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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 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 impor-
       tant  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 filesys-
              tem 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 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 parti-
              tions identifiers are supported for GUID Partition  Table  (GPT)
              and MAC partition table only.
              See  blkid(8) or lsblk(8) for more details about devices identi-
              fiers.

              Note that mount(8) uses UUIDs as strings. The string representa-
              tion 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/filesystems.
              An entry swap denotes a file or partition to be used  for  swap-
              ping,  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 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 con-
              tains 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 filesystem 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 getmn-
       tent(3) or libmount.
       The keyword ignore as filesystem type (3rd field) is not more 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.kernel.org/pub/linux/utils/util-linux/.

util-linux                        August 2010                         FSTAB(5)