xref: /dragonfly/share/man/man5/fstab.5 (revision 02fd838e) 
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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.\" $DragonFly: src/share/man/man5/fstab.5,v 1.5 2008/07/27 21:16:00 thomas Exp $
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32.Dd September 13, 2009
33.Dt FSTAB 5
34.Os
35.Sh NAME
36.Nm fstab
37.Nd static information about the file systems
38.Sh SYNOPSIS
39.In fstab.h
40.Sh DESCRIPTION
41The file
42.Nm
43contains descriptive information about the various file
44systems.
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 file system is described on a separate line;
50fields on each line are separated by tabs or spaces.
51The order of records in
52.Nm
53is important because
54.Xr fsck 8 ,
55.Xr mount 8 ,
56and
57.Xr umount 8
58sequentially iterate through
59.Nm
60doing their thing.
61.Pp
62The first field,
63.Pq Fa fs_spec ,
64describes the special file or
65remote file system to be mounted.
66This may be a
67.Pa /dev/<path> ,
68a label from a
69.Xr devtab 5
70(typically
71.Pa /etc/devtab ) ,
72or a
73.Pa <host>:<path>
74for NFS.
75Note that
76.Xr devtab 5
77labels maybe augmented with a
78.Pa .suffix
79trailer.
80For example
81.Pa mydisk.s1a .
82Also note
83.Pa /dev
84based paths can mount serial numbers similar to
85.Xr devtab 5
86labels by using the path
87.Pa /dev/serno/SERIALNO[.suffix] .
88.Pp
89The second field,
90.Pq Fa fs_file ,
91describes the mount point for the file system.
92For swap partitions, this field should be specified as
93.Dq none .
94.Pp
95The third field,
96.Pq Fa fs_vfstype ,
97describes the type of the file system.
98The system can support various file system types.
99Only the root,
100.Pa /usr ,
101and
102.Pa /tmp
103file systems need be statically
104compiled into the kernel;
105everything else will be automatically loaded at mount
106time.
107(Exception: the UFS family - FFS, MFS, and LFS cannot
108currently be demand-loaded.)  Some people still prefer to statically
109compile other file systems as well.
110.Pp
111The most common file system types are:
112.Bl -tag -width indent -offset indent
113.It Em HAMMER
114a local
115.Xr HAMMER 5
116file system
117.It Em ufs
118a local
119.Xr ffs 5
120.Ux
121file system
122.It Em mfs
123a local memory-based
124.Ux
125file system
126.It Em nfs
127a Sun Microsystems compatible
128.Dq "Network File System"
129.It Em swap
130a disk partition to be used for swapping
131.It Em msdos
132a local
133.Xr msdos 5
134DOS compatible file system
135.It Em cd9660
136a local CD-ROM file system (as per ISO 9660)
137.\" maybe also say Rock Ridge extensions are handled ?
138.It Em procfs
139a file system for accessing process data
140.El
141.Pp
142The fourth field,
143.Pq Fa fs_mntops ,
144describes the mount options associated with the file system.
145It is formatted as a comma separated list of options.
146It contains at least the type of mount (see
147.Fa fs_type
148below) plus any additional options
149appropriate to the file system type.
150See the options flag
151.Pq Fl o
152in the
153.Xr mount 8
154page and the file system specific page, such as
155.Xr mount_nfs 8 ,
156for additional options that may be specified.
157.Pp
158If the options ``userquota'' and/or ``groupquota'' are specified,
159the file system is automatically processed by the
160.Xr quotacheck 8
161command, and user and/or group disk quotas are enabled with
162.Xr quotaon 8 .
163By default,
164file system quotas are maintained in files named
165.Pa quota.user
166and
167.Pa quota.group
168which are located at the root of the associated file system.
169These defaults may be overridden by putting an equal sign
170and an alternative absolute pathname following the quota option.
171Thus, if the user quota file for
172.Pa /tmp
173is stored in
174.Pa /var/quotas/tmp.user ,
175this location can be specified as:
176.Bd -literal -offset indent
177userquota=/var/quotas/tmp.user
178.Ed
179.Pp
180If the option ``noauto'' is specified, the file system will not be automatically
181mounted at system startup.
182This is recommended for all remote file systems other than NFS,
183since only NFS mounts are delayed until after network initialization
184by the
185.Pp
186Swap partitions may specify the option ``crypt'' to automatically encrypt
187the swap partition with a random key.  Note that you will not be able to
188recover any kernel core dumps if you use this option.
189.Xr rc 8
190startup scripts.
191.Pp
192The type of the mount is extracted from the
193.Fa fs_mntops
194field and stored separately in the
195.Fa fs_type
196field (it is not deleted from the
197.Fa fs_mntops
198field).
199If
200.Fa fs_type
201is ``rw'' or ``ro'' then the file system whose name is given in the
202.Fa fs_file
203field is normally mounted read-write or read-only on the
204specified special file.
205If
206.Fa fs_type
207is ``sw'' then the special file is made available as a piece of swap
208space by the
209.Xr swapon 8
210command at the end of the system reboot procedure.
211The fields other than
212.Fa fs_spec
213and
214.Fa fs_type
215are unused.
216If
217.Fa fs_type
218is specified as ``xx'' the entry is ignored.
219This is useful to show disk partitions which are currently unused.
220.Pp
221The fifth field,
222.Pq Fa fs_freq ,
223is used for these file systems by the
224.Xr dump 8
225command to determine which file systems need to be dumped.
226If the fifth field is not present, a value of zero is returned and
227.Nm dump
228will assume that the file system does not need to be dumped.
229.Pp
230The sixth field,
231.Pq Fa fs_passno ,
232is used by the
233.Xr fsck 8
234program to determine the order in which file system checks are done
235at reboot time.
236The root file system should be specified with a
237.Fa fs_passno
238of 1, and other file systems should have a
239.Fa fs_passno
240of 2.
241File systems within a drive will be checked sequentially,
242but file systems on different drives will be checked at the
243same time to utilize parallelism available in the hardware.
244If the sixth field is not present or is zero,
245a value of zero is returned and
246.Xr fsck 8
247will assume that the file system does not need to be checked.
248.Bd -literal
249#define	FSTAB_RW	"rw"	/* read/write device */
250#define	FSTAB_RQ	"rq"	/* read/write with quotas */
251#define	FSTAB_RO	"ro"	/* read-only device */
252#define	FSTAB_SW	"sw"	/* swap device */
253#define	FSTAB_XX	"xx"	/* ignore totally */
254
255struct fstab {
256	char	*fs_spec;	/* block special device name */
257	char	*fs_file;	/* file system path prefix */
258	char	*fs_vfstype;	/* File system type, ufs, nfs */
259	char	*fs_mntops;	/* Mount options ala -o */
260	char	*fs_type;	/* FSTAB_* from fs_mntops */
261	int	fs_freq;	/* dump frequency, in days */
262	int	fs_passno;	/* pass number on parallel fsck */
263};
264.Ed
265.Pp
266The proper way to read records from
267.Nm
268is to use the routines
269.Xr getfsent 3 ,
270.Xr getfsspec 3 ,
271.Xr getfstype 3 ,
272and
273.Xr getfsfile 3 .
274.Sh FILES
275.Bl -tag -width /etc/fstab -compact
276.It Pa /etc/fstab
277The file
278.Nm
279resides in
280.Pa /etc .
281.El
282.Sh SEE ALSO
283.Xr getfsent 3 ,
284.Xr getvfsbyname 3 ,
285.Xr HAMMER 5 ,
286.Xr dump 8 ,
287.Xr fsck 8 ,
288.Xr mount 8 ,
289.Xr quotacheck 8 ,
290.Xr quotaon 8 ,
291.Xr swapon 8 ,
292.Xr umount 8
293.Sh HISTORY
294The
295.Nm
296file format appeared in
297.Bx 4.0 .
298