fstab manpage

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FSTAB(5)			 File Formats			      FSTAB(5)

       fstab - static information about the filesystems


       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

	      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-

	      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-

	      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

	      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

       The fourth field (fs_mntops).
	      This field describes  the	 mount	options	 associated  with  the

	      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:

		     use  default  options: rw, suid, dev, exec, auto, nouser,
		     and async.

	      noauto do not mount when "mount -a"  is  given  (e.g.,  at  boot

	      user   allow a user to mount

	      owner  allow device owner to mount

		     or x-<name> for use by fstab-maintaining programs

	      nofail do	 not  report  errors  for  this	 device if it does not

       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.

       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).

       /etc/fstab, <fstab.h>

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

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

       This  man  page is part of the util-linux package and is available from

util-linux			  August 2010			      FSTAB(5)