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

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

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

       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 contains the  noauto  keyword.
       Adding  the  -F  option  will make mount fork, so that the
       filesystems are mounted simultaneously.

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

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

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

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


OPTIONS

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


       Options available for the mount command:

       -V     Output version.

       -h     Print a help message.

       -v     Verbose mode.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

              More than one type may  be  specified  in  a  comma

              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
              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.   That  is,
              while
                     mount -a -t nomsdos,ext
              mounts  filesystems  that are neither msdos nor ext
              (the no applies to both msdos and  ext2  filesystem
              types),
                     mount -a -O no_netdev,user
              mounts all filesystems that do not have the _netdev
              option and do have the user option.   In  order  to
              specify neither _netdev nor user options, use:
                     mount -a -O no_netdev,nouser

              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  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.


              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-
                     group-identifier  bits to take effect. (This
                     seems safe, but is in fact rather unsafe  if
                     you have suidperl(1) installed.)

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

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

              ro     Mount the file system read-only.

              rw     Mount the file system read-write.

                     tifier bits to take effect.

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

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


FILESYSTEM SPECIFIC MOUNT OPTIONS

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


Mount options for adfs

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

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


Mount options for affs

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

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

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

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

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

              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>.

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

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

       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
              read-only, or panic  and  halt  the  system.)   The
              default  is  set  in the filesystem superblock, and
              can be changed using tune2fs(8).

              These options define what group id a newly  created
              file  gets.   When grpid is set, it takes the group
              id of the directory in which it is created;  other­
              wise  (the  default) it takes the fsgid of the cur­
              rent process, unless the directory has  the  setgid
              bit  set,  in  which case it takes the gid from the
              parent directory, and also gets the setgid bit  set
              if it is a directory itself.

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

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

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

       nouid32
              Disables 32-bit UIDs and GIDs.  This is for  inter­
              operability with older kernels which only store and
              expect 16-bit values.


Mount options for ext3

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

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

       journal=inum
              When  a  journal  already  exists,  this  option is
              ignored. Otherwise, it specifies the number of  the
              inode  which  will represent the ext3 file system's

              overwriting  the  old  contents  of  the file whose
              inode number is inum.

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

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

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

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

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


Mount options for fat

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

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

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

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

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

              r[elaxed]
                     Upper and lower case are accepted and equiv­
                     alent,  long  name parts are truncated (e.g.

                     leading  and embedded spaces are accepted in
                     each name part (name and extension).

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

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

       codepage=value
              Sets the codepage for converting to shortname char­
              acters  on  FAT  and  VFAT filesystems. By default,
              codepage 437 is used.

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

              binary no  translation  is  performed.  This is the
                     default.

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

              auto   CRLF<-->NL  translation  is performed on all
                     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


       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 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.

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

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

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

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

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

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

       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.)

              (Default:  conv=binary.)   Since  Linux 1.3.54 this
              option has no effect anymore.  (And non-binary set­
              tings  used  to be very dangerous, possibly leading
              to silent data corruption.)

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

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

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


Mount options for minix

       None.


Mount options for msdos

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


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,


       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  pro­
              cess  cannot  be  interrupted  or killed unless you
              also specify intr.  When the  NFS  server  is  back
              online  the  program will continue undisturbed from
              where it was. This is probably what you want.

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

       nolock Do not use locking. Do not start lockd.


Mount options for ntfs

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

       utf8   Use UTF-8 for converting file names.

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

       posix=[0|1]
              If enabled (posix=1), the file system distinguishes
              between upper and lower case. The 8.3  alias  names
              are  presented  as hard links instead of being sup­
              pressed.

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

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


Mount options for reiserfs

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

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

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

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

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

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

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

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

       noborder
              Disable the border allocator algorithm invented  by
              Yury  Yu.  Rupasov  This  may  provide  performance


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

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

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

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

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


Mount options for romfs

       None.


Mount options for smbfs

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


Mount options for sysv

       None.


Mount options for udf

       gid=   Set the default group.

       umask= Set the default umask.

       uid=   Set the default user.


       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 oper­
              ating systems.  The problem are  differences  among
              implementations.  Features  of some implementations
              are undocumented, so its hard to recognize the type
              of  ufs  automatically.   That's  why the user must
              specify the type of ufs by mount option.   Possible
              values are:

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

              44bsd  For filesystems created by a BSD-like system
                     (NetBSD,FreeBSD,OpenBSD).

                     on Sparc.

              sunx86 For filesystems created by Solaris on x86.

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

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

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

       onerror=value
              Set behaviour on error:

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

              [lock|umount|repair]
                     These mount options  don't  do  anything  at
                     present; when an error is encountered only a
                     console message is printed.


Mount options for umsdos

       See mount options for msdos.  The dotsOK option is explic­
       itly killed by umsdos.


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.

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

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


Mount options for xenix

       None.


Mount options for xfs

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

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

       logbufs=value
              Set  the  number  of  in-memory log buffers.  Valid
              numbers range  from  2-8  inclusive.   The  default
              value is 8 buffers for filesystems with a blocksize
              of 64K, 4 buffers for filesystems with a  blocksize
              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,

              section or contained within it.  Refer to xfs(5).

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

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

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

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

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

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

       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.

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


THE LOOP DEVICE

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

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

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


FILES

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


SEE ALSO

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


BUGS

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

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

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


HISTORY

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


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