FSTAB(5)						     Linux Programmer's Manual							  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 comments, 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, though at  boot  time  mountall(8)
       may process the file out-of-order when it believes it is safe to do so.

       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 one will have <host>:<dir>, e.g., `knuth.aeb.nl:/'.	For procfs, use `proc'.

	      Instead of giving the device explicitly, one may indicate the (ext2 or xfs) filesystem that is to be mounted by its UUID	or  volume
	      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'.  This will make the system more robust: adding or removing a SCSI disk changes the disk  device  name  but  not  the
	      filesystem volume label.

	      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 `40'.

       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,  coher-
	      ent,  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 swapping, cf. swapon(8).  An entry ignore causes the line  to  be  ignored.
	      This is useful to show disk partitions which are currently unused.  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  deprea-
	      cated).

       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 appropri-
	      ate 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
		     for use by fstab-maintaining programs

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

       The  mountall(8)  program  that	mounts filesystem during boot also recognises additional options that the ordinary mount(8) tool does not.
       These are: ``bootwait'' which can be applied to remote filesystems mounted outside of /usr or /var, without  which  mountall(8)	would  not
       hold up the boot for these; ``nobootwait'' which can be applied to non-remote filesystems to explicitly instruct mountall(8) not to hold up
       the boot for them; ``optional'' which causes the entry to be ignored if the filesystem type is not known at boot time; and  ``showthrough''
       which permits a mountpoint to be mounted before its parent mountpoint (this latter should be used carefully, as it can cause boot hangs).

       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 getmntent(3) or libmount.

FILES

       /etc/fstab, <fstab.h>

SEE ALSO

       mount(8), mountall(8), swapon(8), fs(5), nfs(5), xfs(5), proc(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/.

Linux 2.6							    August 2010 							  FSTAB(5)