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 various file systems.  fstab is
       only read by programs, and not written; it is the duty  of  the  system  administrator  to
       properly  create and maintain this file.  Each filesystem is described on a separate line;
       fields on each line are separated by tabs or spaces.  Lines starting  with  '#'  are  com‐
       ments,  blank  lines  are  ignored.  The  order  of  records in fstab is important because
       fsck(8), mount(8), and umount(8) sequentially iterate through fstab doing their thing.

       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  cre‐
              ated  by  mknod(8)) for the device to be mounted, like `/dev/cdrom' or `/dev/sdb7'.
              For NFS mounts one will have <host>:<dir>, e.g., `knuth.aeb.nl:/'.  For procfs, use
              `proc'.

              Instead of giving the device explicitly, one may indicate the filesystem that is to
              be mounted by  its  UUID  or  LABEL  (cf.   e2label(8)  or  xfs_admin(8)),  writing
              LABEL=<label>  or UUID=<uuid>, e.g., `LABEL=Boot' or `UUID=3e6be9de-8139-11d1-9106‐
              -a43f08d823a6'.

              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 devices 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 lots of filesystem
              types, such as adfs, affs, autofs, coda, coherent, cramfs, devpts, efs, ext2, ext3,
              hfs, hpfs, iso9660, jfs, minix, msdos, ncpfs,  nfs,  ntfs,  proc,  qnx4,  reiserfs,
              romfs, smbfs, sysv, tmpfs, udf, ufs, umsdos, vfat, xenix, xfs, and possibly others.
              For more details, see mount(8).

              For the filesystems currently supported by the running kernel,  see  /proc/filesys‐
              tems.

              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.

              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 nota‐
              tion rather than add any prefix to the first fstab field (for example  'sshfs#exam‐
              ple.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 plus any additional options appropriate to the filesystem  type.  For
              documentation  on  the available mount options, see mount(8).  For documentation on
              the available swap options, see swapon(8).

              Basic file system 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 for these filesystems by the dump(8) command to determine  which
              filesystems  need to be dumped.  If the fifth field is not present, a value of zero
              is returned and dump will assume that the filesystem does not need to be dumped.

       The sixth field (fs_passno).
              This field is used by the fsck(8) program to determine the order in which  filesys‐
              tem checks are done at reboot time.  The root filesystem should be specified with a
              fs_passno of 1, and 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.
              If  the  sixth  field  is not present or zero, a value of zero is returned and fsck
              will assume that the filesystem does not need to be checked.


NOTES
       The proper way to read records from fstab is to use the routines getmntent(3) or libmount.

       The keyword ignore as filesystem type (3rd field) is not more supported by the  pure  lib‐
       mount 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                                 August 2010                                   FSTAB(5)