unmount file systems
special ... |
node ... |
utility calls the
system call to remove a file system from the file system tree. The file system
can be specified by its special
remote node (rhost:path), the path to the mount point
or by the file system ID
as reported by “mount -v”
when run by root.
The options are as follows:
- All the file systems described in
- All the currently mounted file systems except the root are unmounted.
- Specify the fstab file to use.
- 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,
-N flag instead. Also, doing a
forced dismount of an NFSv3 mount when
is running is unsafe and can result in a crash.
- Only file systems mounted from the specified host will be unmounted. This
option implies the
-A option and,
unless otherwise specified with the
option, will only unmount NFS file systems.
- 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
-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.
- 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.
- 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
unmounts all file systems of the type NFS and NULLFS that are listed in the
- Verbose, additional information is printed out as each file system is
- If the environment variable
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
for more information.)
- file system table
utility appeared in
Version 1 AT&T UNIX