man/man5/fstab.5

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.\"     @(#)fstab.5	8.1 (Berkeley) 6/5/93
.\" $FreeBSD: src/share/man/man5/fstab.5,v 1.11.2.8 2003/02/10 12:21:08 des Exp $
.\" $DragonFly: src/share/man/man5/fstab.5,v 1.5 2008/07/27 21:16:00 thomas Exp $
.\"
.Dd September 13, 2009
.Dt FSTAB 5
.Os
.Sh NAME
.Nm fstab
.Nd static information about the file systems
.Sh SYNOPSIS
.In fstab.h
.Sh DESCRIPTION
The file
.Nm
contains descriptive information about the various file
systems.
.Nm
is only read by programs, and not written;
it is the duty of the system administrator to properly create
and maintain this file.
Each file system is described on a separate line;
fields on each line are separated by tabs or spaces.
The order of records in
.Nm
is important because
.Xr fsck 8 ,
.Xr mount 8 ,
and
.Xr umount 8
sequentially iterate through
.Nm
doing their thing.
.Pp
The first field,
.Pq Fa fs_spec ,
describes the special file or
remote file system to be mounted.
This may be a
.Pa /dev/<path> ,
a label from a
.Xr devtab 5
(typically
.Pa /etc/devtab ) ,
or a
.Pa <host>:<path>
for NFS.
Note that
.Xr devtab 5
labels maybe augmented with a
.Pa .suffix
trailer.
For example
.Pa mydisk.s1a .
Also note
.Pa /dev
based paths can mount serial numbers similar to
.Xr devtab 5
labels by using the path
.Pa /dev/serno/SERIALNO[.suffix] .
.Pp
The second field,
.Pq Fa fs_file ,
describes the mount point for the file system.
For swap partitions, this field should be specified as
.Dq none .
.Pp
The third field,
.Pq Fa fs_vfstype ,
describes the type of the file system.
The system can support various file system types.
Only the root,
.Pa /usr ,
and
.Pa /tmp
file systems need be statically
compiled into the kernel;
everything else will be automatically loaded at mount
time.
(Exception: the UFS family - FFS, MFS, and LFS cannot
currently be demand-loaded.)  Some people still prefer to statically
compile other file systems as well.
.Pp
The most common file system types are:
.Bl -tag -width indent -offset indent
.It Em HAMMER
a local
.Xr HAMMER 5
file system
.It Em ufs
a local
.Xr ffs 5
.Ux
file system
.It Em mfs
a local memory-based
.Ux
file system
.It Em nfs
a Sun Microsystems compatible
.Dq "Network File System"
.It Em swap
a disk partition to be used for swapping
.It Em msdos
a local
.Xr msdos 5
DOS compatible file system
.It Em cd9660
a local CD-ROM file system (as per ISO 9660)
.\" maybe also say Rock Ridge extensions are handled ?
.It Em procfs
a file system for accessing process data
.El
.Pp
The fourth field,
.Pq Fa fs_mntops ,
describes the mount options associated with the file system.
It is formatted as a comma separated list of options.
It contains at least the type of mount (see
.Fa fs_type
below) plus any additional options
appropriate to the file system type.
See the options flag
.Pq Fl o
in the
.Xr mount 8
page and the file system specific page, such as
.Xr mount_nfs 8 ,
for additional options that may be specified.
.Pp
If the options ``userquota'' and/or ``groupquota'' are specified,
the file system is automatically processed by the
.Xr quotacheck 8
command, and user and/or group disk quotas are enabled with
.Xr quotaon 8 .
By default,
file system quotas are maintained in files named
.Pa quota.user
and
.Pa quota.group
which are located at the root of the associated file system.
These defaults may be overridden by putting an equal sign
and an alternative absolute pathname following the quota option.
Thus, if the user quota file for
.Pa /tmp
is stored in
.Pa /var/quotas/tmp.user ,
this location can be specified as:
.Bd -literal -offset indent
userquota=/var/quotas/tmp.user
.Ed
.Pp
If the option ``noauto'' is specified, the file system will not be automatically
mounted at system startup.
This is recommended for all remote file systems other than NFS,
since only NFS mounts are delayed until after network initialization
by the
.Xr rc 8
startup scripts.
.Pp
The type of the mount is extracted from the
.Fa fs_mntops
field and stored separately in the
.Fa fs_type
field (it is not deleted from the
.Fa fs_mntops
field).
If
.Fa fs_type
is ``rw'' or ``ro'' then the file system whose name is given in the
.Fa fs_file
field is normally mounted read-write or read-only on the
specified special file.
If
.Fa fs_type
is ``sw'' then the special file is made available as a piece of swap
space by the
.Xr swapon 8
command at the end of the system reboot procedure.
The fields other than
.Fa fs_spec
and
.Fa fs_type
are unused.
If
.Fa fs_type
is specified as ``xx'' the entry is ignored.
This is useful to show disk partitions which are currently unused.
.Pp
The fifth field,
.Pq Fa fs_freq ,
is used for these file systems by the
.Xr dump 8
command to determine which file systems need to be dumped.
If the fifth field is not present, a value of zero is returned and
.Nm dump
will assume that the file system does not need to be dumped.
.Pp
The sixth field,
.Pq Fa fs_passno ,
is used by the
.Xr fsck 8
program to determine the order in which file system checks are done
at reboot time.
The root file system should be specified with a
.Fa fs_passno
of 1, and other file systems should have a
.Fa fs_passno
of 2.
File systems within a drive will be checked sequentially,
but file systems on different drives will be checked at the
same time to utilize parallelism available in the hardware.
If the sixth field is not present or is zero,
a value of zero is returned and
.Xr fsck 8
will assume that the file system does not need to be checked.
.Bd -literal
#define	FSTAB_RW	"rw"	/* read/write device */
#define	FSTAB_RQ	"rq"	/* read/write with quotas */
#define	FSTAB_RO	"ro"	/* read-only device */
#define	FSTAB_SW	"sw"	/* swap device */
#define	FSTAB_XX	"xx"	/* ignore totally */

struct fstab {
	char	*fs_spec;	/* block special device name */
	char	*fs_file;	/* file system path prefix */
	char	*fs_vfstype;	/* File system type, ufs, nfs */
	char	*fs_mntops;	/* Mount options ala -o */
	char	*fs_type;	/* FSTAB_* from fs_mntops */
	int	fs_freq;	/* dump frequency, in days */
	int	fs_passno;	/* pass number on parallel fsck */
};
.Ed
.Pp
The proper way to read records from
.Nm
is to use the routines
.Xr getfsent 3 ,
.Xr getfsspec 3 ,
.Xr getfstype 3 ,
and
.Xr getfsfile 3 .
.Sh FILES
.Bl -tag -width /etc/fstab -compact
.It Pa /etc/fstab
The file
.Nm
resides in
.Pa /etc .
.El
.Sh SEE ALSO
.Xr getfsent 3 ,
.Xr getvfsbyname 3 ,
.Xr HAMMER 5 ,
.Xr dump 8 ,
.Xr fsck 8 ,
.Xr mount 8 ,
.Xr quotacheck 8 ,
.Xr quotaon 8 ,
.Xr swapon 8 ,
.Xr umount 8
.Sh HISTORY
The
.Nm
file format appeared in
.Bx 4.0 .