fstab - static information about the filesystems
The file fstab
contains descriptive information about the filesystems the
system can mount. fstab
is only read by programs, and not written; it
is the duty of the system administrator to properly create and maintain this
file. The order of records in fstab
is important because
(8), and umount
(8) sequentially iterate
doing their thing.
Each filesystem is described on a separate line. Fields on each line are
separated by tabs or spaces. Lines starting with '#' are comments. Blank lines
The following is a typical example of an fstab
LABEL=t-home2 /home ext4
defaults,auto_da_alloc 0 2
The first field
This field describes the block special device
or remote filesystem to be mounted.
For ordinary mounts, it will hold (a link to) a block special device node (as
created by mknod
(8)) for the device to be mounted, like `/dev/cdrom' or
`/dev/sdb7'. For NFS mounts, this field is <host>:<dir>, e.g.,
`knuth.aeb.nl:/'. For filesystems with no storage, any string can be used, and
will show up in df
(1) output, for example. Typical usage is `proc' for
procfs; `mem', `none', or `tmpfs' for tmpfs. Other special filesystems, like
udev and sysfs, are typically not listed in fstab
LABEL=<label> or UUID=<uuid> may be given instead of a device name.
This is the recommended method, as device names are often a coincidence of
hardware detection order, and can change when other disks are added or
removed. For example, `LABEL=Boot' or
`UUID=3e6be9de-8139-11d1-9106-a43f08d823a6'. (Use a filesystem-specific tool
(8), or fatlabel
(8) to set
LABELs on filesystems).
It's also possible to use PARTUUID= and PARTLABEL=. These partitions identifiers
are supported for example for GUID Partition Table (GPT).
(8) or lsblk
(8) for more details about
Note that mount
(8) uses UUIDs as strings. The string representation of
the UUID should be based on lower case characters.
The second field
This field describes the mount point (target)
for the filesystem. For swap partitions, this field should be specified as
`none'. If the name of the mount point contains spaces or tabs these can be
escaped as `\040' and '\011' respectively.
The third field
This field describes the type of the
filesystem. Linux supports many filesystem types: ext4, xfs, btrfs, f2fs,
vfat, ntfs, hfsplus, tmpfs, sysfs, proc, iso9660, udf, squashfs, nfs, cifs,
and many more. For more details, see mount
An entry swap
denotes a file or partition to be used for swapping, cf.
(8). An entry none
is useful for bind or move mounts.
More than one type may be specified in a comma-separated list.
(8) and umount
(8) support filesystem subtypes
subtype is defined by '.subtype' suffix. For example 'fuse.sshfs'. It's
recommended to use subtype notation rather than add any prefix to the first
fstab field (for example 'sshfs#example.com' is deprecated).
The fourth field
This field 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 (ro
), plus any additional options
appropriate to the filesystem type (including performance-tuning options). For
details, see mount
(8) or swapon
Basic filesystem-independent options are:
- use default options: rw, suid, dev, exec, auto, nouser, and
- do not mount when "mount -a" is given (e.g., at
- allow a user to mount
- allow device owner to mount
- or x-<name> for use by fstab-maintaining
- do not report errors for this device if it does not
The fifth field
This field is used by dump(8) to
determine which filesystems need to be dumped. Defaults to zero (don't dump)
if not present.
The sixth field
This field is used by fsck
determine the order in which filesystem checks are done at boot time. The root
filesystem should be specified with a fs_passno
of 1. 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 utilize parallelism available in the hardware. Defaults to
zero (don't fsck) if not present.
The proper way to read records from fstab
is to use the routines
(3) or libmount
The keyword ignore
as a filesystem type (3rd field) is no longer
supported by the pure libmount based mount utility (since util-linux v2.22).
The ancestor of this fstab
file format appeared in 4.0BSD.
This man page is part of the util-linux package and is available from