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mount



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

       Since Linux 2.5.1 it is possible to atomically move a sub­
       tree 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.
       (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 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 con­
       tents. 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, 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 table,  then  applying  any  options
       specified by the -o argument, and finally applying a -r or
              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.

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

       -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.

       -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
              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 (adfs,
              bfs, cramfs, ext, ext2, ext3, hfs,  hpfs,  iso9660,
              jfs,  minix, ntfs, qnx4, reiserfs, romfs, udf, ufs,
              vxfs, xfs, xiafs are  supported).   If  this  probe
              fails,   mount   will   try   to   read   the  file
              /etc/filesystems,  or,  if  that  does  not  exist,
              /proc/filesystems.   All  of  the  filesystem types
              listed there will be tried, except for  those  that
              are  labeled  "nodev" (e.g., devpts, proc and nfs).
              If /etc/filesystems ends in a line with a single  *
              only, mount will read /proc/filesystems afterwards.

              The auto type may be useful for user-mounted  flop­
              pies.  Creating a file /etc/filesystems can be use­
              ful 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 valu­
              able, don't ask mount to guess.

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

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

       -O     Used  in  conjunction  with -a, to limit the set of
              filesystems to which the -a is applied.  Like -t in
              this regard except that it is useless except in the
              context of -a.  For example, the command:
                     mount -a -O no_netdev
              mounts all file systems except those which have the

       -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.

              _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 architectures  other
                     than its own.

              nosuid Do  not  allow  set-user-identifier  or set-
              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.

              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  con­
              tents 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'  permis­
              sions   and   'other'   permissions,   respectively
              (default: 0700 and 0077, respectively).   See  also
              /usr/src/linux/Documentation/filesystems/adfs.txt.

              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
       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>.



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)
              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

       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.*.)
              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 inter­
              operability with older kernels which only store and
              expect 16-bit values.

       user_xattr
              Enable  Extended  User  Attributes. See the attr(5)
              manual page.

       acl    Enable POSIX Access Control Lists. See  the  acl(5)
              manual page.


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
                     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.

              user_xattr
                     Enable  Extended  User  Attributes.  See the
                     attr(5) manual page.

              acl    Enable POSIX Access Control Lists.  See  the
                     acl(5) manual page.


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.


              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
                     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

       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  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

       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

       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.)

       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.)

       The  following options are the same as for vfat and speci­
       fying them only makes sense when using discs encoded using

       iocharset=name
              Character set to use for converting from Unicode to
              ASCII.  Joliet filenames are stored in Unicode for­
              mat, but Unix for the most part doesn't know how to
              deal with Unicode.  There  is  also  an  option  of
              doing UTF8 translations with the utf8 option.

       utf8   Encode Unicode names in UTF8 format. Default is no.


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.


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,  acl.   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.)


       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.

       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  bigen­
              dian 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 sup­
              pressed.

       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  some­
              body 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

              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
                     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  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 perfor­
              mance improvements in some situations.

       no_unhashed_relocation
              Tunes the block allocator. This may provide perfor­
              mance 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.

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

              manual page.


Mount options for romfs

       None.


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 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.

       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 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.  (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.

                     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.


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.

       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 dis­
                     play;  store a long name when the short name
                     is not all upper case.

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



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
              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.

              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
              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).

       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 syn­
       chronous 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)
  
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