187 lines
5.9 KiB
Groff
187 lines
5.9 KiB
Groff
.\" Copyright (c) 1996 Andries Brouwer
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.\" This page is somewhat derived from a page that was
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.\" (c) 1980, 1989, 1991 The Regents of the University of California
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.\" and had been heavily modified by Rik Faith and myself.
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.\"
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.\" This is free documentation; you can redistribute it and/or
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.\" modify it under the terms of the GNU General Public License as
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.\" published by the Free Software Foundation; either version 2 of
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.\" the License, or (at your option) any later version.
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.\"
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.\" The GNU General Public License's references to "object code"
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.\" and "executables" are to be interpreted as the output of any
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.\" document formatting or typesetting system, including
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.\" intermediate and printed output.
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.\"
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.\" This manual is distributed in the hope that it will be useful,
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.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
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.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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.\" GNU General Public License for more details.
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.\"
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.\" You should have received a copy of the GNU General Public License along
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.\" with this program; if not, write to the Free Software Foundation, Inc.,
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.\" 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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.\"
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.TH UMOUNT 8 "August 2012" "util-linux" "System Administration"
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.SH NAME
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umount \- unmount file systems
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.SH SYNOPSIS
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.B umount
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.RB [ \-hV ]
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.LP
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.B umount \-a
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.RB [ \-dflnrv ]
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.RB [ \-t
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.IR vfstype ]
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.RB [ \-O
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.IR options ]
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.br
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.B umount
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.RB [ \-dflnrv ]
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.RI { dir | device }...
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.SH DESCRIPTION
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The
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.B umount
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command detaches the file system(s) mentioned from the file hierarchy. A
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file system is specified by giving the directory where it has been
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mounted. Giving the special device on which the file system lives may
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also work, but is obsolete, mainly because it will fail in case this
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device was mounted on more than one directory.
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.PP
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Note that a file system cannot be unmounted when it is 'busy' - for
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example, when there are open files on it, or when some process has its
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working directory there, or when a swap file on it is in use. The
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offending process could even be
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.B umount
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itself - it opens libc, and libc in its turn may open for example locale
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files. A lazy unmount avoids this problem.
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.SH OPTIONS
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.TP
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\fB\-a\fR, \fB\-\-all\fR
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All of the file systems described in
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.I /etc/mtab
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are unmounted. (With
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.B umount
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version 2.7 and later: the
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.I proc
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filesystem is not unmounted.)
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.TP
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\fB\-c\fR, \fB\-\-no\-canonicalize\fR
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Do not canonicalize paths. For more details about this option see the
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.BR mount (8)
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man page.
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.TP
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\fB\-d\fR, \fB\-\-detach\-loop\fR
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In case the unmounted device was a loop device, also free this loop
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device.
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.TP
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\fB\-\-fake\fP
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Causes everything to be done except for the actual system call; this 'fakes'
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unmounting the filesystem. It can be used to remove entries from
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.I /etc/mtab
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that were unmounted earlier with the
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.B \-n
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option.
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.TP
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\fB\-f\fR, \fB\-\-force\fR
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Force unmount (in case of an unreachable NFS system). (Requires kernel
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2.1.116 or later.)
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.TP
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\fB\-i\fR, \fB\-\-internal\-only\fR
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Do not call the /sbin/umount.<filesystem> helper even if it exists. By
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default /sbin/umount.<filesystem> helper is called if one exists.
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.TP
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\fB\-n\fR, \fB\-\-no\-mtab\fR
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Unmount without writing in
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.IR /etc/mtab .
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.TP
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\fB\-l\fR, \fB\-\-lazy\fR
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Lazy unmount. Detach the filesystem from the filesystem hierarchy now,
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and cleanup all references to the filesystem as soon as it is not busy
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anymore. (Requires kernel 2.4.11 or later.)
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.TP
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\fB\-O\fR, \fB\-\-test\-opts\fR \fIoptions,list\fR
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Indicate that the actions should only be taken on file systems with the
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specified options in
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.IR /etc/fstab .
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More than one option type may be specified in a comma separated list.
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Each option can be prefixed with
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.B no
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to specify options for which no action should be taken.
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.TP
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\fB\-R\fR, \fB\-\-recursive\fR
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Recursively unmount each directory specified. Recursion for each directory will
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stop if any unmount operation in the chain fails for any reason.
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.TP
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\fB\-r\fR, \fB\-\-read\-only\fR
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In case unmounting fails, try to remount read-only.
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.TP
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\fB\-t\fR, \fB\-\-types\fR \fIvfstype,ext2,ext3\fR
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Indicate that the actions should only be taken on file systems of the
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specified
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.IR type .
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More than one type may be specified in a comma separated list. The list
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of file system types can be prefixed with
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.B no
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to specify the file system types on which no action should be taken.
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.TP
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\fB\-v\fR, \fB\-\-verbose\fR
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Verbose mode.
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.TP
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\fB\-h\fR, \fB\-\-help\fR
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Print help message and exit.
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.TP
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\fB\-V\fR, \fB\-\-version\fR
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Print version and exit.
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.SH "THE LOOP DEVICE"
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The
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.B umount
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command will free the loop device (if any) associated with the mount, in
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case it finds the option 'loop=...' in
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.IR /etc/mtab ,
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or when the \-d option was given. Any pending loop devices can be freed
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using 'losetup -d', see
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.BR losetup (8).
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.SH NOTES
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The syntax of external umount helpers is:
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.PP
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.BI /sbin/umount. <suffix>
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.RI { dir | device }
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.RB [ \-nlfvr ]
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.RB [ \-t
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.IR type.subtype ]
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.PP
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where the <suffix> is filesystem type or a value from "uhelper=" or
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"helper=" mtab option. The \-t option is used for filesystems with
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subtypes support (for example /sbin/mount.fuse -t fuse.sshfs).
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.PP
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The uhelper= (unprivileged umount helper) is possible to use when
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non-root user wants to umount a mountpoint which is not defined in the
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/etc/fstab file (e.g. devices mounted by udisk).
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.PP
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The helper= mount option redirects all umount requests to the
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/sbin/umount.<helper> independently on UID.
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.SH FILES
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.I /etc/mtab
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table of mounted file systems
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.SH ENVIRONMENT
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.IP LIBMOUNT_FSTAB=<path>
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overrides the default location of the fstab file
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.IP LIBMOUNT_MTAB=<path>
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overrides the default location of the mtab file
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.IP LIBMOUNT_DEBUG=0xffff
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enables debug output
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.SH "SEE ALSO"
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.BR umount (2),
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.BR mount (8),
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.BR losetup (8)
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.SH HISTORY
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A
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.B umount
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command appeared in Version 6 AT&T UNIX.
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.SH AVAILABILITY
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The umount command is part of the util-linux package and is available from
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.UR ftp://\:ftp.kernel.org\:/pub\:/linux\:/utils\:/util-linux/
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Linux Kernel Archive
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.UE .
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