umount - unmount file systems


SYNOPSIS

       umount [-hV]

       umount -a [-nrv] [-t vfstype] [-O options]
       umount [-nrv] device | dir [...]


DESCRIPTION

       The  umount  command detaches the file system(s) mentioned
       from the file  hierarchy.   A  file  system  is  specified
       either  by giving the directory where it has been mounted,
       or by giving the special device on which it lives.

       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.

       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.

       -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 specified 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 option type may be specified
              in  a  comma  separated  list.   Each option can be

              action should be taken.

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


THE LOOP DEVICE

       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).


FILES

       /etc/mtab table of mounted file systems


SEE ALSO

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


HISTORY

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


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