bsd man page for umount

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

NAME
       umount - unmount file systems

SYNOPSIS
       umount [ -fv ] special | node
       umount -a [ -fv ] [ -t ufs | external_type ]

DESCRIPTION
       The  umount command calls the umount(2) system call to remove a special device from the file system tree at the point node.  If either spe-
       cial or node are not provided, the appropriate information is taken from the fstab(5) file.

       The options are as follows:

       -a	 All of the file systems described in fstab(5) 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.  This is not currently implemented in 2.11BSD.

       -t ufs | external type
		 Is  used  to indicate 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 specify the filesystem types for which action
		 should not be taken.  For example, the umount command:

		 umount -a -t nfs,mfs

		 umounts all filesystems of the type NFS and MFS.

		 NOTE: Only UFS is supported by 2.11BSD.  The example is for illustrative purposes only.

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

FILES
       /etc/fstab     file system table

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

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

4.4 Berkeley Distribution					 January 16, 1996							 UMOUNT(8)