xref: /openbsd-src/share/man/man5/fstab.5 (revision d13be5d47e4149db2549a9828e244d59dbc43f15) 
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31.\"     @(#)fstab.5	8.1 (Berkeley) 6/5/93
32.\"
33.Dd $Mdocdate: April 17 2011 $
34.Dt FSTAB 5
35.Os
36.Sh NAME
37.Nm fstab
38.Nd static information about the filesystems
39.Sh SYNOPSIS
40.Fd #include <fstab.h>
41.Sh DESCRIPTION
42The
43.Nm
44file contains descriptive information about the various file systems.
45.Nm
46is only read by programs, and not written;
47it is the duty of the system administrator to properly create
48and maintain this file.
49Each filesystem is described on a separate line;
50fields on each line are separated by tabs or spaces.
51Lines beginning with the
52.Sq #
53character are comments and are ignored.
54The order of records in
55.Nm
56is important because
57.Xr fsck 8
58and
59.Xr mount 8
60sequentially iterate through
61.Nm
62doing their thing.
63.Pp
64A line has the following format:
65.Bd -literal -offset indent
66fs_spec fs_file fs_vfstype fs_mntops fs_freq fs_passno
67.Ed
68.Pp
69The first field,
70.Fa fs_spec ,
71describes the block special device or remote filesystem to be mounted.
72A block special device may be specified by pathname
73or by
74.Xr disklabel 8
75UID (DUID).
76For filesystems of type MFS
77the special file name is typically that of the primary swap area;
78if the keyword
79.Dq swap
80is used instead of a special file name,
81default configuration parameters are used.
82If a program needs the character special file name,
83the program must create it by appending an
84.Sq r
85after the last
86.Sq /
87in the special file name.
88.Pp
89The second field,
90.Fa fs_file ,
91describes the mount point for the filesystem.
92For swap partitions, this field should be specified as
93.Dq none .
94.Pp
95The third field,
96.Fa fs_vfstype ,
97describes the type of the filesystem.
98The system currently supports the following types of filesystems:
99.Pp
100.Bl -tag -width indent -offset indent -compact
101.It cd9660
102An ISO 9660 CD-ROM filesystem.
103.It ext2fs
104A local Linux compatible ext2fs
105filesystem.
106.It ffs
107A local
108.Ux
109filesystem.
110.It mfs
111A local memory-based
112.Ux
113filesystem.
114.It msdos
115An
116.Tn MS-DOS
117FAT filesystem.
118.It nfs
119A Sun Microsystems compatible Network File System.
120.It ntfs
121An NTFS filesystem.
122.It procfs
123A local filesystem containing process information.
124.It swap
125A disk partition to be used for swapping.
126.It udf
127A UDF filesystem.
128.It vnd
129A VND image file.
130.El
131.Pp
132The fourth field,
133.Fa fs_mntops ,
134describes the mount options associated with the filesystem.
135It is formatted as a comma separated list of options.
136It contains at least the type of mount (see
137.Fa fs_type
138below) plus any additional options appropriate to the filesystem type.
139.Pp
140The option
141.Dq auto
142can be used in the
143.Dq noauto
144form to cause
145a file system not to be mounted automatically (with
146.Ic mount -A
147or
148.Ic mount -a ,
149or at system boot time).
150.Pp
151If the options
152.Dq userquota
153and/or
154.Dq groupquota
155are specified, the filesystem is automatically processed by the
156.Xr quotacheck 8
157command, and user and/or group disk quotas are enabled with
158.Xr quotaon 8 .
159By default, filesystem quotas are maintained in files named
160.Pa quota.user
161and
162.Pa quota.group
163which are located at the root of the associated filesystem.
164These defaults may be overridden by putting an equal sign
165and an alternative absolute pathname following the quota option.
166Thus, if the user quota file for
167.Pa /tmp
168is stored in
169.Pa /var/quotas/tmp.user ,
170this location can be specified as:
171.Bd -literal -offset indent
172userquota=/var/quotas/tmp.user
173.Ed
174.Pp
175The type of the mount is extracted from the first parameter of the
176.Fa fs_mntops
177field and stored separately in the
178.Fa fs_type
179field (it is not deleted from the
180.Fa fs_mntops
181field).
182If
183.Fa fs_type
184is
185.Dq rw ,
186.Dq rq ,
187or
188.Dq ro
189then the filesystem whose name is given in the
190.Fa fs_file
191field is normally mounted read-write or read-only on the
192specified special file.
193If
194.Fa fs_type
195is
196.Dq sw
197then the special file is made available as a piece of swap space by the
198.Xr swapon 8
199command at the end of the system reboot procedure.
200The fields other than
201.Fa fs_spec
202and
203.Fa fs_type
204are unused.
205If
206.Fa fs_type
207is specified as
208.Dq xx
209the entry is ignored.
210This is useful to show disk partitions which are currently unused.
211.Pp
212The fifth field,
213.Fa fs_freq ,
214is used by the
215.Fl W
216and
217.Fl w
218options of
219.Xr dump 8
220to recommend which filesystems should be backed up.
221The value specifies the number of days
222after which a dump is regarded as being old;
223if it is not present, a value of zero is returned and
224.Xr dump 8
225will assume that the filesystem does not need to be dumped.
226.Pp
227The sixth field,
228.Fa fs_passno ,
229is used by the
230.Xr fsck 8
231program to determine the order in which filesystem checks are done
232at reboot time.
233The root filesystem should be specified with a
234.Fa fs_passno
235of 1, and other filesystems should have a
236.Fa fs_passno
237of 2.
238Filesystems within a drive will be checked sequentially,
239but filesystems on different drives will be checked at the
240same time to utilize parallelism available in the hardware.
241If the sixth field is not present or is zero,
242a value of zero is returned and
243.Xr fsck 8
244will assume that the filesystem does not need to be checked.
245.Bd -literal
246#define	FSTAB_RW	"rw"	/* read/write device */
247#define	FSTAB_RQ	"rq"	/* read/write with quotas *
248#define	FSTAB_RO	"ro"	/* read-only device */
249#define	FSTAB_SW	"sw"	/* swap device */
250#define	FSTAB_XX	"xx"	/* ignore totally */
251
252struct fstab {
253	char	*fs_spec;	/* block special device name */
254	char	*fs_file;	/* filesystem path prefix */
255	char	*fs_vfstype;	/* type of filesystem */
256	char	*fs_mntops;	/* comma separated mount options */
257	char	*fs_type;	/* rw, rq, ro, sw, or xx */
258	int	fs_freq;	/* dump frequency, in days */
259	int	fs_passno;	/* pass number on parallel fsck */
260};
261.Ed
262.Pp
263The proper way to read records from
264.Pa fstab
265is to use the routines
266.Xr getfsent 3 ,
267.Xr getfsspec 3 ,
268and
269.Xr getfsfile 3 .
270.Sh FILES
271.Bl -tag -width /etc/fstab -compact
272.It Pa /etc/fstab
273.El
274.Sh EXAMPLES
275Here is a sample
276.Pa /etc/fstab
277file:
278.Bd -literal -offset indent
279/dev/sd0b none swap sw
280/dev/sd1b none swap sw
281/dev/sd0a / ffs rw 1 1
282/dev/sd0e /var ffs rw,nodev,nosuid 1 2
283#/dev/sd0f /tmp ffs rw,nodev,nosuid 1 2
284swap /tmp mfs rw,nodev,nosuid,-s=153600 0 0
285/dev/sd0g /usr ffs rw,nodev 1 2
286/dev/sd0h /usr/local ffs rw,nodev 1 2
287/dev/sd0i /home ffs rw,nodev,nosuid 1 2
288/dev/sd0j /usr/src ffs rw,nodev,nosuid,softdep 1 2
289/dev/cd0a /cdrom cd9660 ro,noauto 0 0
2905b27c2761a9b0b06.i /mnt/key msdos rw,noauto 0 0
291server:/export/ports /usr/ports nfs rw,nodev,nosuid,soft,intr 0 0
292.Ed
293.Sh SEE ALSO
294.Xr quota 1 ,
295.Xr getfsent 3 ,
296.Xr fsck 8 ,
297.Xr mount 8 ,
298.Xr quotacheck 8 ,
299.Xr quotaon 8
300.Sh HISTORY
301The
302.Nm
303file format appeared in
304.Bx 4.0 .
305