1.\" Copyright (c) 1996 2.\" Mike Pritchard <[email protected]>. All rights reserved. 3.\" 4.\" Copyright (c) 1992, 1993, 1994 5.\" The Regents of the University of California. All rights reserved. 6.\" All rights reserved. 7.\" 8.\" This code is derived from software donated to Berkeley by 9.\" Jan-Simon Pendry. 10.\" 11.\" Redistribution and use in source and binary forms, with or without 12.\" modification, are permitted provided that the following conditions 13.\" are met: 14.\" 1. Redistributions of source code must retain the above copyright 15.\" notice, this list of conditions and the following disclaimer. 16.\" 2. Redistributions in binary form must reproduce the above copyright 17.\" notice, this list of conditions and the following disclaimer in the 18.\" documentation and/or other materials provided with the distribution. 19.\" 3. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" $FreeBSD$ 36.\" 37.Dd February 9, 2012 38.Dt DEVFS 5 39.Os 40.Sh NAME 41.Nm devfs 42.Nd device file system 43.Sh SYNOPSIS 44.Bd -literal 45devfs /dev devfs rw 0 0 46.Ed 47.Sh DESCRIPTION 48The device file system, or 49.Nm , 50provides access to kernel's device 51namespace in the global file system namespace. 52The conventional mount point is 53.Pa /dev . 54.Pp 55The file system includes several directories, links, symbolic links 56and devices, some of which can also be written. 57In a chroot'ed 58environment, 59.Nm 60can be used to create a new 61.Pa /dev 62mount point. 63.Pp 64The 65.Xr mknod 8 66tool can be used to recover deleted device entries under 67.Nm . 68.Pp 69The 70.Xr fdescfs 5 71filesystem is an alternate means for populating 72.Pa /dev/fd . 73The character devices that both 74.Nm 75and 76.Xr fdescfs 5 77present in 78.Pa /dev/fd 79correspond to the open file descriptors of the process 80accessing the directory. 81.Nm 82only creates files for the standard file descriptors 83.Pa 0 , 84.Pa 1 85and 86.Pa 2 . 87.Xr fdescfs 5 88creates files for all open descriptors. 89.Pp 90The options are as follows: 91.Bl -tag -width indent 92.It Fl o Ar options 93Use the specified mount 94.Ar options , 95as described in 96.Xr mount 8 . 97The following devfs file system-specific options are available: 98.Bl -tag -width indent 99.It Cm ruleset Ns No = Ns Ar ruleset 100Set ruleset number 101.Ar ruleset 102as the current ruleset for the mount-point and apply all its rules. 103If the ruleset number 104.Ar ruleset 105does not exist, an empty ruleset with the number 106.Ar ruleset 107is created. 108See 109.Xr devfs 8 110for more information on working with devfs rulesets. 111.El 112.El 113.Sh FILES 114.Bl -tag -width /dev/XXXX -compact 115.It Pa /dev 116The normal 117.Nm 118mount point. 119.El 120.Sh EXAMPLES 121To mount a 122.Nm 123volume located on 124.Pa /mychroot/dev : 125.Pp 126.Dl "mount -t devfs devfs /mychroot/dev" 127.Sh SEE ALSO 128.Xr fdescfs 5 , 129.Xr devfs 8 , 130.Xr mount 8 131.Sh HISTORY 132The 133.Nm 134file system first appeared in 135.Fx 2.0 . 136It became the preferred method for accessing devices in 137.Fx 5.0 138and the only method in 139.Fx 6.0 . 140The 141.Nm 142manual page first appeared in 143.Fx 2.2 . 144.Sh AUTHORS 145The 146.Nm 147manual page was written by 148.An Mike Pritchard Aq Mt [email protected] . 149