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MOUNT(8)		   Linux Programmer's Manual		      MOUNT(8)

       mount - mount a file system

       mount [-lhV]

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

       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  sev-
       eral  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
       After this call the same	contents is accessible in two places.

       This  call  attaches  only  (part of) a single filesystem, not possible
       submounts. The entire file hierarchy including submounts	is attached  a
       second place using
	      mount --rbind olddir newdir

       Since  Linux  2.5.1  it is possible to atomically move a	subtree	to an-
       other place. The	call is
	      mount --move 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	 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] [-O optlist]
       (usually	 given	in  a bootscript) causes all file systems mentioned in
       fstab (of the proper type and/or	having or not having  the  proper  op-
       tions) 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 filesys-
       tem 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 simi-
       lar 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 lo-
       gin 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 con-
       tents. The former has somewhat more information,	such as	the mount  op-
       tions  used,  but  is not necessarily up-to-date	(cf. the -n option be-
       low). 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.

       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 ap-
       plying a	-r or -w option, when present.

       Options available for the mount command:

       -V     Output version.

       -h     Print a help message.

       -v     Verbose mode.

       -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 de-
	      vices or different NFS servers in	parallel.  This	has the	advan-
	      tage that	it is faster; also NFS timeouts	go in parallel.	A dis-
	      advantage	is that	the mounts are done in undefined order.	 Thus,
	      you cannot use this option if you	want to	mount  both  /usr  and

       -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	deter-
	      mine 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 us-
	      ing the e2label(8) utility, or for XFS using xfs_admin(8).

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

       -s     Tolerate sloppy mount options rather than	failing. This will ig-
	      nore  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  op-
	      tions  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  sys-
	      tem  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,  ramfs,  reiserfs,	 romfs,	 smbfs,	 sysv,
	      tmpfs, udf, ufs, umsdos, vfat, xenix, xfs, xiafs.	 Note that co-
	      herent, sysv and xenix are equivalent and	that xenix and	coher-
	      ent  will	be removed at some point in the	future -- use sysv in-
	      stead. 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  filesys-
	      tem 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, udf, 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).  If	 /etc/filesystems  ends	 in  a
	      line with	a single * only, mount will read /proc/filesystems af-

	      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  filesys-
	      tem  type, possibly with catastrophic consequences. If your data
	      is valuable, don't ask mount to guess.

	      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     Used  in conjunction with	-a, to limit the set of	filesystems to
	      which the	-a is applied.	Like -t	in this	regard except that  it
	      is  useless  except in the context of -a.	 For example, the com-
		     mount -a -O no_netdev
	      mounts all file systems except those which have the option _net-
	      dev specified in the options field in the	/etc/fstab file.

	      It  is different from -t in that each option is matched exactly;
	      a	leading	no at the beginning of one option does not negate  the

	      The  -t  and  -O	options	are cumulative in effect; that is, the
		     mount -a -t ext2 -O _netdev
	      mounts all ext2 filesystems with the  _netdev  option,  not  all
	      filesystems  that	 are  either  ext2  or have the	_netdev	option

       -o     Options are specified with a -o flag followed by a  comma	 sepa-
	      rated  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 de-

	      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.

		     The filesystem resides on a device	that requires  network
		     access  (used  to	prevent	 the system from attempting to
		     mount these filesystems until the network	has  been  en-
		     abled on the system).

		     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 architec-
		     tures 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	write-
		     able. 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.

		     All  directory  updates  within the file system should be
		     done synchronously.  This affects	the  following	system
		     calls:  creat, link, unlink, symlink, mkdir, rmdir, mknod
		     and rename.

	      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 op-
		     tion line users,exec,dev,suid).

       --bind Remount a	subtree	somewhere  else	 (so  that  its	 contents  are
	      available	in both	places). See above.

       --move Move a subtree to	some other place. See above.

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

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

Mount options for affs
       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 orig-
	      inal  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 sys-

       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  de-

	      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	utili-
	      ties may react to	such strings in	/etc/fstab.)

Mount options for coherent

Mount options for devpts
       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
       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
       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	behav-
	      iour  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  bit-
	      maps  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 meaning-

       debug  Print debugging info upon	each (re)mount.

       errors=continue / errors=remount-ro / errors=panic
	      Define the behaviour when	an error is encountered.  (Either  ig-
	      nore  errors  and	 just  mark the	file system erroneous and con-
	      tinue, 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	avail-
	      able 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  su-
	      perblocks, 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
       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.	Other-
	      wise,  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  al-
	      ways 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 commit-
		     ted to the	journal.  This is rumoured to be the  highest-
		     throughput	 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
       (Note:  fat  is not a separate filesystem, but a	common part of the ms-
       dos, 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.

	      Set  the	umask applied to directories only.  The	default	is the
	      umask of the current process.  The  value	 is  given  in	octal.
	      Present since 2.5.43.

	      Set the umask applied to regular files only.  The	default	is the
	      umask of the current process.  The  value	 is  given  in	octal.
	      Present since 2.5.43.

	      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  be-
		     comes, leading and embedded	spaces are ac-
		     cepted 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  con-
	      version.	 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 mod-
	      ule loading.

	      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 file-
	      names 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
       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 fol-
	      lowed by NL) when	reading	a file.	 For conv=auto,	choose more or
	      less  at random between conv=binary and conv=text.  For conv=bi-
	      nary, just read what is in the file. This	is the default.

	      Do not abort mounting when certain consistency checks fail.

Mount options for iso9660
       ISO 9660	is a standard describing a filesystem structure	to be used  on
       CD-ROMs.	 (This filesystem type is also seen on some DVDs. See also the
       udf filesystem.)

       Normal iso9660 filenames	appear in a 8.3	 format	 (i.e.,	 DOS-like  re-
       strictions  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	avail-
	      able. 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  to-
	      gether 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  dan-
	      gerous, 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

Mount options for msdos
       See mount options for fat.  If the msdos	file system detects an	incon-
       sistency,  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
       Just like nfs, the ncp implementation  expects  a  binary  argument  (a
       struct  ncp_mount_data) to the mount system call. This argument is con-
       structed	by ncpmount(8) and the current version of  mount  (2.6h)  does
       not know	anything about ncp.

Mount options for nfs
       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 faster	than with the  default
	      buffer  size of 4096. (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
	      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  un-
	      known  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 en-

	      If enabled (posix=1), the	file system distinguishes between  up-
	      per  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.  The umask  value  is
	      given in octal.  By default, the files are owned by root and not
	      readable by somebody else.

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

Mount options for ramfs
       Ramfs  is  a memory based filesystem. Mount it and you have it. Unmount
       it and it is gone. Present since	Linux 2.3.99pre4.  There are no	 mount

Mount options for reiserfs
       Reiserfs	 is  a	journaling filesystem.	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 pre-
		     serves  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 de-
		     fault 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 sys-

	      Tunes the	block allocator. This may provide performance improve-
	      ments in some situations.

	      Tunes the	block allocator. This may provide performance improve-
	      ments in some situations.

	      Disable  the border allocator algorithm invented by Yury Yu. Ru-
	      pasov.  This may provide performance improvements	in some	situa-

       nolog  Disable  journalling.  This  will	provide	slight performance im-
	      provements 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 ac-
	      tual  writes into	its journalling	area.  Implementation of nolog
	      is a work	in progress.

       notail By default, reiserfs stores small	files  and  `file  tails'  di-
	      rectly  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 ac-
	      tually mount the file system. Mainly used	by reiserfsck.

	      A	remount	option which permits online expansion of reiserfs par-
	      titions.	 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

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

Mount options for sysv

Mount options for tmpfs
       The following parameters	accept a suffix	k, m or	g for Ki, Mi, Gi  (bi-
       nary 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
       udf  is	the  "Universal	Disk Format" filesystem	defined	by the Optical
       Storage Technology Association, and is often  used  for	DVD-ROM.   See
       also iso9660.

       gid=   Set the default group.

       umask= Set the default umask.  The value	is given in octal.

       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
	      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.
		     (Don't forget to give the -r option.)

	      44bsd  For  filesystems  created	by  a  BSD-like	 system	 (Net-

	      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
		     only).   The  same	filesystem type	is also	used by	Mac OS

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

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

	      Translate	 unhandled  Unicode  characters	to special escaped se-
	      quences.	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  charac-
	      ter, 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.


	      Defines the behaviour for	 creation  and	display	 of  filenames
	      which fit	into 8.3 characters. If	a long name for	a file exists,
	      it will always be	preferred display. There are four modes:

	      lower  Force the short name to lower case	upon display; store  a
		     long name when the	short name is not all upper case.

	      win95  Force  the	short name to upper case upon display; store a
		     long name when the	short name is not all upper case.

	      winnt  Display the shortname as is; store	a long name  when  the
		     short name	is not all lower case or all upper case.

	      mixed  Display  the short	name as	is; store a long name when the
		     short name	is not all upper case.

       The default is "lower".

Mount options for xenix

Mount options for xfs
	      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,  in-
	      clusive  (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 ba-
	      sis 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 filesys-
	      tems 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 mem-
	      ory 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  op-
	      tional,  and  the	log section can	be separate from the data sec-
	      tion 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 in-
	      consistent when mounted in norecovery mode.  Some	files  or  di-
	      rectories	 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) en-

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

       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 re-
	      store 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	speci-
	      fied, and	must be	a multiple of the sunit	value.

Mount options for xiafs
       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.

       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 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 al-
       located by mount	will be	freed by umount.  You can also free a loop de-
       vice by hand, using `losetup -d', see losetup(8).

       mount has the following return codes (the bits can be ORed):

       0      success

       1      incorrect	invocation or permissions

       2      system error (out	of memory, cannot fork,	no more	loop devices)

       4      internal mount bug or missing nfs	support	in mount

       8      user interrupt

       16     problems writing or locking /etc/mtab

       32     mount failure

       64     some mount succeeded

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

       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),

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

       Some Linux file systems don't support -o	sync and -o dirsync (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 ex-
       ample, but you can't change gid or umask	for the	fatfs).

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

Linux 2.0		       14 September 1997		      MOUNT(8)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | FILESYSTEM SPECIFIC MOUNT OPTIONS | Mount options for adfs | Mount options for affs | Mount options for coherent | Mount options for devpts | Mount options for ext | Mount options for ext2 | Mount options for ext3 | Mount options for fat | Mount options for hpfs | Mount options for iso9660 | Mount options for minix | Mount options for msdos | Mount options for ncp | Mount options for nfs | Mount options for ntfs | Mount options for proc | Mount options for ramfs | Mount options for reiserfs | Mount options for romfs | Mount options for smbfs | Mount options for sysv | Mount options for tmpfs | Mount options for udf | Mount options for ufs | Mount options for umsdos | Mount options for vfat | Mount options for xenix | Mount options for xfs | Mount options for xiafs | THE LOOP DEVICE | RETURN CODES | FILES | SEE ALSO | BUGS | HISTORY

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