 +00:00			`.Nd device file system`
Actually add the man page. 1996-12-14 22:34:11 +00:00			`.Sh SYNOPSIS`
Deal with unsafe tab characters. 2004-07-02 19:55:26 +00:00			`.Bd -literal`
/devs -> /dev PR: 25252 Submitted by: Christian Weisgerber <naddy@mips.inka.de> Approved by: nik, phk (via nik) 2001-03-15 02:06:44 +00:00			`devfs /dev devfs rw 0 0`
Deal with unsafe tab characters. 2004-07-02 19:55:26 +00:00			`.Ed`
Actually add the man page. 1996-12-14 22:34:11 +00:00			`.Sh DESCRIPTION`
Uniformly refer to a file system as "file system". Approved by: re 2002-12-12 17:26:04 +00:00			`The device file system, or`
mdoc(7) police: use the new features of the Nm macro. 2000-11-20 18:41:33 +00:00			`.Nm ,`
Removed whitespace at end-of-line; no content changes. I simply did cd src/share; find man[1-9] -type f\|xargs perl -pi -e 's/[ \t]+$//' BTW, what editors are the culprits? I'm using vim and it shows me whitespace at EOL in troff files with a thick blue block... Reviewed by: Silence from cvs diff -b MFC after: 7 days 2001-07-14 19:41:16 +00:00			`provides access to kernel's device`
Uniformly refer to a file system as "file system". Approved by: re 2002-12-12 17:26:04 +00:00			`namespace in the global file system namespace.`
Actually add the man page. 1996-12-14 22:34:11 +00:00			`The conventional mount point is`
/devs -> /dev PR: 25252 Submitted by: Christian Weisgerber <naddy@mips.inka.de> Approved by: nik, phk (via nik) 2001-03-15 02:06:44 +00:00			`.Pa /dev .`
Actually add the man page. 1996-12-14 22:34:11 +00:00			`.Pp`
Uniformly refer to a file system as "file system". Approved by: re 2002-12-12 17:26:04 +00:00			`The file system includes several directories, links, symbolic links`
Mechanically kill hard sentence breaks and double whitespaces. 2004-07-03 18:29:24 +00:00			`and devices, some of which can also be written.`
			`In a chroot'ed`
Actually add the man page. 1996-12-14 22:34:11 +00:00			`environment,`
			`.Nm`
			`can be used to create a new`
/devs -> /dev PR: 25252 Submitted by: Christian Weisgerber <naddy@mips.inka.de> Approved by: nik, phk (via nik) 2001-03-15 02:06:44 +00:00			`.Pa /dev`
Actually add the man page. 1996-12-14 22:34:11 +00:00			`mount point.`
Explicitly state that mknod(8) can be used to undelete entries under devfs. 2003-12-29 00:40:44 +00:00			`.Pp`
			`The`
			`.Xr mknod 8`
Assorted markup, spelling, and grammar fixes. 2004-06-16 08:33:57 +00:00			`tool can be used to recover deleted device entries under`
			`.Nm .`
Note that devfs(5) and fdescfs(5) both create /dev/fd file descriptors. PR: 144534 Submitted by: Matthew Seaman <m.seaman at infracaninophile co uk> Patch by: Matthew Seaman, keramida Approved by: keramida (mentor) MFC after: 1 week 2010-09-18 19:23:14 +00:00			`.Pp`
			`The`
			`.Xr fdescfs 5`
			`filesystem is an alternate means for populating`
			`.Pa /dev/fd .`
			`The character devices that both`
			`.Nm`
			`and`
			`.Xr fdescfs 5`
			`present in`
			`.Pa /dev/fd`
			`correspond to the open file descriptors of the process`
			`accessing the directory.`
			`.Nm`
			`only creates files for the standard file descriptors`
			`.Pa 0 ,`
			`.Pa 1`
			`and`
			`.Pa 2 .`
			`.Xr fdescfs 5`
			`creates files for all open descriptors.`
Actually add the man page. 1996-12-14 22:34:11 +00:00			`.Sh FILES`
/devs -> /dev PR: 25252 Submitted by: Christian Weisgerber <naddy@mips.inka.de> Approved by: nik, phk (via nik) 2001-03-15 02:06:44 +00:00			`.Bl -tag -width /dev/XXXX -compact`
			`.It Pa /dev`
Actually add the man page. 1996-12-14 22:34:11 +00:00			`The normal`
Removed whitespace at end-of-line; no content changes. I simply did cd src/share; find man[1-9] -type f\|xargs perl -pi -e 's/[ \t]+$//' BTW, what editors are the culprits? I'm using vim and it shows me whitespace at EOL in troff files with a thick blue block... Reviewed by: Silence from cvs diff -b MFC after: 7 days 2001-07-14 19:41:16 +00:00			`.Nm`
Actually add the man page. 1996-12-14 22:34:11 +00:00			`mount point.`
			`.El`
Markup fixes. 2006-09-18 15:24:20 +00:00			`.Sh EXAMPLES`
			`To mount a`
			`.Nm`
			`volume located on`
Clarify devfs manpages slightly. mount(8): add xref to devfs(5) devfs(5): change example to something more likely to be useful (it is not necessary to mount a devfs on /dev manually, but for chroots/jails it is often needed), mention since when devfs is preferred to device nodes on ufs PR: 146600 MFC after: 2 weeks 2010-05-29 20:24:01 +00:00			`.Pa /mychroot/dev :`
Markup fixes. 2006-09-18 15:24:20 +00:00			`.Pp`
Clarify devfs manpages slightly. mount(8): add xref to devfs(5) devfs(5): change example to something more likely to be useful (it is not necessary to mount a devfs on /dev manually, but for chroots/jails it is often needed), mention since when devfs is preferred to device nodes on ufs PR: 146600 MFC after: 2 weeks 2010-05-29 20:24:01 +00:00			`.Dl "mount -t devfs devfs /mychroot/dev"`
Actually add the man page. 1996-12-14 22:34:11 +00:00			`.Sh SEE ALSO`
Remove reference to mount_devfs(8), since mount(8) no longer invokes this mount_devfs when mounting devfs file systems. 2006-05-18 13:37:13 +00:00			`.Xr devfs 8 ,`
Note that devfs(5) and fdescfs(5) both create /dev/fd file descriptors. PR: 144534 Submitted by: Matthew Seaman <m.seaman at infracaninophile co uk> Patch by: Matthew Seaman, keramida Approved by: keramida (mentor) MFC after: 1 week 2010-09-18 19:23:14 +00:00			`.Xr fdescfs 5 ,`
Remove reference to mount_devfs(8), since mount(8) no longer invokes this mount_devfs when mounting devfs file systems. 2006-05-18 13:37:13 +00:00			`.Xr mount 8`
Actually add the man page. 1996-12-14 22:34:11 +00:00			`.Sh HISTORY`
			`The`
Removed whitespace at end-of-line; no content changes. I simply did cd src/share; find man[1-9] -type f\|xargs perl -pi -e 's/[ \t]+$//' BTW, what editors are the culprits? I'm using vim and it shows me whitespace at EOL in troff files with a thick blue block... Reviewed by: Silence from cvs diff -b MFC after: 7 days 2001-07-14 19:41:16 +00:00			`.Nm`
Uniformly refer to a file system as "file system". Approved by: re 2002-12-12 17:26:04 +00:00			`file system first appeared in`
devfs(5): Also mention when device nodes on ufs stopped working (6.0), as requested by some people. MFC after: 2 weeks 2010-05-30 13:32:39 +00:00			`.Fx 2.0 .`
			`It became the preferred method for accessing devices in`
			`.Fx 5.0`
			`and the only method in`
			`.Fx 6.0 .`
Get the HISTORY section right. 1996-12-14 22:38:09 +00:00			`The`
Actually add the man page. 1996-12-14 22:34:11 +00:00			`.Nm`
Removed whitespace at end-of-line; no content changes. I simply did cd src/share; find man[1-9] -type f\|xargs perl -pi -e 's/[ \t]+$//' BTW, what editors are the culprits? I'm using vim and it shows me whitespace at EOL in troff files with a thick blue block... Reviewed by: Silence from cvs diff -b MFC after: 7 days 2001-07-14 19:41:16 +00:00			`manual page first appeared in`
Actually add the man page. 1996-12-14 22:34:11 +00:00			`.Fx 2.2 .`
.Sh AUTHOR -> .Sh AUTHORS according to mdoc specs. Use .An/.Aq. 1998-03-12 07:31:21 +00:00			`.Sh AUTHORS`
Removed whitespace at end-of-line; no content changes. I simply did cd src/share; find man[1-9] -type f\|xargs perl -pi -e 's/[ \t]+$//' BTW, what editors are the culprits? I'm using vim and it shows me whitespace at EOL in troff files with a thick blue block... Reviewed by: Silence from cvs diff -b MFC after: 7 days 2001-07-14 19:41:16 +00:00			`The`
Actually add the man page. 1996-12-14 22:34:11 +00:00			`.Nm`
.Sh AUTHOR -> .Sh AUTHORS according to mdoc specs. Use .An/.Aq. 1998-03-12 07:31:21 +00:00			`manual page was written by`
Remove reference to mount_devfs(8), since mount(8) no longer invokes this mount_devfs when mounting devfs file systems. 2006-05-18 13:37:13 +00:00			`.An Mike Pritchard Aq mpp@FreeBSD.org .`