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Linux 2.6 - man page for fstab (linux section 5)

FSTAB(5)			    Linux Programmer's Manual				 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 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  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

	      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 `\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-

	      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 parti-
	      tions 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 nota-
	      tion rather than add any prefix to the first fstab field (for example  'sshfs#exam-
	      ple.com' is depreacated).

       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:

		     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

		     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 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.

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

       /etc/fstab, <fstab.h>

       mount(8), mountall(8), swapon(8), fs(5), nfs(5), xfs(5), proc(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 ftp://ftp.ker-

Linux 2.6				   August 2010					 FSTAB(5)

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