.\" 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" .\" and "executables" are to be interpreted as the output of any .\" document formatting or typesetting system, including .\" intermediate and printed output. .\" .\" This manual is distributed in the hope that it will be useful, .\" but WITHOUT ANY WARRANTY; without even the implied warranty of .\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the .\" GNU General Public License for more details. .\" .\" You should have received a copy of the GNU General Public License along .\" with this program; if not, write to the Free Software Foundation, Inc., .\" 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. .\" .TH UMOUNT 8 "August 2012" "util-linux" "System Administration" .SH NAME umount \- unmount file systems .SH SYNOPSIS .B umount .RB [ \-hV ] .LP .B umount \-a .RB [ \-dflnrv ] .RB [ \-t .IR fstype ] .RB [ \-O .IR options ] .br .B umount .RB [ \-dflnrv ] .RI { dir | device }... .SH DESCRIPTION The .B umount command detaches the mentioned file system(s) 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 Giving the special device on which the file system lives may also work, but is obsolete, mainly because it will fail in case this device was mounted on more than one directory. .PP 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 .B umount itself - it opens libc, and libc in its turn may open for example locale files. A lazy unmount avoids this problem. .SH OPTIONS .TP \fB\-a\fR, \fB\-\-all\fR All of the filesystems described in .I /etc/mtab are unmounted. (With .B umount version 2.7 and later: the .I proc filesystem is not unmounted.) .TP \fB\-A\fR, \fB\-\-all-targets\fR Unmount all mountpoints in the current namespace for the specified filesystem. The filesystem could be specified by one of the mountpoints or device name (or UUID, etc.). This option could be used together with \fB\-\-recursive\fR then all nested mounts within the filesystem are recursively unmounted. The \fB\-\-all-targets\fR is only supported on systems where /etc/mtab is a symlink to /proc/mounts. .TP \fB\-c\fR, \fB\-\-no\-canonicalize\fR Do not canonicalize paths. For more details about this option see the .BR mount (8) man page. Note that umount(8) does not pass this option to /sbin/umount. helpers. .TP \fB\-d\fR, \fB\-\-detach\-loop\fR In case the unmounted device was a loop device, also free this loop device. .TP \fB\-\-fake\fP Causes everything to be done except for the actual system call; this 'fakes' unmounting the filesystem. It can be used to remove entries from .I /etc/mtab that were unmounted earlier with the .B \-n option. .TP \fB\-f\fR, \fB\-\-force\fR Force unmount (in case of an unreachable NFS system). (Requires kernel 2.1.116 or later.) .TP \fB\-i\fR, \fB\-\-internal\-only\fR Do not call the /sbin/umount. helper even if it exists. By default /sbin/umount. helper is called if one exists. .TP \fB\-n\fR, \fB\-\-no\-mtab\fR Unmount without writing in .IR /etc/mtab . .TP \fB\-l\fR, \fB\-\-lazy\fR 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.) .TP \fB\-O\fR, \fB\-\-test\-opts\fR \fIoption\fR Indicate that the actions should only be taken on filesystems with the specified option in .IR /etc/fstab . More than one option may be specified in a comma-separated list. Each option can be prefixed with .B no to specify options for which no action should be taken. .TP \fB\-R\fR, \fB\-\-recursive\fR Recursively unmount each directory specified. Recursion for each directory will stop if any unmount operation in the chain fails for any reason. The relationship between mountpoints is determined by /proc/self/mountinfo entries. The filesystem must be specified by mountpoint path, recursive unmount by device name (or UUID) is unsupported. .TP \fB\-r\fR, \fB\-\-read\-only\fR In case unmounting fails, try to remount read-only. .TP \fB\-t\fR, \fB\-\-types\fR \fItype\fR Indicate that the actions should only be taken on filesystems of the specified .IR type . More than one type may be specified in a comma-separated list. The list of filesystem types can be prefixed with .B no to specify the types of filesystem on which no action should be taken. .TP \fB\-v\fR, \fB\-\-verbose\fR Verbose mode. .TP \fB\-h\fR, \fB\-\-help\fR Display help text and exit. .TP \fB\-V\fR, \fB\-\-version\fR Display version information and exit. .SH "THE LOOP DEVICE" The .B umount command will free the loop device (if any) associated with the mount, in case it finds the option 'loop=...' in .IR /etc/mtab , or when the \-d option was given. Any pending loop devices can be freed using 'losetup -d', see .BR losetup (8). .SH "EXTERNAL HELPERS" The syntax of external umount helpers is: .PP .BI /sbin/umount. .RI { dir | device } .RB [ \-nlfvr ] .RB [ \-t .IR type.subtype ] .PP where the is filesystem type or a value from "uhelper=" or "helper=" mtab option. The \-t option is used for filesystems with subtypes support (for example /sbin/mount.fuse -t fuse.sshfs). .PP The uhelper= (unprivileged umount helper) is possible to use when non-root user wants to umount a mountpoint which is not defined in the /etc/fstab file (e.g. devices mounted by udisk). .PP The helper= mount option redirects all umount requests to the /sbin/umount. independently on UID. .SH FILES .I /etc/mtab table of mounted filesystems .SH ENVIRONMENT .IP LIBMOUNT_FSTAB= overrides the default location of the fstab file .IP LIBMOUNT_MTAB= overrides the default location of the mtab file .IP LIBMOUNT_DEBUG=0xffff enables debug output .SH "SEE ALSO" .BR umount (2), .BR mount (8), .BR losetup (8) .SH HISTORY A .B umount command appeared in Version 6 AT&T UNIX. .SH AVAILABILITY The umount command is part of the util-linux package and is available from .UR ftp://\:ftp.kernel.org\:/pub\:/linux\:/utils\:/util-linux/ Linux Kernel Archive .UE .