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

       mount - mount a file system

       mount [-hV]

       mount -a [-fFnrsvw] [-t vfstype]
       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 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 [-t type]
       lists all mounted file systems (of type type) - see below.

       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  It is possible to indi-
       cate 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]
       (usually  given  in  a bootscript) causes all file systems
       mentioned in fstab (of the proper type) to be  mounted  as
       indicated, except for those whose line contains the noauto
       keyword. Adding the -F option will  make  mount  fork,  so
       that the filesystems are mounted simultaneously.

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

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

       Thus, given a line
              /dev/cdrom  /cd  iso9660  ro,user,noauto,unhide
       any  user  can  mount the iso9660 file system found on his
       CDROM using the command
              mount /dev/cdrom
              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 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.

       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.

       -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.

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

       -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

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

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

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

       -t vfstype
              The  argument  following the -t is used to indicate
              the file system type.  The file system types  which
              are    currently    supported    are    listed   in
              linux/fs/filesystems.c: minix,  xiafs,  ext,  ext2,
              msdos,  umsdos,  vfat,  proc,  autofs, devpts, nfs,
              iso9660, smbfs, ncpfs, adfs, affs, coda, hfs, hpfs,
              ntfs,  qnx4,  romfs,  ufs,  sysv,  xenix, coherent.
              Note that the last three are  equivalent  and  that
              xenix and coherent will be removed at some point in
              the future -- use sysv instead. Since  kernel  ver-
              sion  2.1.21  the  types ext and xiafs do not exist

              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 smb or ncp.  Since
              various versions of the smbmount program have  dif-
              ferent  calling  conventions,  /sbin/mount.smb  may
              have to be a shell script that sets up the  desired

              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, xiafs, iso9660, romfs  are  sup-
              ported).   If  this  probe fails, mount will try to
              read the file /etc/filesystems, or,  if  that  does
              not  exist, /proc/filesystems.  All of the filesys-
              tem types listed there will be  tried,  except  for
              those  that  are  labeled  "nodev"  (e.g., proc and

              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 sep-
              arated  list.  The list of file system types can be
              prefixed with no to specify the file  system  types
              on  which  no action should be taken.  (This can be
              meaningful with the -a option.)

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

       -o     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:

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

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

              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 system.

              exec   Permit execution of binaries.

                     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

              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.

                     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.

              ro     Mount the file system read-only.

              rw     Mount the file system read-write.

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

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

              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

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

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 disre-
              garding the original permissions.  Add search  per-
              mission  to  directories that have read permission.
              The value is given in octal.

              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.

              Print an informational message for each  successful

              Prefix  used  before  volume name, when following a

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

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

              Give explicitly the location of the root block.

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

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

Mount options for coherent

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

Mount options for ext2
       The  `ext2' file system is the standard Linux file system.
       Due to a kernel bug, it may be mounted with  random  mount
       options (fixed in Linux 2.0.4).

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

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

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

       check / check=normal / check=strict
              Set checking level. When  at  least  one  of  these
              options is set (and check=normal is set by default)
              the inodes and  blocks  bitmaps  are  checked  upon
              mount  (which can take half a minute or so on a big
              disk).  With strict  checking,  block  deallocation
              checks  that the block to free is in the data zone.

       check=none / nocheck
              No checking is done.

       debug  Print debugging info upon each (re)mount.

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

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

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

       sb=n   Instead of block 1, use block n as superblock. This
              could be useful when the filesystem has  been  dam-
              aged.   Usually, copies of the superblock are found
              every 8192 blocks: in block  1,  8193,  16385,  ...
              (Thus,  one  gets  hundreds  or  even  thousands of
              copies of the superblock on a big filesystem. I  do
              not  know  of  options  to  mke2fs that would cause
              fewer copies to be written.)

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

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
              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.

              Three different levels of pickyness can be chosen:

                     Upper and lower case are accepted and equiv-
                     alent,  long  name parts are truncated (e.g.
                     verylongname.foobar  becomes,
                     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, etc.)

       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-

              binary no  translation  is  performed.  This is the

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

              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.

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

       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.)

              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.

              Do not  abort  mounting  when  certain  consistency
              checks fail.

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

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

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

       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:

       map=n[ormal] / map=o[ff]
              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:

              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.

              Set   the   block  size  to  the  indicated  value.
              (Default: block=1024.)

       conv=a[uto] / conv=b[inary] / conv=m[text] / conv=t[ext]
              (Default: conv=binary.)  Since  Linux  1.3.54  this
              option has no effect anymore.  (And non-binary set-
              tings used to be very dangerous, often  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.

Mount options for minix

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

Mount options for ncp
       Just  like  nfs,  the  ncp implementation expects a binary
       argument (a struct ncp_mount_data)  to  the  mount  system
       call.  This argument is constructed by ncpmount(8) and the
       current version of mount (2.6h)  does  not  know  anything
       about ncp.

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

       Especially useful options include

              This will make your nfs connection much faster than
              with the default buffer size of 1024.

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

Mount options for romfs

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  (2.6c) does not know anything
       about smb.

Mount options for sysv

Mount options for ufs

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

              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

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

Mount options for xenix

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  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.

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

       mount(2),   umount(2),   fstab(5),  umount(8),  swapon(8),
       nfs(5), mountd(8), nfsd(8),  mke2fs(8),  tune2fs(8),  los-

       It  is  possible  for  a  corrupted file system to cause a

       Some Linux file systems don't support -o sync (the  ext2fs
       does  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).

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

Linux 2.0               14 September 1997                       1