xref: /dragonfly/share/man/man5/fstab.5 (revision 16dd80e4) 
1.\" Copyright (c) 1980, 1989, 1991, 1993
2.\"	The Regents of the University of California.  All rights reserved.
3.\"
4.\" Redistribution and use in source and binary forms, with or without
5.\" modification, are permitted provided that the following conditions
6.\" are met:
7.\" 1. Redistributions of source code must retain the above copyright
8.\"    notice, this list of conditions and the following disclaimer.
9.\" 2. Redistributions in binary form must reproduce the above copyright
10.\"    notice, this list of conditions and the following disclaimer in the
11.\"    documentation and/or other materials provided with the distribution.
12.\" 3. Neither the name of the University nor the names of its contributors
13.\"    may be used to endorse or promote products derived from this software
14.\"    without specific prior written permission.
15.\"
16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26.\" SUCH DAMAGE.
27.\"
28.\"     @(#)fstab.5	8.1 (Berkeley) 6/5/93
29.\" $FreeBSD: src/share/man/man5/fstab.5,v 1.11.2.8 2003/02/10 12:21:08 des Exp $
30.\"
31.Dd September 13, 2009
32.Dt FSTAB 5
33.Os
34.Sh NAME
35.Nm fstab
36.Nd static information about the file systems
37.Sh SYNOPSIS
38.In fstab.h
39.Sh DESCRIPTION
40The file
41.Nm
42contains descriptive information about the various file
43systems.
44.Nm
45is only read by programs, and not written;
46it is the duty of the system administrator to properly create
47and maintain this file.
48Each file system is described on a separate line;
49fields on each line are separated by tabs or spaces.
50The order of records in
51.Nm
52is important because
53.Xr fsck 8 ,
54.Xr mount 8 ,
55and
56.Xr umount 8
57sequentially iterate through
58.Nm
59doing their thing.
60.Pp
61The first field,
62.Pq Fa fs_spec ,
63describes the special file or
64remote file system to be mounted.
65This may be a
66.Pa /dev/<path> ,
67a label from a
68.Xr devtab 5
69(typically
70.Pa /etc/devtab ) ,
71or a
72.Pa <host>:<path>
73for NFS.
74Note that
75.Xr devtab 5
76labels maybe augmented with a
77.Pa .suffix
78trailer.
79For example
80.Pa mydisk.s1a .
81Also note
82.Pa /dev
83based paths can mount serial numbers similar to
84.Xr devtab 5
85labels by using the path
86.Pa /dev/serno/SERIALNO[.suffix] .
87.Pp
88The second field,
89.Pq Fa fs_file ,
90describes the mount point for the file system.
91For swap partitions, this field should be specified as
92.Dq none .
93.Pp
94The third field,
95.Pq Fa fs_vfstype ,
96describes the type of the file system.
97The system can support various file system types.
98Only the root,
99.Pa /usr ,
100and
101.Pa /tmp
102file systems need be statically
103compiled into the kernel;
104everything else will be automatically loaded at mount
105time.
106(Exception: the UFS family - FFS, MFS, and LFS cannot
107currently be demand-loaded.)  Some people still prefer to statically
108compile other file systems as well.
109.Pp
110The most common file system types are:
111.Bl -tag -width indent -offset indent
112.It Em HAMMER
113a local
114.Xr HAMMER 5
115file system
116.It Em ufs
117a local
118.Xr ffs 5
119.Ux
120file system
121.It Em mfs
122a local memory-based
123.Ux
124file system
125.It Em nfs
126a Sun Microsystems compatible
127.Dq "Network File System"
128.It Em swap
129a disk partition to be used for swapping
130.It Em msdos
131a local
132.Xr msdos 5
133DOS compatible file system
134.It Em cd9660
135a local CD-ROM file system (as per ISO 9660)
136.\" maybe also say Rock Ridge extensions are handled ?
137.It Em procfs
138a file system for accessing process data
139.El
140.Pp
141The fourth field,
142.Pq Fa fs_mntops ,
143describes the mount options associated with the file system.
144It is formatted as a comma separated list of options.
145It contains at least the type of mount (see
146.Fa fs_type
147below) plus any additional options
148appropriate to the file system type.
149See the options flag
150.Pq Fl o
151in the
152.Xr mount 8
153page and the file system specific page, such as
154.Xr mount_nfs 8 ,
155for additional options that may be specified.
156.Pp
157If the options ``userquota'' and/or ``groupquota'' are specified,
158the file system is automatically processed by the
159.Xr quotacheck 8
160command, and user and/or group disk quotas are enabled with
161.Xr quotaon 8 .
162By default,
163file system quotas are maintained in files named
164.Pa quota.user
165and
166.Pa quota.group
167which are located at the root of the associated file system.
168These defaults may be overridden by putting an equal sign
169and an alternative absolute pathname following the quota option.
170Thus, if the user quota file for
171.Pa /tmp
172is stored in
173.Pa /var/quotas/tmp.user ,
174this location can be specified as:
175.Bd -literal -offset indent
176userquota=/var/quotas/tmp.user
177.Ed
178.Pp
179If the option ``noauto'' is specified, the file system will not be automatically
180mounted at system startup.
181This is recommended for all remote file systems other than NFS,
182since only NFS mounts are delayed until after network initialization
183by the
184.Xr rc 8
185startup scripts.
186.Pp
187Swap partitions may specify the option ``crypt'' to automatically encrypt
188the swap partition with a random key.  Note that you will not be able to
189recover any kernel core dumps if you use this option.
190.Pp
191The type of the mount is extracted from the
192.Fa fs_mntops
193field and stored separately in the
194.Fa fs_type
195field (it is not deleted from the
196.Fa fs_mntops
197field).
198If
199.Fa fs_type
200is ``rw'' or ``ro'' then the file system whose name is given in the
201.Fa fs_file
202field is normally mounted read-write or read-only on the
203specified special file.
204If
205.Fa fs_type
206is ``sw'' then the special file is made available as a piece of swap
207space by the
208.Xr swapon 8
209command at the end of the system reboot procedure.
210The fields other than
211.Fa fs_spec
212and
213.Fa fs_type
214are unused.
215If
216.Fa fs_type
217is specified as ``xx'' the entry is ignored.
218This is useful to show disk partitions which are currently unused.
219.Pp
220The fifth field,
221.Pq Fa fs_freq ,
222is used for these file systems by the
223.Xr dump 8
224command to determine which file systems need to be dumped.
225If the fifth field is not present, a value of zero is returned and
226.Nm dump
227will assume that the file system does not need to be dumped.
228.Pp
229The sixth field,
230.Pq Fa fs_passno ,
231is used by the
232.Xr fsck 8
233program to determine the order in which file system checks are done
234at reboot time.
235The root file system should be specified with a
236.Fa fs_passno
237of 1, and other file systems should have a
238.Fa fs_passno
239of 2.
240File systems within a drive will be checked sequentially,
241but file systems on different drives will be checked at the
242same time to utilize parallelism available in the hardware.
243If the sixth field is not present or is zero,
244a value of zero is returned and
245.Xr fsck 8
246will assume that the file system does not need to be checked.
247.Bd -literal
248#define	FSTAB_RW	"rw"	/* read/write device */
249#define	FSTAB_RQ	"rq"	/* read/write with quotas */
250#define	FSTAB_RO	"ro"	/* read-only device */
251#define	FSTAB_SW	"sw"	/* swap device */
252#define	FSTAB_XX	"xx"	/* ignore totally */
253
254struct fstab {
255	char	*fs_spec;	/* block special device name */
256	char	*fs_file;	/* file system path prefix */
257	char	*fs_vfstype;	/* File system type, ufs, nfs */
258	char	*fs_mntops;	/* Mount options ala -o */
259	char	*fs_type;	/* FSTAB_* from fs_mntops */
260	int	fs_freq;	/* dump frequency, in days */
261	int	fs_passno;	/* pass number on parallel fsck */
262};
263.Ed
264.Pp
265The proper way to read records from
266.Nm
267is to use the routines
268.Xr getfsent 3 ,
269.Xr getfsspec 3 ,
270.Xr getfstype 3 ,
271and
272.Xr getfsfile 3 .
273.Sh FILES
274.Bl -tag -width /etc/fstab -compact
275.It Pa /etc/fstab
276The file
277.Nm
278resides in
279.Pa /etc .
280.El
281.Sh SEE ALSO
282.Xr getfsent 3 ,
283.Xr getvfsbyname 3 ,
284.Xr HAMMER 5 ,
285.Xr dump 8 ,
286.Xr fsck 8 ,
287.Xr mount 8 ,
288.Xr quotacheck 8 ,
289.Xr quotaon 8 ,
290.Xr swapon 8 ,
291.Xr umount 8
292.Sh HISTORY
293The
294.Nm
295file format appeared in
296.Bx 4.0 .
297