fstab

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 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.


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

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
       https://www.kernel.org/pub/linux/utils/util-linux/.



util-linux                       February 2015                        FSTAB(5)