| UMOUNT(8) | System Manager's Manual | UMOUNT(8) | 
umount —
| umount | [ -fvFR] [-tfstypelist] special |
      node | 
| umount | -a[-fvF]
      [-hhost]
      [-tfstypelist] | 
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-f-F-v, to see what umount
      would attempt to do).-R-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-a option and, unless otherwise
      specified with the -t option, will only unmount
      NFS file systems.-t
    fstypelistumount 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.
-vumount command appeared in
  Version 1 AT&T UNIX.
| September 12, 2016 | NetBSD 10.1 |