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NAME

       mount - mount a file system

SYNOPSIS

       mount [-lhV]

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

DESCRIPTION

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

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

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

       Since Linux 2.4.0 it is possible to remount part of the file  hierarchy
       somewhere else. The call is
              mount --bind olddir newdir
       After this call the same contents is accessible in two places.  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

       Since  Linux 2.6.15 it is possible to mark a mount and its submounts as
       shared, private, slave or unbindable. A shared mount  provides  ability
       to create mirrors of that mount such that mounts and umounts within any
       of the mirrors propagate to the other mirror. A  slave  mount  receives
       propagation  from  its master, but any not vice-versa.  A private mount
       carries no propagation abilities.  A  unbindable  mount  is  a  private
       mount  which cannot cloned through a bind operation. Detailed semantics
       is documented in Documentation/sharedsubtree.txt  file  in  the  kernel
       source tree.
              mount --make-shared mountpoint
              mount --make-slave mountpoint
              mount --make-private mountpoint
              mount --make-unbindable mountpoint

       The following commands allows one to recursively change the type of all
       the mounts under a given mountpoint.
              mount --make-rshared mountpoint
              mount --make-rslave mountpoint
              mount --make-rprivate mountpoint
              "mount --make-runbindable mountpoint"

       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
       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, 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 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
       necessarily  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  working  with  the loop device will be less convenient, and
       using the "user" option will fail.

OPTIONS

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

       Options available for the mount command:

       -V     Output version.

       -h     Print a help message.

       -v     Verbose mode.

       -p passwdfd
              If  the  mount requires a passphrase to be entered, read it from
              file descriptor passwdfd instead of from the terminal. If  mount
              uses encrypted loop device and gpgkey= mount option is not being
              used (no gpg key file), then mount attempts to read 65 keys from
              passwdfd,  each  key  at  least  20  characters and separated by
              newline. If mount successfully reads 64 or 65  keys,  then  loop
              device is put to multi-key mode. If mount encounters end-of-file
              before 64 keys are read, then only first key is used in  single-
              key mode.

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

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

       -f     Causes  everything to be done except for the actual system call;
              if it’s not obvious, this ‘‘fakes’’ mounting  the  file  system.
              This  option  is  useful  in  conjunction  with  the  -v flag to
              determine what the mount command is trying to do. It can also be
              used  to  add entries for devices that were mounted earlier with
              the -n option. The -f  option  checks  for  existing  record  in
              /etc/mtab and fails when the record already exists (with regular
              non-fake mount, this check is done by kernel).

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

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

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

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

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

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

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

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

       -t vfstype
              The argument following the -t  is  used  to  indicate  the  file
              system   type.   The  file  system  types  which  are  currently
              supported include: adfs, affs,  autofs,  cifs,  coda,  coherent,
              cramfs,  debugfs,  devpts,  efs,  ext, ext2, ext3, hfs, hfsplus,
              hpfs, iso9660, jfs, minix, msdos, ncpfs, nfs, nfs4, 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 usbdevfs.  Note,  the  real
              list of all supported filesystems depends on your kernel.

              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,
              nfs4, cifs, smbfs, ncpfs) ad hoc code  is  necessary.  The  nfs,
              nfs4,  cifs,  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.  Mount uses the  blkid
              or  volume_id  library for guessing the filesystem type; 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 afterwards.

              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
              recognize the wrong filesystem type, possibly with  catastrophic
              consequences.  If  your  data  is  valuable,  don’t ask mount to
              guess.

              More than one type may be specified in a comma  separated  list.
              The list of file system types can be prefixed with no to 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.

              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, fat, vfat and ufs):

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

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

              auto   Can be mounted with the -a option.

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

              dev    Interpret character or block special devices on the  file
                     system.

              exec   Permit execution of binaries.

              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).

              _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).

              nodiratime
                     Do not  update  directory  inode  access  times  on  this
                     filesystem.

              relatime
                     Update  inode  access  times relative to modify or change
                     time.  Access time is only updated if the previous access
                     time  was earlier than the current modify or change time.
                     (Similar to noatime, but  doesn’t  break  mutt  or  other
                     applications  that  need  to know if a file has been read
                     since the last time it was modified.)

              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  /
                     2.6.0.)

              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
                     owner,dev,suid).

              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.

              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.
                     In case of media with  limited  number  of  write  cycles
                     (e.g.  some  flash  drives)  "sync"  may cause life-cycle
                     shortening.

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

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

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

              context=context, fscontext=context and defcontext=context
                     The  context=  option is useful when mounting filesystems
                     that do not support extended attributes, such as a floppy
                     or hard disk formatted with VFAT, or systems that are not
                     normally running under SELinux, such as an ext3 formatted
                     disk  from  a  non-SELinux  workstation. You can also use
                     context= on filesystems you  do  not  trust,  such  as  a
                     floppy.  It  also  helps  in  compatibility  with  xattr-
                     supporting  filesystems   on   earlier   2.4.<x>   kernel
                     versions.  Even  where xattrs are supported, you can save
                     time not having to label  every  file  by  assigning  the
                     entire disk one security context.

                     A   commonly   used   option   for   removable  media  is
                     context=system_u:object_r:removable_t.

                     Two other options are fscontext= and defcontext=, both of
                     which  are mutually exclusive of the context option. This
                     means you can use  fscontext  and  defcontext  with  each
                     other, but neither can be used with context.

                     The   fscontext=   option   works  for  all  filesystems,
                     regardless of their xattr support. The  fscontext  option
                     sets  the  overarching  filesystem  label  to  a specific
                     security context. This filesystem label is separate  from
                     the  individual  labels  on  the files. It represents the
                     entire filesystem for certain kinds of permission checks,
                     such  as  during mount or file creation.  Individual file
                     labels are still obtained from the xattrs  on  the  files
                     themselves.   The   context   option  actually  sets  the
                     aggregate context that fscontext provides, in addition to
                     supplying the same label for individual files.

                     You  can  set  the default security context for unlabeled
                     files using defcontext= option. This overrides the  value
                     set for unlabeled files in the policy and requires a file
                     system that supports xattr labeling.

                     For more details see selinux(8)

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

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

FILESYSTEM SPECIFIC MOUNT OPTIONS

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

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

Mount options for adfs

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

       ownmask=value and othmask=value
              Set the permission mask for ADFS ’owner’ permissions and ’other’
              permissions,   respectively    (default:    0700    and    0077,
              respectively).                      See                     also
              /usr/src/linux/Documentation/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  disregarding  the
              original permissions.  Add search permission to directories that
              have read permission.  The value is given in octal.

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

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

       verbose
              Print an informational message for each successful mount.

       prefix=string
              Prefix used before volume name, when following a link.

       volume=string
              Prefix  (of  length at most 30) used before ’/’ when following a
              symbolic link.

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

       root=value
              Give explicitly the location of the root block.

       bs=value
              Give blocksize. Allowed values are 512, 1024, 2048, 4096.

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

Mount options for cifs

       See the options section  of  the  mount.cifs(8)  man  page  (cifs-mount
       package must be installed).

Mount options for coherent

       None.

Mount options for debugfs

       The  debugfs file system is a pseudo file system, traditionally mounted
       on /sys/kernel/debug.  There are no mount options.

Mount options for devpts

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

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

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

Mount options for ext

       None.  Note that the ‘ext’ file  system  is  obsolete.  Don’t  use  it.
       Since  Linux  version  2.1.21  extfs  is  no  longer part of the kernel
       source.

Mount options for ext2

       The ‘ext2’ file system is the standard Linux file system.  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
              behaviour is to return in the f_blocks field the total number of
              blocks of the file system, while the bsddf behaviour  (which  is
              the default) is to subtract the overhead blocks used by the ext2
              file system and not available for file storage. Thus

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

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

       check=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
              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; 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.)

       nouid32
              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
              default.

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

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

       journal=update
              Update the ext3 file system’s journal to the current 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 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.
              rootflags=data=journal.

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

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

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

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

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

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

Mount options for fat

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

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

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

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

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

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

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

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

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

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

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

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

              binary no translation is performed.  This is the default.

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

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

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

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

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

       cvf_option=option
              Option passed to the CVF module.

       debug  Turn  on  the  debug  flag.  A version string and a 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 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
              process.

       session=n
              Select the CDROM session to mount.   Defaults  to  leaving  that
              decision  to  the  CDROM  driver.   This  option  will fail with
              anything 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.)

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

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

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

       nocheck
              Do not abort mounting when certain consistency checks fail.

Mount options for iso9660

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

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

       Rock Ridge is an extension to iso9660 that provides all of  these  unix
       like features.  Basically there are extensions to each directory record
       that supply all of the additional information, and when Rock  Ridge  is
       in  use,  the  filesystem  is indistinguishable from a normal UNIX file
       system (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 information found in the Rock Ridge
              extensions.  (Default: uid=0,gid=0.)

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

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

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

       block=[512|1024|2048]
              Set   the   block   size  to  the  indicated  value.   (Default:
              block=1024.)

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

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

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

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

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

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

Mount options for jfs

       iocharset=name
              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=value
              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
              keyword  with  no value will grow the volume to the full size of
              the partition.

       nointegrity
              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.

       integrity
              Default.   Commit  metadata  changes  to  the journal.  Use this
              option to remount a volume  where  the  nointegrity  option  was
              previously 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
              continue,  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

       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 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
       constructed by ncpmount(8) and the current version of mount (2.12) does
       not know anything about ncpfs.

Mount options for nfs and nfs4

       See  the options section of the nfs(5) man page (nfs-utils package must
       be installed).

       The nfs and nfs4 implementation expects a  binary  argument  (a  struct
       nfs_mount_data)  to the mount system call. This argument is constructed
       by mount.nfs(8) and the current version of mount (2.13) does  not  know
       anything about nfs and nfs4.

Mount options for ntfs

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

       nls=name
              New name for the option earlier called iocharset.

       utf8   Use UTF-8 for converting file names.

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

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

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

Mount options for proc

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

Mount options for ramfs

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

Mount options for reiserfs

       Reiserfs is a journaling filesystem.  The reiserfs  mount  options  are
       more fully described at http://www.namesys.com/mount-options.html.

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

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

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

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

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

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

       nolog  Disable   journalling.  This  will  provide  slight  performance
              improvements in some situations at the cost of losing 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.

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

       resize=number
              A remount option which  permits  online  expansion  of  reiserfs
              partitions.   Instructs  reiserfs  to assume that the device has
              number blocks.  This option is designed  for  use  with  devices
              which  are  under  logical  volume management (LVM).  There is a
              special   resizer   utility   which   can   be   obtained   from
              ftp://ftp.namesys.com/pub/reiserfsprogs.

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

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

Mount options for romfs

       None.

Mount options for smbfs

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

Mount options for sysv

       None.

Mount options for tmpfs

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

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

       nr_blocks=
              Set number of blocks.

       nr_inodes=
              Set number of inodes.

       mode=  Set initial permissions of the root directory.

Mount options for udf

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

       gid=   Set the default group.

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

       uid=   Set the default user.

       unhide Show otherwise hidden files.

       undelete
              Show deleted files in lists.

       nostrict
              Unset strict conformance.

       iocharset
              Set the NLS character set.

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

       novrs  Skip volume sequence recognition.

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

       anchor=
              Override standard anchor location. Default: 256.

       volume=
              Override the VolumeDesc location. (unused)

       partition=
              Override the PartitionDesc location. (unused)

       lastblock=
              Set the last block of the filesystem.

       fileset=
              Override the fileset block location. (unused)

       rootdir=
              Override the root directory location. (unused)

Mount options for ufs

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

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

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

              sun    For filesystems created by SunOS or Solaris on Sparc.

              sunx86 For filesystems created by Solaris on x86.

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

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

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

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

       onerror=value
              Set behaviour on error:

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

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

Mount options for umsdos

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

Mount options for vfat

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

       uni_xlate
              Translate   unhandled  Unicode  characters  to  special  escaped
              sequences.  This lets you backup and restore filenames that  are
              created  with any Unicode characters. Without this option, a ’?’
              is used when no translation is possible. The escape character is
              ’:’  because it is otherwise illegal on the vfat filesystem. The
              escape  sequence  that  gets  used,  where  u  is  the   unicode
              character, is: ’:’, (u & 0x3f), ((u>>6) & 0x3f), (u>>12).

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

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

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

       shortname=[lower|win95|winnt|mixed]

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

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

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

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

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

       The default is "lower".

Mount options for 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

       None.

Mount options for xfs

       allocsize=size
              Sets the buffered I/O end-of-file preallocation size when  doing
              delayed  allocation  writeout  (default  size  is 64KiB).  Valid
              values for this option are page size (typically 4KiB) through to
              1GiB, inclusive, in power-of-2 increments.

       attr2 / noattr2
              The  options  enable/disable  (default  is disabled for backward
              compatibility on-disk) an "opportunistic" improvement to be made
              in  the way inline extended attributes are stored on-disk.  When
              the new form is used for the first time (by setting or  removing
              extended  attributes)  the  on-disk superblock feature bit field
              will be updated to reflect this format being in use.

       barrier
              Enables the use of block layer write barriers  for  writes  into
              the  journal  and  unwritten extent conversion.  This allows for
              drive level write  caching  to  be  enabled,  for  devices  that
              support write barriers.

       dmapi  Enable the DMAPI (Data Management API) event callouts.  Use with
              the mtpt option.

       grpid / bsdgroups and nogrpid / 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.

       ihashsize=value
              Sets  the  number  of hash buckets available for hashing the in-
              memory inodes of the specified mount point.  If a value of  zero
              is  used,  the  value  selected by the default algorithm will be
              displayed in /proc/mounts.

       ikeep / noikeep
              When inode clusters are emptied of inodes, keep them  around  on
              the  disk (ikeep) - this is the traditional XFS behaviour and is
              still the default for now.   Using  the  noikeep  option,  inode
              clusters are returned to the free space pool.

       inode64
              Indicates  that  XFS is allowed to create inodes at any location
              in the filesystem, including those which will  result  in  inode
              numbers  occupying  more  than 32 bits of significance.  This is
              provided for backwards compatibility, but  causes  problems  for
              backup applications that cannot handle large inode numbers.

       largeio / nolargeio
              If   nolargeio   is  specified,  the  optimal  I/O  reported  in
              st_blksize by stat(2) will be as small as possible to allow user
              applications  to  avoid  inefficient  read/modify/write I/O.  If
              largeio is specified, a filesystem that has a  swidth  specified
              will  return  the  swidth value (in bytes) in st_blksize. If the
              filesystem does not have a swidth specified but does specify  an
              allocsize  then  allocsize  (in bytes) will be returned instead.
              If neither of these two options are specified,  then  filesystem
              will behave as if nolargeio was specified.

       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 64KiB, 4 buffers for filesystems
              with a blocksize of 32KiB, 3  buffers  for  filesystems  with  a
              blocksize  of  16KiB 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.

       logbsize=value
              Set the  size  of  each  in-memory  log  buffer.   Size  may  be
              specified  in  bytes,  or in kilobytes with a "k" suffix.  Valid
              sizes for version 1 and version 2 logs are 16384 (16k) and 32768
              (32k).  Valid sizes for version 2 logs also include 65536 (64k),
              131072 (128k) and 262144 (256k).  The default value for machines
              with  more  than  32MiB  of  memory is 32768, machines with less
              memory use 16384 by default.

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

       mtpt=mountpoint
              Use with the dmapi option. The  value  specified  here  will  be
              included in the DMAPI mount event, and should be the path of the
              actual mountpoint that is used.

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

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

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

       nouuid Don’t check for double  mounted  file  systems  using  the  file
              system uuid.  This is useful to mount LVM snapshot volumes.

       osyncisdsync
              Make  O_SYNC writes implement true O_SYNC.  WITHOUT this option,
              Linux XFS behaves as if an osyncisdsync option  is  used,  which
              will 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 not in effect, timestamp updates  from  O_SYNC
              writes  can be lost if the system crashes.  If timestamp updates
              are critical, use the osyncisosync option.

       uquota / usrquota / uqnoenforce / quota
              User disk quota  accounting  enabled,  and  limits  (optionally)
              enforced.  Refer to xfs_quota(8) for further details.

       gquota / grpquota / gqnoenforce
              Group  disk  quota  accounting  enabled  and limits (optionally)
              enforced. Refer to xfs_quota(8) for further details.

       pquota / prjquota / pqnoenforce
              Project disk quota accounting enabled  and  limits  (optionally)
              enforced. Refer to xfs_quota(8) for further details.

       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.

       swalloc
              Data  allocations  will be rounded up to stripe width boundaries
              when the current end of file is being extended and the file size
              is larger than the stripe width size.

Mount options for xiafs

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

THE LOOP DEVICE

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

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

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

       This  type  of  mount  knows  about  11  options,  namely loop, offset,
       sizelimit,  encryption,  pseed,   phash,   loinit,   gpgkey,   gpghome,
       cleartextkey  and  itercountk  that  are  really options to losetup(8).
       (These options can be  used  in  addition  to  those  specific  to  the
       filesystem type.)

       If the mount requires a passphrase, you will be prompted for one unless
       you specify a file descriptor to read from instead with the -p  command
       line option, or specify a file name with cleartextkey mount option.  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).

RETURN CODES

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

       0      success

       1      incorrect invocation or permissions

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

       4      internal mount bug

       8      user interrupt

       16     problems writing or locking /etc/mtab

       32     mount failure

       64     some mount succeeded

NOTES

       The syntax of external mount helpers is:

       /sbin/mount.<suffix> spec dir [-sfnv] [-o options]

       where  the  <suffix>  is  filesystem  type and -sfnvo options have same
       meaning like standard mount options.

FILES

       /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

SEE ALSO

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

BUGS

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

       Some Linux file systems don’t support -o sync and -o dirsync (the ext2,
       ext3,  fat  and  vfat 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.

       It is possible that files /etc/mtab and /proc/mounts don’t  match.  The
       first  file is based only on the mount command options, but the content
       of the second file also depends on the kernel and others settings (e.g.
       remote  NFS  server.  In  particular case the mount command may reports
       unreliable information about a NFS mount  point  and  the  /proc/mounts
       file usually contains more reliable information.)

       Checking  files  on NFS filesystem referenced by file descriptors (i.e.
       the fcntl and ioctl families of functions)  may  lead  to  inconsistent
       result  due  to the lack of consistency check in kernel even if noac is
       used.

HISTORY

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

AVAILABILITY

       The mount command is part of the util-linux-ng package and is available
       from ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/.