FSTAB(5) BSD Programmer's Manual FSTAB(5)
f
\bfs
\bst
\bta
\bab
\bb - static information about the filesystems
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#
\b#i
\bin
\bnc
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\be <
\b<f
\bfs
\bst
\bta
\bab
\bb.
\b.h
\bh>
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The file f
\bfs
\bst
\bta
\bab
\bb contains descriptive information about the various file
systems. f
\bfs
\bst
\bta
\bab
\bb is only read by programs, and not written; it is the duty
of the system administrator to properly create and maintain this file.
Each filesystem is described on a separate line; fields on each line are
separated by tabs or spaces. The order of records in f
\bfs
\bst
\bta
\bab
\bb is important
because fsck(8), mount(8), and umount(8) sequentially iterate through
f
\bfs
\bst
\bta
\bab
\bb doing their thing.
The first field, (_
\bf_
\bs_
\b__
\bs_
\bp_
\be_
\bc), describes the block special device or remote
filesystem to be mounted. For filesystems of type _
\bu_
\bf_
\bs, 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
The second field, (_
\bf_
\bs_
\b__
\bf_
\bi_
\bl_
\be), describes the mount point for the filesys-
tem. For swap partitions, this field should be specified as ``none''.
The third field, (_
\bf_
\bs_
\b__
\bv_
\bf_
\bs_
\bt_
\by_
\bp_
\be), describes the type of the filesystem. The
system currently supports four types of filesystems:
_
\bu_
\bf_
\bs a local UNIX filesystem
_
\bm_
\bf_
\bs a local memory-based UNIX filesystem
_
\bn_
\bf_
\bs a Sun Microsystems compatible ``Network File System''
_
\bs_
\bw_
\ba_
\bp a disk partition to be used for swapping
The fourth field, (_
\bf_
\bs_
\b__
\bm_
\bn_
\bt_
\bo_
\bp_
\bs), describes the mount options associated
with the filesystem. It is formatted as a comma separated list of op-
tions. It contains at least the type of mount (see _
\bf_
\bs_
\b__
\bt_
\by_
\bp_
\be below) plus
any additional options appropriate to the filesystem type.
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 _
\bq_
\bu_
\bo_
\bt_
\ba_
\b._
\bu_
\bs_
\be_
\br and
_
\bq_
\bu_
\bo_
\bt_
\ba_
\b._
\bg_
\br_
\bo_
\bu_
\bp which are located at the root of the associated filesystem.
These defaults may be overridden by putting an equal sign and an alterna-
tive absolute pathname following the quota option. Thus, if the user
quota file for _
\b/_
\bt_
\bm_
\bp is stored in _
\b/_
\bv_
\ba_
\br_
\b/_
\bq_
\bu_
\bo_
\bt_
\ba_
\bs_
\b/_
\bt_
\bm_
\bp_
\b._
\bu_
\bs_
\be_
\br, this location can
userquota=/var/quotas/tmp.user
The type of the mount is extracted from the _
\bf_
\bs_
\b__
\bm_
\bn_
\bt_
\bo_
\bp_
\bs field and stored
separately in the _
\bf_
\bs_
\b__
\bt_
\by_
\bp_
\be field (it is not deleted from the _
\bf_
\bs_
\b__
\bm_
\bn_
\bt_
\bo_
\bp_
\bs
field). If _
\bf_
\bs_
\b__
\bt_
\by_
\bp_
\be is ``rw'' or ``ro'' then the filesystem whose name is
given in the _
\bf_
\bs_
\b__
\bf_
\bi_
\bl_
\be field is normally mounted read-write or read-only on
the specified special file. If _
\bf_
\bs_
\b__
\bt_
\by_
\bp_
\be is ``sw'' then the special file
is made available as a piece of swap space by the swapon(8) command at
the end of the system reboot procedure. The fields other than _
\bf_
\bs_
\b__
\bs_
\bp_
\be_
\bc
and _
\bf_
\bs_
\b__
\bt_
\by_
\bp_
\be are unused. If _
\bf_
\bs_
\b__
\bt_
\by_
\bp_
\be is specified as ``xx'' the entry is
ignored. This is useful to show disk partitions which are currently un-
The fifth field, (_
\bf_
\bs_
\b__
\bf_
\br_
\be_
\bq), 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 will assume
that the filesystem does not need to be dumped.
The sixth field, (_
\bf_
\bs_
\b__
\bp_
\ba_
\bs_
\bs_
\bn_
\bo), 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 _
\bf_
\bs_
\b__
\bp_
\ba_
\bs_
\bs_
\bn_
\bo of 1, and other filesys-
tems should have a _
\bf_
\bs_
\b__
\bp_
\ba_
\bs_
\bs_
\bn_
\bo of 2. Filesystems within a drive will be
checked sequentially, but filesystems 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 zero, a value of zero is returned and
fsck will assume that the filesystem does not need to be checked.
#define FSTAB_RW "rw" /* read-write device */
#define FSTAB_RO "ro" /* read-only device */
#define FSTAB_SW "sw" /* swap device */
#define FSTAB_XX "xx" /* ignore totally */
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 dump */
The proper way to read records from _
\bf_
\bs_
\bt_
\ba_
\bb is to use the routines
getfsent(3), getfsspec(3), getfstype(3), and getfsfile(3).
/etc/fstab The file f
\bfs
\bst
\bta
\bab
\bb resides in _
\b/_
\be_
\bt_
\bc.
S
\bSE
\bEE
\bE A
\bAL
\bLS
\bSO
\bO
H
\bHI
\bIS
\bST
\bTO
\bOR
\bRY
\bY
The f
\bfs
\bst
\bta
\bab
\bb file format appeared in 4.0BSD.
4th Berkeley Distribution June 5, 1993 2
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