umount - unmount file systems
SYNOPSIS
umount [-hV]
umount -a [-nrv] [-t vfstype] [-O options]
umount [-nrv] device | dir [...]
DESCRIPTION
The umount command detaches the file system(s) mentioned
from the file hierarchy. A file system is specified
either by giving the directory where it has been mounted,
or by giving the special device on which it lives.
Note that a file system cannot be unmounted when it is
`busy' - for example, when there are open files on it, or
when some process has its working directory there, or when
a swap file on it is in use. The offending process could
even be umount itself - it opens libc, and libc in its
turn may open for example locale files.
Options for the umount command:
-V Print version and exit.
-h Print help message and exit.
-v Verbose mode.
-n Unmount without writing in /etc/mtab.
-r In case unmounting fails, try to remount read-only.
-d In case the unmounted device was a loop device,
also free this loop device.
-a All of the file systems described in /etc/mtab are
unmounted. (With umount version 2.7 and later: the
proc filesystem is not unmounted.)
-t vfstype
Indicate that 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 on which no
action should be taken.
-O options
Indicate that the actions should only be taken on
file systems with the specified options in
/etc/fstab. More than option type may be specified
in a comma separated list. Each option can be
action should be taken.
-f Force unmount (in case of an unreachable NFS sys
tem). (Requires kernel 2.1.116 or later.)
THE LOOP DEVICE
The umount command will free the loop device (if any)
associated with the mount, in case it finds the option
`loop=...' in /etc/mtab, or when the -d option was given.
Any pending loop devices can be freed using `losetup -d',
see losetup(8).
FILES
/etc/mtab table of mounted file systems
SEE ALSO
umount(2), mount(8), losetup(8).
HISTORY
A umount command appeared in Version 6 AT&T UNIX.
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