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

       mount - mount a file system

       mount [-lhV]

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

       All files accessible in a Unix system are arranged in one big tree, the
       file hierarchy, rooted at /.  These files can be spread out  over  sev-
       eral  devices. The mount command serves to attach the file system found
       on some device to the big file tree. Conversely, the umount(8)  command
       will detach it again.

       The standard form of the mount command, is
              mount -t type device dir
       This  tells the kernel to attach the file system found on device (which
       is of type type) at the directory dir.  The previous contents (if  any)
       and  owner  and  mode of dir become invisible, and as long as this file
       system remains mounted, the pathname dir refers to the root of the file
       system on device.

       Three forms of invocation do not actually mount anything:
              mount -h
       prints a help message;
              mount -V
       prints a version string; and just
              mount [-l] [-t type]
       lists  all mounted file systems (of type type).  The option -l adds the
       (ext2, ext3 and XFS) labels in this listing.  See below.

       Since Linux 2.4.0 it is possible to remount part of the file  hierarchy
       somewhere else. The call is
              mount --bind olddir newdir
       After this call the same contents is accessible in two places.  One can
       also remount a single file (on a single file).

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

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

       Since Linux 2.5.1 it is possible to atomically move a mounted  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.  (The customary choice none is less fortunate:
       the error message `none busy' from umount can be confusing.)

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

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

       (i) The command
              mount -a [-t type] [-O optlist]
       (usually given in a bootscript) causes all file  systems  mentioned  in
       fstab  (of  the  proper  type  and/or  having  or not having the proper
       options) to be mounted as indicated, except for those whose  line  con-
       tains the noauto keyword. Adding the -F option will make mount fork, so
       that the filesystems are mounted simultaneously.

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

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

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

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

       When the proc filesystem is mounted (say at /proc), the files /etc/mtab
       and /proc/mounts have very similar contents. The  former  has  somewhat
       more  information, such as the mount options used, but is not necessar-
       ily up-to-date (cf. the -n option below). It  is  possible  to  replace
       /etc/mtab  by  a symbolic link to /proc/mounts, and especially when you
       have very large numbers of mounts things will be much faster with  that
       symlink, but some information is lost that way, and in particular work-
       ing with the loop device will be less convenient, and using the  "user"
       option will fail.

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

       Options available for the mount command:

       -V     Output version.

       -h     Print a help message.

       -v     Verbose mode.

       -p num If the mount requires a passphrase to be entered, read  it  from
              file descriptor num instead of from the terminal.

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

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

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

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

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

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

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

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

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

       -w     Mount the file system read/write. This is the default. A 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 sys-
              tem type.  The file system types which are  currently  supported
              include:  adfs,  affs,  autofs,  coda, coherent, cramfs, devpts,
              efs, ext, ext2, ext3, hfs, hpfs,  iso9660,  jfs,  minix,  msdos,
              ncpfs,  nfs,  ntfs,  proc,  qnx4, ramfs, reiserfs, romfs, smbfs,
              sysv, tmpfs, udf, ufs, umsdos, usbfs, vfat, xenix,  xfs,  xiafs.
              Note that coherent, sysv and xenix are equivalent and that xenix
              and coherent will be removed at some point in the future --  use
              sysv  instead.  Since  kernel  version  2.1.21 the types ext and
              xiafs do not exist anymore. Earlier, usbfs was known  as  usbde-

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

              If no -t option is given, or if  the  auto  type  is  specified,
              mount will try to guess the desired type.  If mount was compiled
              with the blkid library, the guessing is done  by  this  library.
              Otherwise,  mount  guesses  itself by probing the superblock; if
              that does not turn up anything that looks familiar,  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

              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 ext3 before ext2) or  if  you
              use  a  kernel  module  autoloader.  Warning: the probing uses a
              heuristic (the presence of appropriate `magic'), and could  rec-
              ognize  the  wrong  filesystem  type, possibly with catastrophic
              consequences. If your data  is  valuable,  don't  ask  mount  to

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

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

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

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

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

       -o     Options  are  specified with a -o flag followed by a comma sepa-
              rated string of options.  Some of these options are only  useful
              when  they appear in the /etc/fstab file.  The following options
              apply to any file system that is being mounted  (but  not  every
              file  system  actually honors them - e.g., the sync option today
              has effect only for ext2, ext3 and ufs):

              async  All I/O to the file system should be done asynchronously.

              atime  Update inode access time for each  access.  This  is  the

              auto   Can be mounted with the -a option.

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

              dev    Interpret character or block special devices on the  file

              exec   Permit execution of binaries.

              group  Allow an ordinary (i.e., non-root) user to mount the file
                     system if one of his groups  matches  the  group  of  the
                     device.  This option implies the options nosuid and nodev
                     (unless overridden  by  subsequent  options,  as  in  the
                     option line group,dev,suid).

              mand   Allow mandatory locks on this filesystem. See fcntl(2).

                     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).

                     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 direct execution  of  any  binaries  on  the
                     mounted  file system.  (Until recently it was possible to
                     run binaries anyway  using  a  command  like  /lib/ld*.so
                     /mnt/binary.  This  trick  fails  since  Linux  2.4.25  /

              nomand Do not allow mandatory locks on this filesystem.

              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.

              owner  Allow an ordinary (i.e., non-root) user to mount the file
                     system if he is the owner of  the  device.   This  option
                     implies  the  options nosuid and nodev (unless overridden
                     by  subsequent   options,   as   in   the   option   line

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

              ro     Mount the file system read-only.

              rw     Mount the file system read-write.

              suid   Allow set-user-identifier or set-group-identifier bits to
                     take effect.

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

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

              user   Allow an ordinary user to mount  the  file  system.   The
                     name  of  the mounting user is written to mtab so that he
                     can unmount the file system again.  This  option  implies
                     the  options noexec, nosuid, and nodev (unless overridden
                     by  subsequent   options,   as   in   the   option   line

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

                     Specifies an encryption algorithm to use.  Used  in  con-
                     junction with the loop option.

                     Specifies  the  key  size  to use for an encryption algo-
                     rithm. Used in conjunction with the loop  and  encryption

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

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

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

       What  options  are supported depends a bit on the running kernel.  More
       info  may  be  found  in  the  kernel  source  subdirectory  Documenta-

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

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

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

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

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

              Do not allow any changes to the protection bits on the file sys-

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

              Print an informational message for each successful mount.

              Prefix used before volume name, when following a link.

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

              (Default:  2.)  Number  of  unused  blocks  at  the start of the

              Give explicitly the location of the root block.

              Give blocksize. Allowed values are 512, 1024, 2048, 4096.

       grpquota / noquota / quota / usrquota
              These options are accepted but ignored.  (However, quota  utili-
              ties may react to such strings in /etc/fstab.)

Mount options for coherent

Mount options for devpts
       The  devpts  file system is a pseudo file system, traditionally mounted
       on /dev/pts.  In order to acquire a pseudo terminal,  a  process  opens
       /dev/ptmx;  the number of the pseudo terminal is then made available to
       the  process  and  the  pseudo  terminal  slave  can  be  accessed   as

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

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

Mount options for ext
       None.   Note  that  the  `ext'  file  system is obsolete. Don't use it.
       Since Linux version 2.1.21 extfs  is  no  longer  part  of  the  kernel

Mount options for ext2
       The  `ext2' file system is the standard Linux file system.  Since Linux
       2.5.46, for most  mount  options  the  default  is  determined  by  the
       filesystem superblock. Set them with tune2fs(8).

       acl / noacl
              Support POSIX Access Control Lists (or not).

       bsddf / minixdf
              Set the behaviour for the statfs system call. The minixdf behav-
              iour is to return in the f_blocks  field  the  total  number  of
              blocks  of  the file system, while the bsddf behaviour (which is
              the default) is to subtract the overhead blocks used by the ext2
              file system and not available for file storage. Thus

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

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

       check  Check filesystem (block and inode bitmaps) at mount time.

       check=none / nocheck
              No checking is done at mount time. This is the default. This  is
              fast.   It  is wise to invoke e2fsck(8) every now and then, e.g.
              at boot time.

       debug  Print debugging info upon each (re)mount.

       errors=continue / errors=remount-ro / errors=panic
              Define the behaviour when  an  error  is  encountered.   (Either
              ignore  errors  and just mark the file system erroneous and con-
              tinue, or remount the file system read-only, or panic  and  halt
              the  system.)   The default is set in the filesystem superblock,
              and can be changed using tune2fs(8).

       grpid or bsdgroups / nogrpid or sysvgroups
              These options define what group id a newly  created  file  gets.
              When  grpid  is  set,  it takes the group id of the directory in
              which it is created; otherwise (the default) it takes the  fsgid
              of  the current process, unless the directory has the setgid bit
              set, in which case it takes the gid from the  parent  directory,
              and also gets the setgid bit set if it is a directory itself.

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

       nobh   Do not attach buffer_heads to file pagecache. (Since 2.5.49.)

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

       oldalloc or orlov
              Use old allocator or Orlov allocator for new  inodes.  Orlov  is

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

       sb=n   Instead  of  block  1,  use block n as superblock. This could be
              useful when the filesystem has been damaged.   (Earlier,  copies
              of  the  superblock would be made every 8192 blocks: in block 1,
              8193, 16385, ... (and one got  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".

       user_xattr / nouser_xattr
              Support "user." extended attributes (or not).

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

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

              When  a  journal  already exists, this option is ignored. Other-
              wise, it specifies the number of the inode which will  represent
              the  ext3  file  system's  journal file;  ext3 will create a new
              journal, overwriting the old contents of the  file  whose  inode
              number is inum.

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

       data=journal / data=ordered / data=writeback
              Specifies  the  journalling  mode  for  file  data.  Metadata is
              always journaled.  To use modes other than ordered on  the  root
              file system, pass the mode to the kernel as boot parameter, e.g.

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

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

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

              Sync all data and metadata  every  nrsec  seconds.  The  default
              value is 5 seconds. Zero means default.

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.)

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

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

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

              Three different levels of pickyness can be chosen:

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

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

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

              Sets the codepage for converting to shortname characters on  FAT
              and VFAT filesystems. By default, codepage 437 is used.

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

              binary no translation is performed.  This is the default.

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

              auto   CRLF<-->NL  translation  is  performed  on all files that
                     don't have a "well-known binary" extension. The  list  of
                     known  extensions  can  be  found  at  the  beginning  of
                     fs/fat/misc.c (as of 2.0, the list  is:  exe,  com,  bin,
                     app,  sys,  drv,  ovl, ovr, obj, lib, dll, pif, arc, zip,
                     lha, lzh, zoo, tar, z, arj, tz, taz, tzp, tpz,  gz,  tgz,
                     deb,  gif,  bmp, tif, gl, jpg, pcx, tfm, vf, gf, pk, pxl,

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

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

              Forces the driver to use the CVF (Compressed Volume File) module
              cvf_module instead of auto-detection.  If  the  kernel  supports
              kmod, the cvf_format=xxx option also controls on-demand CVF mod-
              ule loading.

              Option passed to the CVF module.

       debug  Turn on the debug flag.  A version string and  a  list  of  file
              system  parameters  will be printed (these data are also printed
              if the parameters appear to be inconsistent).

       fat=12 / fat=16 / fat=32
              Specify a 12, 16 or 32 bit fat.  This  overrides  the  automatic
              FAT type detection routine.  Use with caution!

              Character set to use for converting between 8 bit characters and
              16 bit Unicode characters. The default is iso8859-1.  Long file-
              names are stored on disk in Unicode format.

       quiet  Turn on the quiet flag.  Attempts to chown or chmod files do not
              return errors, although they fail. Use with caution!

       sys_immutable, showexec, dots, nodots, dotsOK=[yes|no]
              Various misguided attempts to force Unix or DOS conventions onto
              a FAT file system.

Mount options for hfs
       creator=cccc, type=cccc
              Set  the  creator/type  values as shown by the MacOS finder used
              for creating new files.  Default values: '????'.

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

       dir_umask=n, file_umask=n, umask=n
              Set  the  umask  used for all directories, all regular files, or
              all files and directories.  Defaults to the umask of the current

              Select  the  CDROM  session  to mount.  Defaults to leaving that
              decision to the CDROM driver.  This option will fail  with  any-
              thing but a CDROM as underlying device.

       part=n Select partition number n from the device.  Only makes sense for
              CDROMS.  Defaults to not parsing the partition table at all.

       quiet  Don't complain about invalid mount options.

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

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

       case=lower / case=asis
              Convert all files names to lower case, or leave them.  (Default:

       conv=binary / conv=text / conv=auto
              For conv=text, delete some random CRs (in particular,  all  fol-
              lowed by NL) when reading a file.  For conv=auto, choose more or
              less  at  random  between  conv=binary   and   conv=text.    For
              conv=binary, just read what is in the file. This is the default.

              Do not abort mounting when certain consistency checks fail.

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

       Normal  iso9660  filenames  appear  in  a  8.3  format  (i.e., DOS-like
       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.

              Disable  the  use of Microsoft Joliet extensions, even if avail-
              able. Cf. map.

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

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

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

              For non-Rock Ridge volumes, give all files the  indicated  mode.
              (Default:  read  permission  for everybody.)  Since Linux 2.1.37
              one no longer needs to specify the mode in  decimal.  (Octal  is
              indicated by a leading 0.)

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

              Set   the   block   size  to  the  indicated  value.   (Default:

       conv=a[uto] / conv=b[inary] / conv=m[text] / conv=t[ext]
              (Default: conv=binary.)  Since Linux 1.3.54 this option  has  no
              effect  anymore.   (And non-binary settings used to be very dan-
              gerous, possibly leading to silent data corruption.)

       cruft  If the high byte of the file length contains other garbage,  set
              this  mount  option  to  ignore  the high order bits of the file
              length.  This implies that a file cannot be larger than 16MB.

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

              Session begins from sector xxx. (Since 2.3.4.)

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

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

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

Mount options for jfs
              Character  set to use for converting from Unicode to ASCII.  The
              default is to do no conversion.   Use  iocharset=utf8  for  UTF8
              translations.   This  requires  CONFIG_NLS_UTF8 to be set in the
              kernel .config file.

              Resize the volume to value blocks. JFS only supports  growing  a
              volume,  not  shrinking  it.  This option is only valid during a
              remount, when the volume is mounted read-write. The resize  key-
              word  with no value will grow the volume to the full size of the

              Do not write to the journal.  The primary use of this option  is
              to  allow  for  higher  performance when restoring a volume from
              backup media. The integrity of the volume is not  guaranteed  if
              the system abnormally abends.

              Default.   Commit  metadata  changes  to  the journal.  Use this
              option to remount a volume where the nointegrity option was pre-
              viously specified in order to restore normal behavior.

       errors=continue / errors=remount-ro / errors=panic
              Define  the  behaviour  when  an  error is encountered.  (Either
              ignore errors and just mark the file system erroneous  and  con-
              tinue,  or  remount the file system read-only, or panic and halt
              the system.)

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

Mount options for minix

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

Mount options for ncpfs
       Just like nfs, the ncpfs implementation expects a  binary  argument  (a
       struct  ncp_mount_data) to the mount system call. This argument is con-
       structed by ncpmount(8) and the current version of  mount  (2.12)  does
       not know anything about ncpfs.

Mount options for nfs
       Instead  of a textual option string, parsed by the kernel, the nfs file
       system expects a binary argument of type  struct  nfs_mount_data.   The
       program   mount  itself  parses  the  following  options  of  the  form
       `tag=value',  and  puts  them  in  the  structure  mentioned:  rsize=n,
       wsize=n,   timeo=n,   retrans=n,  acregmin=n,  acregmax=n,  acdirmin=n,
       acdirmax=n, actimeo=n, retry=n,  port=n,  mountport=n,  mounthost=name,
       mountprog=n,  mountvers=n,  nfsprog=n, nfsvers=n, namlen=n.  The option
       addr=n is accepted but ignored.  Also the  following  Boolean  options,
       possibly  preceded  by  no  are  recognized:  bg, fg, soft, hard, intr,
       posix, cto, ac, tcp, udp, lock.  For details, see nfs(5).

       Especially useful options include

              This will make your nfs connection faster than with the  default
              buffer  size of 4096. (NFSv2 does not work with larger values of
              rsize and wsize.)

       hard   The program accessing a file on a NFS mounted file  system  will
              hang  when the server crashes. The process cannot be interrupted
              or killed unless you also specify intr.  When the NFS server  is
              back  online the program will continue undisturbed from where it
              was. This is probably what you want.

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

       nolock Do not use locking. Do not start lockd.

Mount options for ntfs
              Character  set  to  use when returning file names.  Unlike VFAT,
              NTFS suppresses names  that  contain  unconvertible  characters.

              New name for the option earlier called iocharset.

       utf8   Use UTF-8 for converting file names.

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

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

       uid=value, gid=value and umask=value
              Set  the  file permission on the filesystem.  The umask value is
              given in octal.  By default, the files are owned by root and not
              readable by somebody else.

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

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

Mount options for reiserfs
       Reiserfs is a journaling filesystem.  The reiserfs  mount  options  are
       more fully described at 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

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

                     A hash invented by Yury Yu. Rupasov.  It is fast and pre-
                     serves locality,  mapping  lexicographically  close  file
                     names  to  close  hash values.  This option should not be
                     used, as it causes a high probability of hash collisions.

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

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

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

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

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

              Disable the border allocator  algorithm  invented  by  Yury  Yu.
              Rupasov.  This may provide performance improvements in some sit-

       nolog  Disable  journalling.  This  will  provide  slight   performance
              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.   Implementation  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.

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

              A remount option which permits online expansion of reiserfs par-
              titions.  Instructs reiserfs to assume that the device has  num-
              ber  blocks.  This option is designed for use with devices which
              are under logical volume management (LVM).  There is  a  special
              resizer     utility     which     can     be    obtained    from

Mount options for romfs

Mount options for smbfs
       Just like nfs, the smbfs implementation expects a  binary  argument  (a
       struct  smb_mount_data) to the mount system call. This argument is con-
       structed by smbmount(8) and the current version of  mount  (2.12)  does
       not know anything about smbfs.

Mount options for sysv

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.

              Override default maximum size of the filesystem.   The  size  is
              given  in  bytes, and rounded down to entire pages.  The default
              is half of the memory.

              Set number of blocks.

              Set number of inodes.

       mode=  Set initial permissions of the root directory.

Mount options for udf
       udf is the "Universal Disk Format" filesystem defined  by  the  Optical
       Storage  Technology  Association,  and  is often used for DVD-ROM.  See
       also iso9660.

       gid=   Set the default group.

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

       uid=   Set the default user.

       unhide Show otherwise hidden files.

              Show deleted files in lists.

              Unset strict conformance.

              Set the NLS character set.

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

       novrs  Skip volume sequence recognition.

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

              Override standard anchor location. Default: 256.

              Override the VolumeDesc location. (unused)

              Override the PartitionDesc location. (unused)

              Set the last block of the filesystem.

              Override the fileset block location. (unused)

              Override the root directory location. (unused)

Mount options for ufs
              UFS is a file system widely used in different operating systems.
              The  problem  are differences among implementations. Features of
              some implementations are undocumented, so its hard to  recognize
              the type of ufs automatically.  That's why the user must specify
              the type of ufs by mount option.  Possible values are:

              old    Old format of  ufs,  this  is  the  default,  read  only.
                     (Don't forget to give the -r option.)

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

              sun    For filesystems created by SunOS or Solaris on Sparc.

              sunx86 For filesystems created by Solaris on x86.

              hp     For filesystems created by HP-UX, read-only.

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

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

                     For  filesystems  created  by  OpenStep  (currently  read
                     only).  The same filesystem type is also used by  Mac  OS

              Set behaviour on error:

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

                     These mount options don't do anything at present; when an
                     error is encountered only a console message is printed.

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

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

              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 charac-
              ter, is: ':', (u & 0x3f), ((u>>6) & 0x3f), (u>>12).

       posix  Allow two files with names that only differ in case.

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

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


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

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

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

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

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

       The default is "lower".

Mount options for usbfs
       devuid=uid and devgid=gid and devmode=mode
              Set  the  owner  and  group  and mode of the device files in the
              usbfs file system (default: uid=gid=0, mode=0644). The  mode  is
              given in octal.

       busuid=uid and busgid=gid and busmode=mode
              Set  the  owner and group and mode of the bus directories in the
              usbfs file system (default: uid=gid=0, mode=0555). The  mode  is
              given in octal.

       listuid=uid and listgid=gid and listmode=mode
              Set  the  owner and group and mode of the file devices (default:
              uid=gid=0, mode=0444). The mode is given in octal.

Mount options for xenix

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

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

              Set the number of in-memory log buffers.   Valid  numbers  range
              from 2-8 inclusive.  The default value is 8 buffers for filesys-
              tems with a blocksize of 64K, 4 buffers for filesystems  with  a
              blocksize  of 32K, 3 buffers for filesystems with a blocksize of
              16K, and 2 buffers for all other configurations.  Increasing the
              number  of buffers may increase performance on some workloads at
              the cost of the memory used for the additional log  buffers  and
              their associated control structures.

              Set  the  size  of  each  in-memory log buffer.  Valid sizes are
              16384 (16K) and 32768 (32K).  The  default  value  for  machines
              with  more than 32MB of memory is 32768, machines with less mem-
              ory use 16384 by default.

       logdev=device and rtdev=device
              Use an external log (metadata journal) and/or real-time  device.
              An  XFS  filesystem has up to three parts: a data section, a log
              section, and a real-time  section.   The  real-time  section  is
              optional, and the log section can be separate from the data sec-
              tion or contained within it.  Refer to xfs(5).

              Data allocations will not be aligned at stripe unit boundaries.

              Access timestamps are not updated when a file is read.

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

       nouuid Ignore  the  filesystem  uuid.  This avoids errors for duplicate

              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)

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

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

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

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

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

       will  set  up  the  loop  device  /dev/loop3  to correspond to the file
       /tmp/fdimage, and then mount this device on /mnt.

       This type of mount knows about three options, namely loop,  offset  and
       encryption,  that  are  really  options  to  losetup(8).   If the mount
       requires a passphrase, you will be prompted for one unless you  specify
       a  file  descriptor  to  read  from  instead with the --pass-fd option.
       (These options can be  used  in  addition  to  those  specific  to  the
       filesystem type.)

       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).

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

       0      success

       1      incorrect invocation or permissions

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

       4      internal mount bug or missing nfs support in mount

       8      user interrupt

       16     problems writing or locking /etc/mtab

       32     mount failure

       64     some mount succeeded

       /etc/fstab        file system table

       /etc/mtab         table of mounted file systems

       /etc/mtab~        lock file

       /etc/mtab.tmp     temporary file

       /etc/filesystems  a list of filesystem types to try

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

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

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

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

       Mount by label or uuid will work only if your devices  have  the  names
       listed  in  /proc/partitions.   In  particular, it may well fail if the
       kernel was compiled with devfs but devfs is not mounted.

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

Linux 2.6                         2004-12-16                          MOUNT(8)