MOUNT linux command manual

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



NAME
       mount - mount a file system

SYNOPSIS
       mount [-lhV]

       mount -a [-fFnrsvw] [-t vfstype] [-O optlist]
       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
       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

       Note the filesystem mount options will remain the same as those on the
       original mount point, and cannot be changed by passing the  -o  option
       along with --bind/--rbind.

       Since  Linux  2.5.1  it  is  possible  to atomically move a subtree to
       another 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 knuth.cwi.nl:/dir.  It is
       possible to indicate a block special device using its volume label  or
       UUID (see the -L and -U options below).

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

       (i) The command
              mount -a [-t type] [-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
       options)  to be mounted as indicated, except for those whose line con-
       tains 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 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 sim-
       ilar to the user option, with the restriction that the  user  must  be
       the  owner of the special file. This may be useful e.g. for /dev/fd if
       a login script makes the console user owner of this device.

       The programs mount and umount maintain a  list  of  currently  mounted
       file  systems  in  the  file  /etc/mtab.  If no arguments are given to
       mount, this list is printed.

       When the  proc  filesystem  is  mounted  (say  at  /proc),  the  files
       /etc/mtab  and /proc/mounts have very similar contents. The former has
       somewhat more information, such as the mount options used, but is  not
       necessarily  up-to-date  (cf.  the -n option below). It is possible to
       replace /etc/mtab by a symbolic link to /proc/mounts, but some  infor-
       mation  is  lost  that  way,  and  in particular working with the loop
       device will be less convenient, and using the "user" option will fail.


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 ta-
       ble,  then  applying  any  options  specified  by the -o argument, and
       finally applying a -r or -w option, when present.

       Options available for the mount command:

       -V     Output version.

       -h     Print a help message.

       -v     Verbose mode.

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

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

       -f     Causes everything to be done except for the actual system call;
              if it's not obvious, this ''fakes'' mounting the  file  system.
              This option is useful in conjunction with the -v flag to 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 option.

       -i     Don't call  the  /sbin/mount.  helper  even  if  it
              exists.

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

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

       -p num In case of a loop mount with encryption,  read  the  passphrase
              from file descriptor num instead of from the terminal.

       -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  syn-
              onym is -o rw.

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

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

       -t vfstype
              The argument following the -t is used to indicate the file 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,  nfs4,  ntfs,  proc,  qnx4, ramfs, reiserfs, romfs, smbfs,
              sysv, tmpfs, udf, ufs, umsdos, vfat, xenix, xfs,  xiafs.   Note
              that coherent, sysv and xenix are equivalent and that xenix and
              coherent will be removed at some point in the future -- use sysv
              instead. Since kernel version 2.1.21 the types ext and xiafs do
              not exist anymore.

              For most types all the mount program has to do is issue a  sim-
              ple  mount(2)  system  call,  and  no detailed knowledge of the
              filesystem type is required.  For a  few  types  however  (like
              nfs,  nfs4,  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.smbfs  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, nfs, and nfs4).  If  /etc/filesys-
              tems  ends  in  a  line  with  a single * only, mount will read
              /proc/filesystems afterwards.

              The auto type may be useful for user-mounted floppies.   Creat-
              ing  a  file /etc/filesystems can be useful to change the probe
              order (e.g., to try vfat before msdos) or if you use  a  kernel
              module  autoloader.  Warning: the probing uses a heuristic (the
              presence of appropriate 'magic'), and could recognize the wrong
              filesystem  type,  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 spec-
              ify 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-
              mand:
                     mount -a -O no_netdev
              mounts all file systems except  those  which  have  the  option
              _netdev  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
              rest.

              The -t and -O options are cumulative in effect;  that  is,  the
              command
                     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
              specified.

       -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  asyn-
                     chronously.

              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.

              _netdev
                     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
                     enabled on the system).

              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 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.

              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 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.

              dirsync
                     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
                     user,exec,dev,suid).

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

       --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.


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'  permissions  and
              'other'  permissions,  respectively  (default:  0700  and 0077,
              respectively).  See also  /usr/src/linux/Documentation/filesys-
              tems/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  speci-
              fied  value, the uid and gid of the current process are taken).

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

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

       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 utili-
              ties 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, 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
       /dev/pts/.

       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.

       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 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
       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 system, while the bsddf behaviour  (which
              is  the default) is to subtract the overhead blocks used by the
              ext2 file system and not available for file storage. Thus

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

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


       check / check=normal / check=strict
              Set  checking  level. When at least one of these options is set
              (and check=normal is set by  default)  the  inodes  and  blocks
              bitmaps are checked upon mount (which can take half a minute or
              so on a big disk, and is rather useless).  With  strict  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 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
              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 damaged.  (Earlier,  copies
              of  the superblock would be made every 8192 blocks: in block 1,
              8193, 16385, ... (and one got hundreds  or  even  thousands  of
              copies  on  a big filesystem). Since version 1.08, mke2fs has a
              -s (sparse superblock) option to reduce the  number  of  backup
              superblocks,  and  since version 1.15 this is the default. Note
              that this may mean that ext2 filesystems created  by  a  recent
              mke2fs  cannot  be  mounted  r/w under Linux 2.0.*.)  The block
              number here uses 1k units. Thus, if you  want  to  use  logical
              block 32768 on a filesystem with 4k blocks, use "sb=131072".

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


       nouid32
              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:

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

       journal=inum
              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
              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-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
       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.

       dmask=value
              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.

       fmask=value
              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.

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

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

              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 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,
                     dvi).

              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.

       cvf_format=module
              Forces  the driver to use the CVF (Compressed Volume File) mod-
              ule cvf_module instead of auto-detection. If  the  kernel  sup-
              ports  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.)

       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 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=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
       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
       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 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
              together with norock and map=normal.  (Default:  check=strict.)

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

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

       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.  (If the ordinary  files
              and  the  associated  or  hidden files have the same filenames,
              this may make the ordinary files inaccessible.)

       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 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.

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

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

       The following options are the same as for  vfat  and  specifying  them
       only  makes  sense  when  using discs encoded using Microsoft's Joliet
       extensions.

       iocharset=value
              Character set to use for converting 16 bit  Unicode  characters
              on CD to 8 bit characters. The default is iso8859-1.

       utf8   Convert 16 bit Unicode characters on CD to UTF-8.


Mount options for minix
       None.


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 ncpfs
       Just  like  nfs, the ncpfs 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 (2.12) does
       not know anything about ncpfs.


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

       rsize=8192,wsize=8192
              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  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 nfs4
       Instead of a textual option string, parsed by  the  kernel,  the  nfs4
       file  system expects a binary argument of type struct nfs4_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, proto=n, clientaddr=n, sec=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, cto, ac, For details, see nfs(5).

       Especially useful options include

       rsize=32768,wsize=32768
              This will make your NFS connection faster than with the default
              buffer size of 4096.

       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  timeout  value  is expressed in tenths of a
              second.  The soft 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.   Avoid  using  this
              option with proto=udp or with a short timeout.


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.

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

       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 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 see.


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
       options.


Mount options for reiserfs
       Reiserfs  is  a journaling filesystem.  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 lexicographically 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  collisions at come CPU cost.  This may be used
                     if EHASHCOLLISION errors are  experienced  with  the  r5
                     hash.

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

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

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

       no_unhashed_relocation
              Tunes  the  block  allocator.  This  may  provide   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  performance
              improvements in some situations at the  cost  of  losing  reis-
              erfs'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.  Implementa-
              tion 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.

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

       resize=number
              A remount option which permits  online  expansion  of  reiserfs
              partitions.   Instructs  reiserfs to assume that the device has
              number 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
              ftp://ftp.namesys.com/pub/reiserfsprogs.


Mount options for romfs
       None.


Mount options for smbfs
       Just  like  nfs, the smbfs 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 (2.12) does
       not know anything about smbfs.


Mount options for sysv
       None.


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

       size=nbytes
              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.

       nr_blocks=
              Set number of blocks.

       nr_inodes=
              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.

       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)

       rootdir=
              Override the root directory location. (unused)


Mount options for ufs
       ufstype=value
              UFS  is  a  file system widely used in different operating sys-
              tems.  The problem are differences among implementations.  Fea-
              tures  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
                     (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  (currently read
                     only).  The same filesystem type is also used by Mac  OS
                     X.


       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 explicitly killed
       by umsdos.


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

       shortname=[lower|win95|winnt|mixed]

              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
       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 pagesize, 13 (8K bytes) is also a valid size.  The preferred
              buffered  I/O  size  can  also be altered on an individual file
              basis using the ioctl(2) system call.

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

       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  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  addi-
              tional 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 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
              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
              directories 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.

       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 speci-
              fied for the RAID device at mkfs time, then  the  mount  system
              call  will restore the value from the superblock.  For filesys-
              tems 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 losetup(8).  If no explicit loop device is  men-
       tioned (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).


RETURN CODES
       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


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)

BUGS
       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
       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                      MOUNT(8)