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


NAME
       mount - mount a file system

SYNOPSIS
       mount [-lhV]

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

DESCRIPTION
       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 spe-
       cial  device),  like /dev/sda1, but there are other possi-
       bilities. For example, in the case of an NFS mount, device
       may  look like knuth.cwi.nl:/dir.  It is possible to indi-
       cate a block special device using its volume label or UUID
       (see the -L and -U options below).




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       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 command
	      mount /dev/cdrom
       or
	      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  argu-
       ments  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
       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.



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       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) men-
	      tioned 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 unde-
	      fined 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  ear-
	      lier with the -n option.

       -l     Add the ext2, ext3 and XFS labels in the mount out-
	      put. 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 neces-
	      sary  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.





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       -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, minix, msdos, ncpfs, nfs,
	      ntfs,  proc,  qnx4,  reiserfs,  romfs, smbfs, sysv,
	      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 ker-
	      nel 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 possi-
	      ble 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
	      (minix, ext, ext2, ext3, xiafs,  iso9660,	 reiserfs
	      ,romfs,  ufs,  ntfs,  qnx4,  bfs,	 xfs, cramfs, hfs
	      ,hpfs, adfs 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  mod-
	      ule   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



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	      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 default.

	      auto   Can be mounted with the -a option.

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

	      dev    Interpret character or block special devices
		     on the file system.

	      exec   Permit execution of binaries.

	      noatime
		     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.




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	      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.

	      remount
		     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-iden-
		     tifier 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.  This  option  implies  the  options
		     noexec, nosuid, and nodev (unless overridden
		     by subsequent options, as in the option line
		     user,exec,dev,suid).


FILESYSTEM SPECIFIC MOUNT OPTIONS
       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 (default: uid=gid=0).

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

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).




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

       mode=value
	      Set  the	mode  of all files to value & 0777 disre-
	      garding the original permissions.	 Add search  per-
	      mission  to  directories that have read permission.
	      The value is given in octal.

       protect
	      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...

       verbose
	      Print an informational message for each  successful
	      mount.

       prefix=string
	      Prefix  used  before  volume name, when following a
	      link.

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

       reserved=value
	      (Default:	 2.) Number of unused blocks at the start
	      of the device.

       root=value
	      Give explicitly the location of the root block.

       bs=value
	      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
       None.


Mount options for devpts
       The devpts file system is a pseudo file system, tradition-
       ally mounted on /dev/pts.  In order to  acquire	a  pseudo



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       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
       /dev/pts/<number>.

       uid=value and gid=value
	      This sets the owner or the group of  newly  created
	      PTYs to the specified values. When nothing is spec-
	      ified, 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  cre-
	      ated PTYs to belong to the tty group.

       mode=value
	      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 cre-
	      ated 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 source.


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 2.0.4).

       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  sys-
	      tem,  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)



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	      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 check-
	      ing, block deallocation checks that  the	block  to
	      free is in the data zone.

       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;  other-
	      wise  (the  default) it takes the fsgid of the cur-
	      rent 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
	      group.)

       sb=n   Instead of block 1, use block n as superblock. This
	      could  be	 useful when the filesystem has been dam-
	      aged.  (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.*.)

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




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       nouid32
	      Disables 32-bit UIDs and GIDs.  This is for  inter-
	      operability 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:

       journal=update
	      Update the ext3 file system's journal to	the  cur-
	      rent format.

       journal=inum
	      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.

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

	      ordered
		     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.

	      writeback
		     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	 highest-through-
		     put  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



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       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.)

       umask=value
	      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.

       check=value
	      Three different levels of pickyness can be chosen:

	      r[elaxed]
		     Upper and lower case are accepted and equiv-
		     alent,  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).

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

	      s[trict]
		     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, etc.)

       codepage=value
	      Sets the codepage for converting to shortname char-
	      acters  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  avail-
	      able:

	      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



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		     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, dvi).

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

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

       cvf_format=module
	      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 loading.

       cvf_option=option
	      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!

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



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       umask=value
	      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: case=lower.)

       conv=binary / conv=text / conv=auto
	      For  conv=text, delete some random CRs (in particu-
	      lar, 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.

       nocheck
	      Do  not  abort  mounting	when  certain consistency
	      checks fail.


Mount options for iso9660
       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. map.

       nojoliet
	      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 informa-
	      tion found in the Rock Ridge extensions.	(Default:
	      uid=0,gid=0.)




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       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.

       mode=value
	      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.

       block=[512|1024|2048]
	      Set  the	block  size  to	 the   indicated   value.
	      (Default: block=1024.)

       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 set-
	      tings  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.

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

       sbsector=xxx
	      Session begins from sector xxx. (Since 2.3.4.)


Mount options for minix
       None.


Mount options for msdos
       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  write-
       able again by remounting it.




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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 constructed 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, moun-
       thost=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

       rsize=8192,wsize=8192
	      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  pro-
	      cess  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 pro-
	      cess  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
       iocharset=name
	      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.



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       uni_xlate=[0|1|2]
	      For 0 (or `no'  or  `false')  or	1  (or	`yes'  or
	      `true'): use the VFAT-style encoding for file names
	      outside the current character set.  A  value  of	2
	      will disable the encoding with ":".

       posix=[0|1]
	      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 sup-
	      pressed.

       uid=value, gid=value and umask=value
	      Set the file  permission	on  the	 filesystem.   By
	      default,	the files are owned by root and not read-
	      able 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 see.


Mount options for reiserfs
       The  reiserfs  mount  options  are more fully described at
       http://www.namesys.com/mount-options.html

       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 tools.

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

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

	      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  colli-
		     sions 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



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		     is used by default and is	the  best  choice
		     unles  the	 file system has huge directories
		     and unusual file-name patterns.

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

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

       noborder
	      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  per-
	      formance	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.	Implemen-
	      tation 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.

       no_unhashed_relocation
	      Tunes the block allocator. This may provide perfor-
	      mance improvements in some situations.

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

       resize=nblocks
	      A remount option which permits online expansion  of
	      reiserfs	partitions.  Instructs reiserfs to assume
	      that  the	 device	 has  blocks.	This  option   is
	      designed for use with devices which are under logi-
	      cal volume management.


Mount options for romfs
       None.





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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 constructed by smbmount(8) and  the
       current	version	 of  mount  (2.9w) does not know anything
       about smb.


Mount options for sysv
       None.


Mount options for udf
       gid=   Set the default group.

       umask= Set the default umask.

       uid=   Set the default user.

       unhide Show otherwise hidden files.

       undelete
	      Show deleted files in lists.

       strict Set strict conformance (unused).

       utf8   (unused).

       iocharset
	      (unused).

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

       novrs  Skip volume sequence recognition.

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

       anchor=
	      Override standard anchor location. Default: 256.

       volume=
	      Override the VolumeDesc location. (unused)

       partition=
	      Override the PartitionDesc location. (unused)

       lastblock=
	      Set the last block of the filesystem.

       fileset=
	      Override the fileset block location. (unused)




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       rootdir=
	      Override the root directory location. (unused)


Mount options for ufs
       ufstype=value
	      UFS is a file system widely used in different oper-
	      ating 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
		     (NetBSD,FreeBSD,OpenBSD).

	      sun    For  filesystems created by SunOS or Solaris
		     on Sparc.

	      sunx86 For filesystems created by Solaris on x86.

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

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

	      openstep
		     For filesystems created  by  OpenStep  (cur-
		     rently read only).


       onerror=value
	      Set behaviour on error:

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

	      [lock|umount|repair]
		     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 explic-
       itly killed by umsdos.




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

       uni_xlate
	      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.

       nonumtail
	      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 Uni-
	      code 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
       None.


Mount options for xfs
       biosize=size
	      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  page-
	      size, 13 (8K bytes) is also a valid size.	 The pre-
	      ferred 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  call-
	      outs.

       logbufs=value
	      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



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	      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 per-
	      formance on some workloads at the cost of the  mem-
	      ory  used	 for the additional log buffers and their
	      associated control structures.

       logbsize=value
	      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).

       noalign
	      Data allocations will not be aligned at stripe unit
	      boundaries.

       noatime
	      Access timestamps are not updated when  a	 file  is
	      read.

       norecovery
	      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 directo-
	      ries   may  not  be  accessible  because	of  this.
	      Filesystems  mounted  norecovery	must  be  mounted
	      read-only or the mount will fail.

       osyncisdsync
	      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) enforced.

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



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       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
       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
       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  los-
       etup(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 allocated by mount will
       be freed by umount.  You can also free a	 loop  device  by
       hand, using `losetup -d', see losetup(8).


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

SEE ALSO
       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), losetup(8)




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

Linux 2.0		14 September 1997		       23
