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NAME | SYNOPSIS | DESCRIPTION | FILES | NOTES | HISTORY | SEE ALSO | AVAILABILITY | COLOPHON |
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FSTAB(5) File Formats FSTAB(5)
fstab - static information about the filesystems
/etc/fstab
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 fsck(8), mount(8),
and umount(8) sequentially iterate through fstab 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 are ignored.
The following is a typical example of an fstab entry:
LABEL=t-home2 /home ext4 defaults,auto_da_alloc
0 2
The first field (fs_spec).
This field describes the block special device, remote
filesystem or filesystem image for loop device to be
mounted or swap file or swap partition to be enabled.
For ordinary mounts, it will hold (a link to) a block
special device node (as created by mknod(2)) 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 like
e2label(8), xfs_admin(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).
See mount(8), blkid(8) or lsblk(8) for more details about
device identifiers.
Note that mount(8) uses UUIDs as strings. The string
representation of the UUID should be based on lower case
characters.
The second field (fs_file).
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 (fs_vfstype).
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(8).
An entry swap denotes a file or partition to be used for
swapping, cf. swapon(8). An entry none is useful for bind
or move mounts.
More than one type may be specified in a comma-separated
list.
mount(8) and umount(8) support filesystem subtypes. The
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 (fs_mntops).
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 or rw), plus any
additional options appropriate to the filesystem type
(including performance-tuning options). For details, see
mount(8) or swapon(8).
Basic filesystem-independent options are:
defaults
use default options: rw, suid, dev, exec, auto,
nouser, and async.
noauto do not mount when "mount -a" is given (e.g., at
boot time)
user allow a user to mount
owner allow device owner to mount
comment
or x-<name> for use by fstab-maintaining programs
nofail do not report errors for this device if it does not
exist.
The fifth field (fs_freq).
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 (fs_passno).
This field is used by fsck(8) to 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.
/etc/fstab, <fstab.h>
The proper way to read records from fstab is to use the routines
getmntent(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.
getmntent(3), fs(5), findmnt(8), mount(8), swapon(8)
This man page is part of the util-linux package and is available
from https://www.kernel.org/pub/linux/utils/util-linux/.
This page is part of the util-linux (a random collection of Linux
utilities) project. Information about the project can be found
at ⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩. If you
have a bug report for this manual page, send it to
util-linux@vger.kernel.org. This page was obtained from the
project's upstream Git repository
⟨git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git⟩ on
2020-12-18. (At that time, the date of the most recent commit
that was found in the repository was 2020-12-17.) If you
discover any rendering problems in this HTML version of the page,
or you believe there is a better or more up-to-date source for
the page, or you have corrections or improvements to the
information in this COLOPHON (which is not part of the original
manual page), send a mail to man-pages@man7.org
util-linux February 2015 FSTAB(5)
Pages that refer to this page: quota(1), getfsent(3), getmntent(3), crypttab(5), lxc.container.conf(5), nfs(5), proc(5), systemd.automount(5), systemd.mount(5), systemd.swap(5), bootparam(7), dracut.cmdline(7), kernel-command-line(7), systemd.generator(7), e2mmpstatus(8), findmnt(8), fsck(8@@e2fsprogs), fsck(8), fsck.btrfs(8), fsck.xfs(8), mount(8), quotacheck(8), quotaon(8), swapon(8), systemd-fstab-generator(8), systemd-gpt-auto-generator(8), systemd-hibernate-resume-generator(8), systemd-makefs@.service(8), systemd-remount-fs.service(8), xfs_fsr(8)
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