UMOUNT(T)           Linux Programmer's Manual           UMOUNT(T)



NAME
       umount - unmount file systems

SYNOPSIS
       umount [-hV]

       umount -a [-dflnrv] [-t vfstype]
       umount [-dflnrv] dir | device [...]

DESCRIPTION
       The  umount  command detaches the file system(m) mentioned
       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       work, but is obsolete, mainly because it will fail in case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 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.

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

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


FILES
       /etc/mtab table of mounted file systems


SEE ALSO
       umount(t), mount(t), losetup(p).


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



Linux 2.0                  26 July 1997                 UMOUNT(T)