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

NAME
     umount — unmount file systems

SYNOPSIS
     umount [-fv] special ... | node ... | fsid ...
     umount -a | -A [-F fstab] [-fv] [-h host] [-t type]

DESCRIPTION
     The umount utility calls the unmount(2) system call to remove a file sys‐
     tem from the file system tree.  The file system can be specified by its
     special device or remote node (rhost:path), the path to the mount point
     node or by the file system ID fsid as reported by “mount -v” when run by
     root.

     The options are as follows:

     -a      All the file systems described in fstab(5) are unmounted.

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

     -F fstab
	     Specify the fstab file to use.

     -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.  For NFS, a forced dismount can take up to 1 minute or
	     more to complete against an unresponsive server and may throw
	     away data not yet written to the server for this case.  Also,
	     doing a forced dismount of an NFSv3 mount when rpc.lockd(8) is
	     running is unsafe and can result in a crash.

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

     -t type
	     Is used to indicate the actions should only be taken on file sys‐
	     tems 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,nullfs

	     unmounts all file systems of the type NFS and NULLFS that are
	     listed in the fstab(5) file.

     -v      Verbose, additional information is printed out as each file sys‐
	     tem is unmounted.

ENVIRONMENT
     PATH_FSTAB  If the environment variable PATH_FSTAB is set, all operations
		 are performed against the specified file.  PATH_FSTAB will
		 not be honored if the process environment or memory address
		 space is considered “tainted”.  (See issetugid(2) for more
		 information.)

FILES
     /etc/fstab  file system table

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

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

BSD				 June 17, 2015				   BSD