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

       umount - unmount file systems

       umount [-hV]

       umount -a [-dflnrv] [-t vfstype] [-O options]
       umount [-dflnrv] {dir|device}...

       The  umount  command detaches the file system(s) mentioned from the file hierarchy.
       A file system is specified by giving the directory where it has been mounted.  Giv-
       ing  the  special device on which the file system lives may also work, but is obso-
       lete, mainly because it will fail in case this device was mounted on more than  one

       Note  that  a file system cannot be unmounted when it is 'busy' - for example, when
       there are open files on it, or when some process has its working  directory  there,
       or  when  a  swap file on it is in use.  The offending process could even be umount
       itself - it opens libc, and libc in its turn may open for example locale files.   A
       lazy unmount avoids this problem.

       Options for the umount command:

       -V     Print version and exit.

       -h     Print help message and exit.

       -v     Verbose mode.

       -n     Unmount without writing in /etc/mtab.

       -r     In case unmounting fails, try to remount read-only.

       -d     In  case the unmounted device was a loop device, also free this loop device.

       -i     Don't call the  /sbin/umount.<filesystem>  helper  even  if  it  exists.  By
              default /sbin/umount.<filesystem> helper is called if one exists.

       -a     All  of  the file systems described in /etc/mtab are unmounted. (With umount
              version 2.7 and later: the proc filesystem is not unmounted.)

       -t vfstype
              Indicate that the actions should only be taken on file systems of the speci-
              fied  type.   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.

       -O options
              Indicate  that  the  actions  should  only be taken on file systems with the
              specified options in /etc/fstab.  More than one option type may be specified
              in  a  comma separated list.  Each option can be prefixed with no to specify
              options for which no action should be taken.

       -f     Force unmount (in case of an  unreachable  NFS  system).   (Requires  kernel
              2.1.116 or later.)

       -l     Lazy  unmount.  Detach the filesystem from the filesystem hierarchy now, and
              cleanup all references to the filesystem as soon as it is not busy  anymore.
              (Requires kernel 2.4.11 or later.)

              Don't  canonicalize  paths.  For  more  details  about  this  option see the
              mount(8) man page.

       --fake Causes everything to be done except for the actual  system  call  or  umount
              helper execution; this ''fakes'' unmounting the filesystem.  It can  be used
              to remove entries from /etc/mtab that were unmounted  earlier  with  the  -n

       The umount command will free the loop device (if any) associated with the mount, in
       case it finds the option 'loop=...' in /etc/mtab, or when the -d option was  given.
       Any pending loop devices can be freed using 'losetup -d', see losetup(8).

       The syntax of external umount helpers is:

       /sbin/umount.<suffix> {dir|device} [-nlfvr] [-t type.subtype]

       where  the <suffix> is filesystem type or a value from "uhelper=" mtab option.  The
       -t  option  is  used   for  filesystems  with   subtypes   support   (for   example
       /sbin/mount.fuse -t fuse.sshfs).

       The  uhelper  (unprivileged  umount  helper) is possible to used when non-root user
       wants to umount a mountpoint which is not  defined  in  the  /etc/fstab  file  (e.g
       devices mounted by HAL).

       /etc/mtab table of mounted file systems

       umount(2), mount(8), losetup(8).

       A umount command appeared in Version 6 AT&T UNIX.

       The  umount  command  is  part  of  the util-linux-ng package and is available from

Linux 2.0                        26 July 1997                        UMOUNT(8)

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