Name
umount — unmount file systems
Synopsis
umount −a [−dflnrv] [ −t vfstype ] [ −O options ]
umount [−dflnrv] dir | device [ ... ]
DESCRIPTION
The umount
command detaches the file system(s) mentioned from the file
hierarchy. A file system is specified by giving the directory
where it has been mounted. Giving the special device on which
the file system lives may also work, but is obsolete, mainly
because it will fail in case this device was mounted on more
than one directory.
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. A lazy unmount avoids this problem.
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.
−i-
Don't call the /sbin/umount.<filesystem>
helper even if it exists. By default
/sbin/umount.<filesystem> helper is called if one
exists.
−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 one option type
may be specified in a comma separated list. Each option
can be prefixed with no to specify options
for which no action should be taken.
−f-
Force unmount (in case of an unreachable NFS
system). (Requires kernel 2.1.116 or later.)
−l-
Lazy unmount. Detach the filesystem from the
filesystem hierarchy now, and cleanup all references to
the filesystem as soon as it is not busy anymore.
(Requires kernel 2.4.11 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
HISTORY
A umount
command appeared in Version 6 AT&T UNIX.
Copyright (c) 1996 Andries Brouwer
This page is somewhat derived from a page that was
(c) 1980, 1989, 1991 The Regents of the University of California
and had been heavily modified by Rik Faith and myself.
This is free documentation; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of
the License, or (at your option) any later version.
The GNU General Public License's references to "object code"
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This manual is distributed in the hope that it will be useful,
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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You should have received a copy of the GNU General Public
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