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, 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.  But when specifying the volume ID of FAT or NTFS file
              systems upper case characters are used (e.g UUID="A40D-85E7" or
              UUID="61DB7756DB7779B3").

       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.


FILES
       /etc/fstab, <fstab.h>


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).

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

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

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)