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UMOUNT(8)                   System Manager's Manual                  UMOUNT(8)

NAME
     umount - unmount file systems

SYNOPSIS
     umount [-fvFR] [-t fstypelist] special | node
     umount -a [-fvF] [-h host] [-t fstypelist]

DESCRIPTION
     The umount command calls the unmount(2) system call (or an external
     unmount program) to remove a special device or the remote node
     (rhost:path) from the file system tree at the point node.  If either
     special or node are not provided, the appropriate information is taken
     from the fstab(5) file.

     By default, the file system type is extracted from the kernel and used to
     choose an external unmount program, whose name is formed by appending an
     underscore and the type string to "umount".  This matches the form used
     by the external mount programs used by mount(8).  If this program is
     found on the path, it is used in preference to calling unmount(2)
     directly.  Note that in the NetBSD base system no such external unmount
     programs exist; the facility is provided in the hopes that it will be
     useful for third party file systems and/or for research.

     The options are as follows:

     -a      All the currently mounted file systems except the root are
             unmounted.

     -f      The file system is forcibly unmounted.  Active special devices
             continue to work, but all other files return errors if further
             accesses are attempted.  The root file system cannot be forcibly
             unmounted.

     -F      Fake the unmount; perform all other processing but do not
             actually attempt the unmount.  (This is most useful in
             conjunction with -v, to see what umount would attempt to do).

     -R      Take the special | node argument as a path to be passed directly
             to unmount(2), bypassing all attempts to be smart about
             mechanically determining the correct path from the argument.
             This option is incompatible with any option that potentially
             unmounts more than one file system, such as -a, but it can be
             used with -f and/or -v.  This is the only way to unmount
             something that does not appear as a directory (such as a nullfs
             mount of a plain file); there are probably other cases where it
             is necessary.  This option also disables the use of any external
             unmount program.

     -h host
             Only file systems mounted from the specified host will be
             unmounted.  This option implies the -a option and, unless
             otherwise specified with the -t option, will only unmount NFS
             file systems.

     -t fstypelist
             Is used to indicate 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
             for which action should not be taken.  For example, the umount
             command:

                   umount -a -t nfs,mfs

             unmounts all file systems of the type NFS and MFS, whereas the
             umount command:

                   umount -a -t nonfs,mfs

             unmounts all file systems except those of type NFS and MFS.

     -v      Verbose, additional information is printed out as each file
             system is unmounted.

FILES
     /etc/fstab  file system table

SEE ALSO
     unmount(2), fstab(5), mount(8)

HISTORY
     A umount command appeared in Version 1 AT&T UNIX.

NetBSD 10.99                  September 12, 2016                  NetBSD 10.99