The
umount
utility calls the
unmount(2)
system call to remove a file system from the file system tree.
The file system can be specified by its
special
device or remote node
(
rhost amp;: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 are unmounted,
except for those mounted at
/
or
/dev.
|
| -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.
If a process, such as
umount
without the
-f
flag is hung on an
NFS
mount point, use the
-N
flag instead.
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 otherwise specified with the
-t
option, will only unmount
NFS
file systems.
|
| -N
|
| |
Do a forced dismount of an
NFS
mount point without checking the mount path.
This option can only be used with the path to the mount point
node
and the path must be specified exactly as it was at mount time.
This option is useful when a process is hung waiting for an unresponsive
NFS
server while holding a vnode lock on the mounted-on vnode, such that
umount
with the
-f
flag can't complete.
Using this option can result in a loss of file updates that have not been
flushed to the
NFS
server.
|
| -n
|
| |
Unless the
-f
is used, the
umount
will not unmount an active file system.
It will, however, perform a flush.
This flag disables this behaviour, preventing the flush
if there are any files open.
|
| -t type
|
| |
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,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 system
is unmounted.
|
|
