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\"     @(#)fstab.5      8.1 (Berkeley) 6/5/93
\"
Dd April 19, 2020
Dt FSTAB 5
Os
Sh NAME
Nm fstab
Nd file system table for devices, types, and mount points
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.
Lines beginning
with
Dq #
are comments.
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 respective tasks.
Pp
Each configuration line/record in
Nm
has the format:
Dl fs_spec fs_file fs_vfstype fs_mntops fs_freq fs_passno
Pp
The first field,
Pq Fa fs_spec ,
describes the block special device or
remote file system to be mounted.
For file systems of type
Em 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
Dq r
after the last
Dq /
in the special file name.
(Note that for some file systems, e.g.,
Em kernfs ,
Em procfs ,
and
Em tmpfs ,
this field has no applicable use, and any string may be supplied as a
placeholder.
It is present simply for consistency of argument number and order.)
Pp
If the first field is of the form
Dq NAME=<value>
then all the
Xr dk 4
wedge partitions are searched for one that has a wedge name equal to
Ar <value>
and the device corresponding to it is selected.
Pp
If the first field starts with the prefix
Dq ROOT.
the prefix is replaced with
Dq /dev/[root_device] ,
where
Bq root_device
is the value of the
Dq kern.root_device
sysctl.
Pp
The second field,
Pq Fa fs_file ,
describes the mount point for the file system.
For swap and dump 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 currently supports these file systems:
Bl -tag -width filecore -offset indent
It Em adosfs
an
Tn AmigaDOS
file system.
It Em cd9660
an
Tn ISO
9660 CD-ROM file system.
It Em ext2fs
an implementation of the Linux
Dq Second Extended File-system .
It Em fdesc
an implementation of
Pa /dev/fd .
It Em ffs
a local
Ux
file system.
It Em filecore
a file system for
Tn RISC\ OS .
It Em kernfs
various and sundry kernel statistics.
It Em lfs
a log-structured file-system.
It Em mfs
a local memory-based
Ux
file system.
It Em msdos
an
Tn MS-DOS
Dq FAT file system .
It Em nfs
a Sun Microsystems compatible
Dq Network File System .
It Em ntfs
a file system used by
Tn Windows NT .
Still experimental.
It Em null
a loop-back file system, allowing parts of the system to be viewed
elsewhere.
It Em overlay
a demonstration of layered file systems.
It Em portal
a general file system interface, currently supports TCP and FS mounts.
It Em procfs
a local file system of process information.
It Em ptyfs
a pseudo-terminal device file system.
It Em swap
a disk partition to be used for swapping and paging.
It Em tmpfs
an efficient memory file system.
It Em umap
a user and group re-mapping file system.
It Em union
a translucent file system.
It Em zfs
a ZFS file system.
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.
Pp
The option
Dq auto
can be used in the
Dq noauto
form to cause
a file system not to be mounted automatically (with
Dq mount -a
,
or system boot time).
Pp
If the options
Dq userquota
and/or
Dq groupquota
are specified,
the file system is automatically processed by the
Xr quotacheck 8
command, and legacy 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
It is recommended to turn on the new, in-file system quota with
Xr tunefs 8
or at
Xr newfs 8
time, and to not use the
Dq userquota
or
Dq groupquota
options.
Migration of limits to the new in-file system quota can be handled
via
Xr quotadump 8
and
Xr quotarestore 8 .
Pp
The option
Dq rump
is used to mount the file system using a
Xr rump 3
userspace server instead of the kernel server.
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
Dq rw
or
Dq 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
Dq sw
or
Dq dp
then the special file is made available as a piece of swap
or dump
space by the
Xr swapctl 8
command towards the beginning of the system reboot procedure.
See
Xr swapctl 8
for more information on configuring swap and dump devices.
The fields other than
Fa fs_spec
and
Fa fs_type
are unused.
If
Fa fs_type
is specified as
Dq 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
Xr dump 8
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.
Filesystems within a drive will be checked sequentially,
but file systems 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
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_DP        "dp"    /* dump 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;    /* type of file system */
       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 */
};
Ed
Pp
The proper way to read records from
Pa fstab
is to use the routines
Xr getfsent 3 ,
Xr getfsspec 3 ,
and
Xr getfsfile 3 .
Sh FILES
Bl -tag -width /etc/fstab
It Pa /etc/fstab
The location of
Nm
configuration file.
It Pa /usr/share/examples/fstab/
Some useful configuration examples.
El
Sh EXAMPLES
To use
Dq NAME
on a non-GPT disk, use:
Bd -literal
NAME=sb2k5Root/a        /       ffs     rw,log           1 1
NAME=sb2k5Root/b        none    swap    sw,dp            0 0
Ed
Pp
For a
Xr gpt 8
disk, use:
Bd -literal
NAME=firstpartition     /       ffs     rw,log           1 1
NAME=secondpartition    none    swap    sw,dp            0 0
Ed
Sh SEE ALSO
Xr getfsent 3 ,
Xr getfsspecname 3 ,
Xr mount 8 ,
Xr swapctl 8
Sh HISTORY
The
Nm
file format appeared in
Bx 4.0 .

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