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UMOUNT(8) NetBSD System Manager's Manual UMOUNT(8)
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umount -- unmount file systems
umount [-fvFR] [-t fstypelist] special | node
umount -a [-fvF] [-h host] [-t fstypelist]
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
-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
-F Fake the unmount; perform all other processing but do not actu-
ally 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 mechani-
cally 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 pro-
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
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,mfs
unmounts all file systems of the type NFS and MFS, whereas the
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 sys-
tem is unmounted.
/etc/fstab file system table
unmount(2), fstab(5), mount(8)
A umount command appeared in Version 1 AT&T UNIX.
NetBSD 10.99 September 12, 2016 NetBSD 10.99