fstab(5) - static information about the filesystems

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FSTAB(5)					 File Formats					      FSTAB(5)

NAME
       fstab - static information about the filesystems

SYNOPSIS
       /etc/fstab

DESCRIPTION
       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 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 typi‐
	      cally 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 for the filesystem.	For swap partitions, this field should
	      be  specified  as `none'. If the name of the mount point contains spaces these can be escaped as
	      `\040'.

       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' suf‐
	      fix.  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  perfor‐
	      mance-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.

NOTES
       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).

FILES
       /etc/fstab, <fstab.h>

SEE ALSO
       findmnt(8), mount(8), swapon(8), fs(5), getmntent(3)

HISTORY
       The ancestor of this fstab file format appeared in 4.0BSD.

AVAILABILITY
       This   man   page   is	part   of   the  util-linux  package  and  is  available  from	ftp://ftp.ker‐
       nel.org/pub/linux/utils/util-linux/.

util-linux					 February 2015					      FSTAB(5)