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NAME    [Toc]    [Back]

       mount - mount a file system

SYNOPSIS    [Toc]    [Back]

       mount [-lhV]

       mount -a [-fFnrsvw] [-t vfstype]
       mount [-fnrsvw] [-o options [,...]] device | dir
       mount [-fnrsvw] [-t vfstype] [-o options] device dir

DESCRIPTION    [Toc]    [Back]

       All files accessible in a Unix system are arranged in one big tree, the
       file hierarchy, rooted at /.  These files can be spread out  over  several
  devices. The mount command serves to attach the file system found
       on some device to the big file tree. Conversely, the umount(8)  command
       will detach it again.

       The standard form of the mount command, is
	      mount -t type device dir
       This  tells the kernel to attach the file system found on device (which
       is of type type) at the directory dir.  The previous contents (if  any)
       and  owner  and	mode of dir become invisible, and as long as this file
       system remains mounted, the pathname dir refers to the root of the file
       system on device.

       Three forms of invocation do not actually mount anything:
	      mount -h
       prints a help message;
	      mount -V
       prints a version string; and just
	      mount [-l] [-t type]
       lists  all mounted file systems (of type type).	The option -l adds the
       (ext2, ext3 and XFS) labels in this listing.  See below.

       Since Linux 2.4.0 it is possible to remount part of the file  hierarchy
       somewhere else. The call is
	      mount --bind olddir newdir

       The  proc file system is not associated with a special device, and when
       mounting it, an arbitrary keyword, such as proc can be used instead  of
       a  device specification.  (The customary choice none is less fortunate:
       the error message `none busy' from umount can be confusing.)

       Most devices are indicated by a file name (of a block special  device),
       like  /dev/sda1, but there are other possibilities. For example, in the
       case of an NFS mount, device may look like  knuth.cwi.nl:/dir.	It  is
       possible  to  indicate a block special device using its volume label or
       UUID (see the -L and -U options below).

       The file /etc/fstab (see fstab(5)), may contain lines  describing  what
       devices	are  usually  mounted where, using which options. This file is
       used in three ways:

       (i) The command
	      mount -a [-t type]
       (usually given in a bootscript) causes all file	systems  mentioned  in
       fstab (of the proper type) to be mounted as indicated, except for those
       whose line contains the noauto keyword. Adding the -F option will  make
       mount fork, so that the filesystems are mounted simultaneously.

       (ii)  When  mounting  a	file system mentioned in fstab, it suffices to
       give only the device, or only the mount point.

       (iii) Normally, only the superuser can mount  file  systems.   However,
       when  fstab  contains the user option on a line, then anybody can mount
       the corresponding system.

       Thus, given a line
	      /dev/cdrom  /cd  iso9660	ro,user,noauto,unhide
       any user can mount the iso9660 file system found on his CDROM using the
	      mount /dev/cdrom
	      mount /cd
       For  more details, see fstab(5).  Only the user that mounted a filesystem
 can unmount it again.  If any user should be able to unmount,  then
       use users instead of user in the fstab line.  The owner option is similar
 to the user option, with the restriction that the user must be  the
       owner  of  the  special	file. This may be useful e.g. for /dev/fd if a
       login script makes the console user owner of this device.

       The programs mount and umount maintain a list of currently mounted file
       systems	in  the  file  /etc/mtab.  If no arguments are given to mount,
       this list is printed.  When the proc  filesystem  is  mounted  (say  at
       /proc),	the  files  /etc/mtab  and /proc/mounts have very similar contents.
 The former has somewhat more  information,  such	as  the  mount
       options	used,  but  is	not  necessarily up-to-date (cf. the -n option
       below). It is possible to replace  /etc/mtab  by  a  symbolic  link  to
       /proc/mounts,  but some information is lost that way, and in particular
       working with the loop device will be less convenient.

OPTIONS    [Toc]    [Back]

       The full set of options used by an invocation of mount is determined by
       first  extracting the options for the file system from the fstab table,
       then applying any options specified by the  -o  argument,  and  finally
       applying a -r or -w option, when present.

       Options available for the mount command:

       -V     Output version.

       -h     Print a help message.

       -v     Verbose mode.

       -p num If  the  mount requires a passphrase to be entered, read it from
	      file descriptor num instead of from the terminal.

       -a     Mount all filesystems (of the given types) mentioned in fstab.

       -F     (Used in conjunction with -a.)  Fork off a  new  incarnation  of
	      mount  for  each	device.   This will do the mounts on different
	      devices or different NFS servers	in  parallel.	This  has  the
	      advantage that it is faster; also NFS timeouts go in parallel. A
	      disadvantage is that the mounts are  done  in  undefined	order.
	      Thus,  you cannot use this option if you want to mount both /usr
	      and /usr/spool.

       -f     Causes everything to be done except for the actual system  call;
	      if  it's	not  obvious, this ``fakes'' mounting the file system.
	      This option is useful in conjunction with the -v flag to	determine
 what the mount command is trying to do. It can also be used
	      to add entries for devices that were mounted earlier with the -n

       -l     Add  the	ext2,  ext3  and XFS labels in the mount output. Mount
	      must have permission to read the disk device (e.g. be suid root)
	      for  this  to  work.   One can set such a label for ext2 or ext3
	      using the e2label(8) utility, or for XFS using xfs_admin(8).

       -n     Mount without writing in /etc/mtab.  This is necessary for example
 when /etc is on a read-only file system.

       -s     Tolerate	sloppy	mount  options	rather than failing. This will
	      ignore mount options not supported by a filesystem type. Not all
	      filesystems  support this option. This option exists for support
	      of the Linux autofs-based automounter.

       -r     Mount the file system read-only. A synonym is -o ro.

       -w     Mount the file system read/write. This is the default. A synonym
	      is -o rw.

       -L label
	      Mount the partition that has the specified label.

       -U uuid
	      Mount  the  partition  that  has	the specified uuid.  These two
	      options require the file /proc/partitions (present  since  Linux
	      2.1.116) to exist.

       -t vfstype
	      The  argument following the -t is used to indicate the file system
 type.  The file system types which are  currently  supported
	      are:  adfs,  affs,  autofs, coda, coherent, cramfs, devpts, efs,
	      ext, ext2, ext3, hfs, hpfs, iso9660, jfs, minix,	msdos,	ncpfs,
	      nfs, ntfs, proc, qnx4, reiserfs, romfs, smbfs, sysv, tmpfs, udf,
	      ufs, umsdos, vfat, xenix, xfs, xiafs.  Note that coherent,  sysv
	      and  xenix  are  equivalent  and that xenix and coherent will be
	      removed at some point in the future -- use sysv  instead.  Since
	      kernel  version 2.1.21 the types ext and xiafs do not exist anymore.

	      For most types all the mount program has to do is issue a simple
	      mount(2)	system call, and no detailed knowledge of the filesystem
 type is required.  For a few types however (like nfs, smbfs,
	      ncpfs)  ad  hoc  code is necessary. The nfs ad hoc code is built
	      in, but smbfs and ncpfs have a separate mount program. In  order
	      to  make	it possible to treat all types in a uniform way, mount
	      will execute the program /sbin/mount.TYPE (if that exists)  when
	      called  with  type TYPE.	Since various versions of the smbmount
	      program have different calling conventions, /sbin/mount.smb  may
	      have to be a shell script that sets up the desired call.

	      The  type  iso9660 is the default.  If no -t option is given, or
	      if the auto type is specified, the superblock is probed for  the
	      filesystem  type (adfs, bfs, cramfs, ext, ext2, ext3, hfs, hpfs,
	      iso9660, jfs, minix, ntfs, qnx4,	reiserfs,  romfs,  ufs,  vxfs,
	      xfs,  xiafs are supported).  If this probe fails, mount will try
	      to read the file /etc/filesystems, or, if that does  not	exist,
	      /proc/filesystems.   All	of  the  filesystem types listed there
	      will be tried, except for those that are labeled "nodev"	(e.g.,
	      devpts, proc and nfs).

	      Note that the auto type may be useful for user-mounted floppies.
	      Creating a file /etc/filesystems can be  useful  to  change  the
	      probe  order  (e.g.,  to	try vfat before msdos) or if you use a
	      kernel module autoloader.  Warning: the probing uses a heuristic
	      (the  presence  of appropriate `magic'), and could recognize the
	      wrong filesystem type.

	      More than one type may be specified in a comma  separated  list.
	      The list of file system types can be prefixed with no to specify
	      the file system types on which no action should be taken.  (This
	      can be meaningful with the -a option.)

	      For example, the command:
		     mount -a -t nomsdos,ext
	      mounts all file systems except those of type msdos and ext.

       -o     Options  are  specified with a -o flag followed by a comma separated
 string of options.	Some of these options are only	useful
	      when  they appear in the /etc/fstab file.  The following options
	      apply to any file system that is being mounted  (but  not  every
	      file  system  actually honors them - e.g., the sync option today
	      has effect only for ext2, ext3 and ufs):

	      async  All I/O to the file system should be done asynchronously.

	      atime  Update  inode  access  time  for each access. This is the

	      auto   Can be mounted with the -a option.

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

	      dev    Interpret	character or block special devices on the file

	      exec   Permit execution of binaries.

		     Do not update inode access  times	on  this  file	system
		     (e.g,  for  faster  access  on the news spool to speed up
		     news servers).

	      noauto Can only be mounted explicitly (i.e., the -a option  will
		     not cause the file system to be mounted).

	      nodev  Do  not  interpret  character or block special devices on
		     the file system.

	      noexec Do not allow execution of any  binaries  on  the  mounted
		     file  system.   This  option might be useful for a server
		     that has file systems containing binaries	for  architectures
 other than its own.

	      nosuid Do  not allow set-user-identifier or set-group-identifier
		     bits to take effect. (This seems safe,  but  is  in  fact
		     rather unsafe if you have suidperl(1) installed.)

	      nouser Forbid  an  ordinary  (i.e.,  non-root) user to mount the
		     file system.  This is the default.

		     Attempt to remount an already-mounted file system.   This
		     is  commonly  used  to  change the mount flags for a file
		     system, especially to make a readonly file system	writeable.
 It does not change device or mount point.

	      ro     Mount the file system read-only.

	      rw     Mount the file system read-write.

	      suid   Allow set-user-identifier or set-group-identifier bits to
		     take effect.

	      sync   All I/O to the file system should be done	synchronously.

	      user   Allow  an	ordinary  user	to mount the file system.  The
		     name of the mounting user is written to mtab so  that  he
		     can  unmount  the file system again.  This option implies
		     the options noexec, nosuid, and nodev (unless  overridden
		     by   subsequent   options,   as   in   the   option  line

	      users  Allow every user to mount and unmount  the  file  system.
		     This option implies the options noexec, nosuid, and nodev
		     (unless overridden  by  subsequent  options,  as  in  the
		     option line users,exec,dev,suid).

		     Specifies	an  encryption algorithm to use.  Used in conjunction
 with the loop option.

		     Specifies the key size to use  for  an  encryption  algorithm.
  Used  in conjunction with the loop and encryption


       The following options apply only to certain file systems.  We sort them
       by file system. They all follow the -o flag.

Mount options for adfs    [Toc]    [Back]

       uid=value and gid=value
	      Set  the	owner  and  group  of  the  files  in  the file system
	      (default: uid=gid=0).

       ownmask=value and othmask=value
	      Set the permission mask for ADFS 'owner' permissions and 'other'
	      permissions,  respectively  (default:  0700  and	0077,  respectively).
	  See	 also	 /usr/src/linux/Documentation/filesys-

Mount options for affs    [Toc]    [Back]

       uid=value and gid=value
	      Set the owner and group of the root of the file system (default:
	      uid=gid=0, but with option uid or gid without  specified	value,
	      the uid and gid of the current process are taken).

       setuid=value and setgid=value
	      Set the owner and group of all files.

	      Set the mode of all files to value & 0777 disregarding the original
 permissions.  Add search  permission  to  directories  that
	      have read permission.  The value is given in octal.

	      Do not allow any changes to the protection bits on the file system.

       usemp  Set uid and gid of the root of the file system to  the  uid  and
	      gid  of  the mount point upon the first sync or umount, and then
	      clear this option. Strange...

	      Print an informational message for each successful mount.

	      Prefix used before volume name, when following a link.

	      Prefix (of length at most 30) used before '/' when  following  a
	      symbolic link.

	      (Default:  2.)  Number  of  unused  blocks  at  the start of the

	      Give explicitly the location of the root block.

	      Give blocksize. Allowed values are 512, 1024, 2048, 4096.

       grpquota / noquota / quota / usrquota
	      These options are accepted but ignored.  (However, quota	utilities
 may react to such strings in /etc/fstab.)

Mount options for coherent    [Toc]    [Back]


Mount options for devpts    [Toc]    [Back]

       The  devpts  file system is a pseudo file system, traditionally mounted
       on /dev/pts.  In order to acquire a pseudo terminal,  a	process  opens
       /dev/ptmx;  the number of the pseudo terminal is then made available to
       the  process  and  the  pseudo  terminal  slave	can  be  accessed   as

       uid=value and gid=value
	      This  sets  the  owner or the group of newly created PTYs to the
	      specified values. When nothing is specified, they will be set to
	      the  UID and GID of the creating process.  For example, if there
	      is a tty group with GID 5, then gid=5 will cause	newly  created
	      PTYs to belong to the tty group.

	      Set  the mode of newly created PTYs to the specified value.  The
	      default is 0600.	A value of mode=620 and gid=5 makes  "mesg  y"
	      the default on newly created PTYs.

Mount options for ext    [Toc]    [Back]

       None.   Note  that  the	`ext'  file  system is obsolete. Don't use it.
       Since Linux version 2.1.21 extfs  is  no  longer  part  of  the	kernel

Mount options for ext2    [Toc]    [Back]

       The  `ext2'  file  system  is the standard Linux file system.  Due to a
       kernel bug, it may be mounted with random mount options (fixed in Linux

       bsddf / minixdf
	      Set the behaviour for the statfs system call. The minixdf behaviour
 is to return in the f_blocks  field	the  total  number  of
	      blocks  of  the file system, while the bsddf behaviour (which is
	      the default) is to subtract the overhead blocks used by the ext2
	      file system and not available for file storage. Thus

       % mount /k -o minixdf; df /k; umount /k
       Filesystem   1024-blocks  Used Available Capacity Mounted on
       /dev/sda6      2630655	86954  2412169	    3%	 /k
       % mount /k -o bsddf; df /k; umount /k
       Filesystem   1024-blocks  Used Available Capacity Mounted on
       /dev/sda6      2543714	   13  2412169	    0%	 /k

       (Note  that this example shows that one can add command line options to
       the options given in /etc/fstab.)

       check / check=normal / check=strict
	      Set checking level. When at least one of these  options  is  set
	      (and  check=normal is set by default) the inodes and blocks bitmaps
 are checked upon mount (which can take half a minute or  so
	      on  a  big  disk, and is rather useless).  With strict checking,
	      block deallocation checks that the block to free is in the  data

       check=none / nocheck
	      No  checking is done. This is fast. Recent kernels do not have a
	      check option anymore - checking with e2fsck(8) is more  meaningful.

       debug  Print debugging info upon each (re)mount.

       errors=continue / errors=remount-ro / errors=panic
	      Define  the  behaviour  when  an	error is encountered.  (Either
	      ignore errors and just mark the file system erroneous  and  continue,
  or  remount the file system read-only, or panic and halt
	      the system.)  The default is set in the  filesystem  superblock,
	      and can be changed using tune2fs(8).

       grpid or bsdgroups / nogrpid or sysvgroups
	      These  options  define  what group id a newly created file gets.
	      When grpid is set, it takes the group id	of  the  directory  in
	      which  it is created; otherwise (the default) it takes the fsgid
	      of the current process, unless the directory has the setgid  bit
	      set,  in	which case it takes the gid from the parent directory,
	      and also gets the setgid bit set if it is a directory itself.

       resgid=n and resuid=n
	      The ext2 file system reserves a certain percentage of the available
 space (by default 5%, see mke2fs(8) and tune2fs(8)).  These
	      options determine who can use the  reserved  blocks.   (Roughly:
	      whoever  has  the  specified  uid,  or  belongs to the specified

       sb=n   Instead of block 1, use block n as  superblock.  This  could  be
	      useful  when  the filesystem has been damaged.  (Earlier, copies
	      of the superblock would be made every 8192 blocks: in  block  1,
	      8193,  16385,  ...  (and	one  got hundreds or even thousands of
	      copies on a big filesystem). Since version 1.08, mke2fs has a -s
	      (sparse  superblock)  option  to	reduce	the  number  of backup
	      superblocks, and since version 1.15 this is  the	default.  Note
	      that  this  may  mean  that ext2 filesystems created by a recent
	      mke2fs cannot be mounted r/w under Linux 2.0.*.)	The block number
  here  uses 1k units. Thus, if you want to use logical block
	      32768 on a filesystem with 4k blocks, use "sb=131072".

       grpquota / noquota / quota / usrquota
	      These options are accepted but ignored.

	      Disables 32-bit UIDs and GIDs.   This  is  for  interoperability
	      with older kernels which only store and expect 16-bit values.

Mount options for ext3    [Toc]    [Back]

       The  `ext3'  file  system  is version of the ext2 file system which has
       been enhanced with journalling.	It supports the same options  as  ext2
       as well as the following additions:

	      Update the ext3 file system's journal to the current format.

	      When  a  journal	already exists, this option is ignored. Otherwise,
 it specifies the number of the inode which will  represent
	      the  ext3  file  system's  journal file;	ext3 will create a new
	      journal, overwriting the old contents of the  file  whose  inode
	      number is inum.

       noload Do not load the ext3 file system's journal on mounting.

       data=journal / data=ordered / data=writeback
	      Specifies  the  journalling  mode  for  file  data.  Metadata is
	      always journaled.

		     All data is committed into the  journal  prior  to  being
		     written into the main file system.

		     This  is  the  default mode.  All data is forced directly
		     out to the main file system prior to its  metadata  being
		     committed to the journal.

		     Data ordering is not preserved - data may be written into
		     the main file system after its metadata has been  committed
  to the journal.  This is rumoured to be the highestthroughput
 option.  It guarantees	internal  file	system
		     integrity,  however  it  can  allow old data to appear in
		     files after a crash and journal recovery.

Mount options for fat    [Toc]    [Back]

       (Note: fat is not a separate filesystem,  but  a  common  part  of  the
       msdos, umsdos and vfat filesystems.)

       blocksize=512 / blocksize=1024 / blocksize=2048
	      Set blocksize (default 512).

       uid=value and gid=value
	      Set  the owner and group of all files. (Default: the uid and gid
	      of the current process.)

	      Set the umask (the bitmask  of  the  permissions	that  are  not
	      present).  The default is the umask of the current process.  The
	      value is given in octal.

	      Three different levels of pickyness can be chosen:

		     Upper and lower case are accepted	and  equivalent,  long
		     name   parts  are	truncated  (e.g.   verylongname.foobar
		     becomes verylong.foo), leading and  embedded  spaces  are
		     accepted in each name part (name and extension).

		     Like  "relaxed",  but  many  special characters (*, ?, <,
		     spaces, etc.) are rejected.  This is the default.

		     Like "normal", but names may not contain long  parts  and
		     special  characters that are sometimes used on Linux, but
		     are not accepted by MS-DOS are rejected. (+,  =,  spaces,

	      Sets  the codepage for converting to shortname characters on FAT
	      and VFAT filesystems. By default, codepage 437 is used.

       conv=b[inary] / conv=t[ext] / conv=a[uto]
	      The fat file system can perform CRLF<-->NL (MS-DOS  text	format
	      to  UNIX	text  format)  conversion in the kernel. The following
	      conversion modes are available:

	      binary no translation is performed.  This is the default.

	      text   CRLF<-->NL translation is performed on all files.

	      auto   CRLF<-->NL translation is performed  on  all  files  that
		     don't  have  a "well-known binary" extension. The list of
		     known  extensions	can  be  found	at  the  beginning  of
		     fs/fat/misc.c  (as  of  2.0,  the list is: exe, com, bin,
		     app, sys, drv, ovl, ovr, obj, lib, dll,  pif,  arc,  zip,
		     lha,  lzh,  zoo, tar, z, arj, tz, taz, tzp, tpz, gz, tgz,
		     deb, gif, bmp, tif, gl, jpg, pcx, tfm, vf, gf,  pk,  pxl,

	      Programs	that do computed lseeks won't like in-kernel text conversion.
	Several people have had  their	data  ruined  by  this
	      translation. Beware!

	      For  file  systems  mounted  in  binary  mode, a conversion tool
	      (fromdos/todos) is available.

	      Forces the driver to use the CVF (Compressed Volume File) module
	      cvf_module  instead  of  auto-detection.	If the kernel supports
	      kmod, the cvf_format=xxx option also controls on-demand CVF module

	      Option passed to the CVF module.

       debug  Turn  on	the  debug  flag.  A version string and a list of file
	      system parameters will be printed (these data are  also  printed
	      if the parameters appear to be inconsistent).

       fat=12 / fat=16 / fat=32
	      Specify  a  12,  16 or 32 bit fat.  This overrides the automatic
	      FAT type detection routine.  Use with caution!

	      Character set to use for converting between 8 bit characters and
	      16 bit Unicode characters. The default is iso8859-1.  Long filenames
 are stored on disk in Unicode format.

       quiet  Turn on the quiet flag.  Attempts to chown or chmod files do not
	      return errors, although they fail. Use with caution!

       sys_immutable, showexec, dots, nodots, dotsOK=[yes|no]
	      Various misguided attempts to force Unix or DOS conventions onto
	      a FAT file system.

Mount options for hpfs    [Toc]    [Back]

       uid=value and gid=value
	      Set the owner and group of all files. (Default: the uid and  gid
	      of the current process.)

	      Set  the	umask  (the  bitmask  of  the permissions that are not
	      present). The default is the umask of the current process.   The
	      value is given in octal.

       case=lower / case=asis
	      Convert all files names to lower case, or leave them.  (Default:

       conv=binary / conv=text / conv=auto
	      For conv=text, delete some random CRs (in particular,  all  followed
 by NL) when reading a file.  For conv=auto, choose more or
	      less  at	random	between  conv=binary   and   conv=text.    For
	      conv=binary, just read what is in the file. This is the default.

	      Do not abort mounting when certain consistency checks fail.

Mount options for iso9660    [Toc]    [Back]

       Normal iso9660  filenames  appear  in  a  8.3  format  (i.e.,  DOS-like
       restrictions on filename length), and in addition all characters are in
       upper case.  Also there is no field  for  file  ownership,  protection,
       number of links, provision for block/character devices, etc.

       Rock  Ridge  is an extension to iso9660 that provides all of these unix
       like features.  Basically there are extensions to each directory record
       that  supply  all of the additional information, and when Rock Ridge is
       in use, the filesystem is indistinguishable from  a  normal  UNIX  file
       system (except that it is read-only, of course).

       norock Disable the use of Rock Ridge extensions, even if available. Cf.

	      Disable the use of Microsoft Joliet extensions, even  if	available.
 Cf. map.

       check=r[elaxed] / check=s[trict]
	      With  check=relaxed, a filename is first converted to lower case
	      before doing the	lookup.   This	is  probably  only  meaningful
	      together with norock and map=normal.  (Default: check=strict.)

       uid=value and gid=value
	      Give  all  files	in the file system the indicated user or group
	      id, possibly overriding the information found in the Rock  Ridge
	      extensions.  (Default: uid=0,gid=0.)

       map=n[ormal] / map=o[ff] / map=a[corn]
	      For  non-Rock  Ridge volumes, normal name translation maps upper
	      to lower case ASCII, drops a trailing `;1', and converts `;'  to
	      `.'.   With  map=off  no	name  translation is done. See norock.
	      (Default: map=normal.)  map=acorn is like  map=normal  but  also
	      apply Acorn extensions if present.

	      For  non-Rock  Ridge volumes, give all files the indicated mode.
	      (Default: read permission for everybody.)   Since  Linux	2.1.37
	      one  no  longer  needs to specify the mode in decimal. (Octal is
	      indicated by a leading 0.)

       unhide Also show hidden and associated files.

	      Set  the	block  size  to  the   indicated   value.    (Default:

       conv=a[uto] / conv=b[inary] / conv=m[text] / conv=t[ext]
	      (Default:  conv=binary.)	 Since Linux 1.3.54 this option has no
	      effect anymore.  (And non-binary settings used to be  very  dangerous,
 possibly leading to silent data corruption.)

       cruft  If  the high byte of the file length contains other garbage, set
	      this mount option to ignore the high  order  bits  of  the  file
	      length.	This  implies  that a file cannot be larger than 16MB.
	      The `cruft' option is set automatically if the entire CDROM  has
	      a weird size (negative, or more than 800MB). It is also set when
	      volume sequence numbers other than 0 or 1 are seen.

	      Select number of session on multisession CD. (Since 2.3.4.)

	      Session begins from sector xxx. (Since 2.3.4.)

Mount options for minix    [Toc]    [Back]


Mount options for msdos    [Toc]    [Back]

       See mount options for fat.  If the msdos file system detects an	inconsistency,
  it  reports an error and sets the file system read-only. The
       file system can be made writeable again by remounting it.

Mount options for ncp    [Toc]    [Back]

       Just like nfs, the ncp implementation  expects  a  binary  argument  (a
       struct  ncp_mount_data) to the mount system call. This argument is constructed
 by ncpmount(8) and the current version of  mount  (2.6h)  does
       not know anything about ncp.

Mount options for nfs    [Toc]    [Back]

       Instead	of a textual option string, parsed by the kernel, the nfs file
       system expects a binary argument of type  struct  nfs_mount_data.   The
       program	 mount	itself	parses	the  following	options  of  the  form
       `tag=value',  and  puts	them  in  the  structure  mentioned:  rsize=n,
       wsize=n,   timeo=n,   retrans=n,  acregmin=n,  acregmax=n,  acdirmin=n,
       acdirmax=n, actimeo=n, retry=n,	port=n,  mountport=n,  mounthost=name,
       mountprog=n,  mountvers=n,  nfsprog=n, nfsvers=n, namlen=n.  The option
       addr=n is accepted but ignored.	Also the  following  Boolean  options,
       possibly  preceded  by  no  are	recognized:  bg, fg, soft, hard, intr,
       posix, cto, ac, tcp, udp, lock.	For details, see nfs(5).

       Especially useful options include

	      This will make your nfs connection much  faster  than  with  the
	      default  buffer  size  of 1024. (NFSv2 does not work with larger
	      values of rsize and wsize.)

       hard   The program accessing a file on a NFS mounted file  system  will
	      hang  when the server crashes. The process cannot be interrupted
	      or killed unless you also specify intr.  When the NFS server  is
	      back  online the program will continue undisturbed from where it
	      was. This is probably what you want.

       soft   This option allows the kernel to time out if the nfs  server  is
	      not  responding  for  some  time. The time can be specified with
	      timeo=time.  This option might be  useful  if  your  nfs	server
	      sometimes doesn't respond or will be rebooted while some process
	      tries to get a file from the server.   Usually  it  just	causes
	      lots of trouble.

       nolock Do not use locking. Do not start lockd.

Mount options for ntfs    [Toc]    [Back]

	      Character  set  to  use when returning file names.  Unlike VFAT,
	      NTFS suppresses names that contain unconvertible characters.

       utf8   Use UTF-8 for converting file names.

	      For 0 (or `no' or `false'), do  not  use	escape	sequences  for
	      unknown  Unicode	characters.   For 1 (or `yes' or `true') or 2,
	      use vfat-style 4-byte escape sequences starting with ":". Here 2
	      give  a  little-endian  encoding	and  1 a byteswapped bigendian

	      If enabled (posix=1),  the  file	system	distinguishes  between
	      upper  and lower case. The 8.3 alias names are presented as hard
	      links instead of being suppressed.

       uid=value, gid=value and umask=value
	      Set the file permission on  the  filesystem.   By  default,  the
	      files are owned by root and not readable by somebody else.

Mount options for proc    [Toc]    [Back]

       uid=value and gid=value
	      These options are recognized, but have no effect as far as I can

Mount options for reiserfs    [Toc]    [Back]

       The   reiserfs	mount	options   are	more   fully   described    at

       conv   Instructs  version  3.6 reiserfs software to mount a version 3.5
	      file system, using the 3.6 format  for  newly  created  objects.
	      This  file system will no longer be compatible with reiserfs 3.5

       hash=rupasov / hash=tea / hash=r5 / hash=detect
	      Choose which hash function  reiserfs  will  use  to  find  files
	      within directories.

		     A hash invented by Yury Yu. Rupasov.  It is fast and preserves
 locality,  mapping	lexicographically  close  file
		     names  to	close  hash values.  This option should not be
		     used, as it causes a high probability of hash collisions.

	      tea    A	  Davis-Meyer	 function    implemented   by	Jeremy
		     Fitzhardinge.  It uses hash permuting bits in  the  name.
		     It  gets  high randomness and, therefore, low probability
		     of hash collisions at come CPU cost.  This may be used if
		     EHASHCOLLISION errors are experienced with the r5 hash.

	      r5     A	modified  version  of  the rupasov hash. It is used by
		     default and is the best choice unless the file system has
		     huge directories and unusual file-name patterns.

	      detect Instructs	mount  to detect which hash function is in use
		     by examining the file system being mounted,  and to write
		     this  information	into  the reiserfs superblock. This is
		     only useful on the first mount of an old format file system.

	      Tunes the block allocator. This may provide performance improvements
 in some situations.

	      Tunes the block allocator. This may provide performance improvements
 in some situations.

	      Disable  the  border  allocator  algorithm  invented by Yury Yu.
	      Rupasov.	This may provide performance improvements in some situations.

       nolog  Disable	journalling.  This  will  provide  slight  performance
	      improvements in some situations at the cost of losing reiserfs's
	      fast  recovery  from  crashes.  Even with this option turned on,
	      reiserfs still performs all  journalling	operations,  save  for
	      actual  writes  into  its  journalling  area.  Implementation of
	      nolog is a work in progress.

       notail By  default,  reiserfs  stores  small  files  and  `file	tails'
	      directly	into  its  tree.  This confuses some utilities such as
	      LILO(8).	This option is used to disable packing of  files  into
	      the tree.

	      Replay  the  transactions  which	are in the journal, but do not
	      actually mount the file system. Mainly used by reiserfsck.

	      A remount option which permits online expansion of reiserfs partitions.
	 Instructs reiserfs to assume that the device has num-
	      ber blocks.  This option is designed for use with devices  which
	      are  under  logical volume management (LVM).  There is a special
	      resizer	 utility    which     can     be     obtained	  from

Mount options for romfs    [Toc]    [Back]


Mount options for smbfs    [Toc]    [Back]

       Just  like  nfs,  the  smb  implementation expects a binary argument (a
       struct smb_mount_data) to the mount system call. This argument is  constructed
  by  smbmount(8)  and the current version of mount (2.9w) does
       not know anything about smb.

Mount options for sysv    [Toc]    [Back]


Mount options for tmpfs    [Toc]    [Back]

       The following parameters accept a suffix k, m  or  g  for  Ki,  Mi,  Gi
       (binary kilo, mega and giga) and can be changed on remount.

	      Override	default  size of the filesystem.  The size is given in
	      bytes, and rounded down to entire pages.	The default is half of
	      the memory.

	      Set number of blocks.

	      Set number of inodes.

       mode=  Set initial permissions of the root directory.

Mount options for udf    [Toc]    [Back]

       gid=   Set the default group.

       umask= Set the default umask.

       uid=   Set the default user.

       unhide Show otherwise hidden files.

	      Show deleted files in lists.

       strict Set strict conformance (unused).

       utf8   (unused).


       bs=    Set the block size. (May not work unless 2048.)

       novrs  Skip volume sequence recognition.

	      Set the CDROM session counting from 0. Default: last session.

	      Override standard anchor location. Default: 256.

	      Override the VolumeDesc location. (unused)

	      Override the PartitionDesc location. (unused)

	      Set the last block of the filesystem.

	      Override the fileset block location. (unused)

	      Override the root directory location. (unused)

Mount options for ufs    [Toc]    [Back]

	      UFS is a file system widely used in different operating systems.
	      The problem are differences among implementations.  Features  of
	      some  implementations are undocumented, so its hard to recognize
	      the type of ufs automatically.  That's why the user must specify
	      the type of ufs by mount option.	Possible values are:

	      old    Old format of ufs, this is the default, read only.

	      44bsd  For    filesystems   created   by	 a   BSD-like	system

	      sun    For filesystems created by SunOS or Solaris on Sparc.

	      sunx86 For filesystems created by Solaris on x86.

		     For filesystems created by  NeXTStep  (on	NeXT  station)
		     (currently read only).

		     For NextStep CDROMs (block_size == 2048), read-only.

		     For  filesystems  created	by  OpenStep  (currently  read

	      Set behaviour on error:

	      panic  If an error is encountered, cause a kernel panic.

		     These mount options don't do anything at present; when an
		     error is encountered only a console message is printed.

Mount options for umsdos    [Toc]    [Back]

       See mount options for msdos.  The dotsOK option is explicitly killed by

Mount options for vfat    [Toc]    [Back]

       First of all, the mount options for fat	are  recognized.   The	dotsOK
       option is explicitly killed by vfat.  Furthermore, there are

	      Translate   unhandled  Unicode  characters  to  special  escaped
	      sequences.  This lets you backup and restore filenames that  are
	      created  with any Unicode characters. Without this option, a '?'
	      is used when no translation is possible. The escape character is
	      ':'  because it is otherwise illegal on the vfat filesystem. The
	      escape sequence that gets used, where u is the  unicode  character,
 is: ':', (u & 0x3f), ((u>>6) & 0x3f), (u>>12).

       posix  Allow two files with names that only differ in case.

	      First  try  to make a short name without sequence number, before
	      trying name~num.ext.

       utf8   UTF8 is the filesystem safe 8-bit encoding of  Unicode  that  is
	      used  by	the  console.  It can be be enabled for the filesystem
	      with this option.  If `uni_xlate' gets set, UTF8 gets  disabled.

Mount options for xenix    [Toc]    [Back]


Mount options for xfs    [Toc]    [Back]

	      Sets  the  preferred  buffered  I/O  size (default size is 64K).
	      size must be expressed as the logarithm (base2) of  the  desired
	      I/O  size.   Valid  values  for  this  option are 14 through 16,
	      inclusive (i.e. 16K, 32K, and 64K bytes).  On machines with a 4K
	      pagesize,  13  (8K  bytes)  is also a valid size.  The preferred
	      buffered I/O size can also be  altered  on  an  individual  file
	      basis using the ioctl(2) system call.

       dmapi  /  xdsm
	      Enable the DMAPI (Data Management API) event callouts.

	      Set  the	number	of in-memory log buffers.  Valid numbers range
	      from 2-8 inclusive.  The default value is 8 buffers for filesystems
  with  a blocksize of 64K, 4 buffers for filesystems with a
	      blocksize of 32K, 3 buffers for filesystems with a blocksize  of
	      16K, and 2 buffers for all other configurations.	Increasing the
	      number of buffers may increase performance on some workloads  at
	      the  cost  of the memory used for the additional log buffers and
	      their associated control structures.

	      Set the size of each in-memory  log  buffer.   Valid  sizes  are
	      16384  (16K)  and  32768	(32K).	The default value for machines
	      with more than 32MB of memory is 32768, machines with less  memory
 use 16384 by default.

       logdev=device and rtdev=device
	      Use  an external log (metadata journal) and/or real-time device.
	      An XFS filesystem has up to three parts: a data section,	a  log
	      section,	and  a	real-time  section.   The real-time section is
	      optional, and the log section can be separate from the data section
 or contained within it.  Refer to xfs(5).

	      Data  allocations will not be aligned at stripe unit boundaries.

	      Access timestamps are not updated when a file is read.

	      The filesystem will be mounted without running log recovery.  If
	      the  filesystem  was  not  cleanly unmounted, it is likely to be
	      inconsistent when mounted in norecovery  mode.   Some  files  or
	      directories  may not be accessible because of this.  Filesystems
	      mounted norecovery must be mounted read-only or the  mount  will

	      Make  writes  to files opened with the O_SYNC flag set behave as
	      if the O_DSYNC flag had been used instead.  This can  result  in
	      better performance without compromising data safety.  However if
	      this option is in effect, timestamp updates from	O_SYNC	writes
	      can be lost if the system crashes.

       quota / usrquota / uqnoenforce
	      User  disk  quota  accounting  enabled,  and limits (optionally)

       grpquota / gqnoenforce
	      Group disk quota	accounting  enabled  and  limits  (optionally)

       sunit=value and swidth=value
	      Used to specify the stripe unit and width for a RAID device or a
	      stripe volume.  value must be specified in 512-byte block units.
	      If this option is not specified and the filesystem was made on a
	      stripe volume or the stripe width or unit were specified for the
	      RAID  device  at	mkfs  time,  then  the	mount system call will
	      restore the value from the superblock.  For filesystems that are
	      made  directly  on  RAID	devices,  these options can be used to
	      override the information in the  superblock  if  the  underlying
	      disk  layout changes after the filesystem has been created.  The
	      swidth option is required if the sunit option  has  been	specified,
 and must be a multiple of the sunit value.

Mount options for xiafs    [Toc]    [Back]

       None. Although nothing is wrong with xiafs, it is not used much, and is
       not maintained. Probably one shouldn't use  it.	 Since	Linux  version
       2.1.21 xiafs is no longer part of the kernel source.

THE LOOP DEVICE    [Toc]    [Back]

       One  further possible type is a mount via the loop device. For example,
       the command

	 mount /tmp/fdimage /mnt -t msdos -o loop=/dev/loop3,blocksize=1024

       will set up the loop  device  /dev/loop3  to  correspond  to  the  file
       /tmp/fdimage,  and  then mount this device on /mnt.  This type of mount
       knows about three options, namely loop, offset and encryption, that are
       really  options to losetup(8).  If the mount requires a passphrase, you
       will be prompted for one unless you specify a file descriptor  to  read
       from  instead  with the --pass-fd option. If no explicit loop device is
       mentioned (but just an option `-o loop' is given), then mount will  try
       to find some unused loop device and use that.  If you are not so unwise
       as to make /etc/mtab a symbolic link  to  /proc/mounts  then  any  loop
       device allocated by mount will be freed by umount.  You can also free a
       loop device by hand, using `losetup -d', see losetup(8).

FILES    [Toc]    [Back]

       /etc/fstab file system table
       /etc/mtab table of mounted file systems
       /etc/mtab~ lock file
       /etc/mtab.tmp temporary file

SEE ALSO    [Toc]    [Back]

       mount(2), umount(2), fstab(5), umount(8),  swapon(8),  nfs(5),  xfs(5),
       e2label(8),  xfs_admin(8),  mountd(8),  nfsd(8), mke2fs(8), tune2fs(8),

BUGS    [Toc]    [Back]

       It is possible for a corrupted file system to cause a crash.

       Some Linux file systems don't support -o sync (the ext2 and  ext3  file
       systems do support synchronous updates (a la BSD) when mounted with the
       sync option).

       The -o remount may not be able to change mount parameters (all  ext2fs-
       specific  parameters,  except  sb,  are	changeable with a remount, for
       example, but you can't change gid or umask for the fatfs).

HISTORY    [Toc]    [Back]

       A mount command existed in Version 5 AT&T UNIX.

Linux 2.0		       14 September 1997		      MOUNT(8)
[ Back ]
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