Each configuration line/record in
fstab
has the format:
fs_spec
fs_file
fs_vfstype
fs_mntops
fs_freq
fs_passno
The first field,
(fs_spec
),
describes the block special device or
remote filesystem to be mounted.
For filesystems of type
ffs,
the special file name is the block special file name,
and not the character special file name.
If a program needs the character special file name,
the program must create it by appending a
``r''
after the
last
``/''
in the special file name.
The second field,
(fs_file
),
describes the mount point for the filesystem.
For swap and dump partitions, this field should be specified as
``none''.
The third field,
(fs_vfstype
),
describes the type of the filesystem.
The system currently supports these filesystems:
/dev/fd
.
The fourth field,
(fs_mntops
),
describes the mount options associated with the filesystem.
It is formatted as a comma separated list of options.
It contains at least the type of mount (see
fs_type
below) plus any additional options
appropriate to the filesystem type.
The option ``auto'' can be used in the ``noauto'' form to cause a file system not to be mounted automatically (with ``mount -a'' , or system boot time).
If the options
``userquota''
and/or
``groupquota''
are specified,
the filesystem is automatically processed by the
quotacheck(8)
command, and user and/or group disk quotas are enabled with
quotaon(8).
By default,
filesystem quotas are maintained in files named
quota.user
and
quota.group
which are located at the root of the associated filesystem.
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
/tmp
is stored in
/var/quotas/tmp.user
,
this location can be specified as:
userquota=/var/quotas/tmp.user
The type of the mount is extracted from the
fs_mntops
field and stored separately in the
fs_type
field (it is not deleted from the
fs_mntops
field).
If
fs_type
is
``rw''
or
``ro''
then the filesystem whose name is given in the
fs_file
field is normally mounted read-write or read-only on the
specified special file.
If
fs_type
is
``sw''
or
``dp''
then the special file is made available as a piece of swap
or dump
space by the
swapctl(8)
command towards the beginning of the system reboot procedure.
See
swapctl(8)
for more information on configuring swap and dump devices.
The fields other than
fs_spec
and
fs_type
are unused.
If
fs_type
is specified as
``xx''
the entry is ignored.
This is useful to show disk partitions which are currently unused.
The fifth field,
(fs_freq
),
is used for these filesystems by the
dump(8)
command to determine which filesystems need to be dumped.
If the fifth field is not present, a value of zero is returned and
dump(8)
will assume that the filesystem does not need to be dumped.
The sixth field,
(
struct fstab {
char *fs_spec; /* block special device name */
char *fs_file; /* filesystem path prefix */
char *fs_vfstype; /* type of filesystem */
char *fs_mntops; /* comma separated mount options */
char *fs_type; /* rw, ro, sw, or xx */
int fs_freq; /* dump frequency, in days */
int fs_passno; /* pass number on parallel fsck */
};
fs_passno
),
is used by the
fsck(8)
program to determine the order in which filesystem checks are done
at reboot time.
The root filesystem should be specified with a
fs_passno
of 1, and other filesystems should have a
fs_passno
of 2.
Filesystems within a drive will be checked sequentially,
but filesystems on different drives will be checked at the
same time to use parallelism available in the hardware.
If the sixth field is not present or zero,
a value of zero is returned and
fsck(8)
will assume that the filesystem does not need to be checked.
#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_DP "dp" /* dump device */
#define FSTAB_XX "xx" /* ignore totally */
The proper way to read records from
fstab
is to use the routines
getfsent(3),
getfsspec(3),
and
getfsfile(3).
/etc/fstab
/usr/share/examples/fstab/