NAME

       umount - unmount file systems

SYNOPSIS

       umount -a [-dflnrv] [-t fstype] [-O option...]

       umount [-dflnrv] {directory|device}...

       umount -h|-V

DESCRIPTION

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       system  lives may also work, but is obsolete, mainly because it will fail in case this device was mounted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

       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

       -a, --all
              All of the filesystems described in /etc/mtab are unmounted, except the proc filesystem.

       -A, --all-targets
              Unmount all mountpoints in the current namespace for the specified filesystem.  The filesystem can
              be specified by one of the mountpoints or the device name (or UUID, etc.).  When  this  option  is
              used  together  with  --recursive,  then  all  nested mounts within the filesystem are recursively
              unmounted.  This option is only supported on systems where /etc/mtab is a symlink to /proc/mounts.

       -c, --no-canonicalize
              Do not canonicalize paths.  For more details about this option see the mount(8)  man  page.   Note
              that umount does not pass this option to the /sbin/umount.type helpers.

       -d, --detach-loop
              When the unmounted device was a loop device, also free this loop device.

       --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 option.

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

       -i, --internal-only
              Do  not  call  the  /sbin/umount.filesystem  helper  even  if it exists.  By default such a helper
              program is called if it exists.

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

       -n, --no-mtab
              Unmount without writing in /etc/mtab.

       -O, --test-opts option...
              Unmount  only  the  filesystems  that  have the specified option set in /etc/fstab.  More than one
              option may be specified in a comma-separated list.   Each  option  can  be  prefixed  with  no  to
              indicate that no action should be taken for this option.

       -R, --recursive
              Recursively  unmount  each  specified  directory.   Recursion  for each directory will stop if any
              unmount operation in the chain fails for any reason.   The  relationship  between  mountpoints  is
              determined  by /proc/self/mountinfo entries.  The filesystem must be specified by mountpoint path;
              a recursive unmount by device name (or UUID) is unsupported.

       -r, --read-only
              When an unmount fails, try to remount the filesystem read-only.

       -t, --types type...
              Indicate that the actions should only be taken on filesystems of the specified  type.   More  than
              one type may be specified in a comma-separated list.  The list of filesystem types can be prefixed
              with no to indicate that no action should be taken for all of the mentioned types.

       -v, --verbose
              Verbose mode.

       -V, --version
              Display version information and exit.

       -h, --help
              Display help text and exit.

LOOP DEVICE

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

EXTERNAL HELPERS

       The syntax of external unmount helpers is:

              umount.suffix {directory|device} [-flnrv] [-t type.subtype]

       where suffix is the filesystem type (or the value from a uhelper= or helper= marker in  the  mtab  file).
       The -t option can be used for filesystems that have subtype support.  For example:

              umount.fuse -t fuse.sshfs

       A  uhelper=something  marker  (unprivileged  helper) can appear in the /etc/mtab file when ordinary users
       need to be able to unmount a mountpoint that is not defined in /etc/fstab (for example for a device  that
       was mounted by udisks(1)).

       A  helper=type marker in the mtab file will redirect all unmount requests to the /sbin/umount.type helper
       independently of UID.

FILES

       /etc/mtab
              table of mounted filesystems

       /etc/fstab
              table of known filesystems

ENVIRONMENT

       LIBMOUNT_FSTAB=<path>
              overrides the default location of the fstab file (ignored for suid)

       LIBMOUNT_MTAB=<path>
              overrides the default location of the mtab file (ignored for suid)

       LIBMOUNT_DEBUG=all
              enables libmount debug output

SEE ALSO

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

HISTORY

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

AVAILABILITY

       The umount command is part of the util-linux package and is available from Linux Kernel  Archive  ⟨ftp://
       ftp.kernel.org/pub/linux/utils/util-linux/⟩.