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diff --git a/sys-utils/umount.8 b/sys-utils/umount.8 new file mode 100644 index 0000000..f94d2f4 --- /dev/null +++ b/sys-utils/umount.8 @@ -0,0 +1,267 @@ +.\" 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 "July 2014" "util-linux" "System Administration" +.SH NAME +umount \- unmount file systems +.SH SYNOPSIS +.B umount \-a +.RB [ \-dflnrv ] +.RB [ \-t +.IR fstype ] +.RB [ \-O +.IR option ...] +.sp +.B umount +.RB [ \-dflnrv ] +.RI { directory | device }... +.sp +.B umount +.BR \-h | \-V + +.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 Giving the special device on which the file system lives may +also work, but is obsolete, mainly because it will fail in case this +device was mounted on more than one directory.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, but it may introduce another +issues. See \fB\-\-lazy\fR description below. +.SH OPTIONS +.TP +.BR \-a , " \-\-all" +All of the filesystems described in +.I /proc/self/mountinfo +(or in deprecated /etc/mtab) +are unmounted, except the proc, devfs, devpts, sysfs, rpc_pipefs and nfsd +filesystems. This list of the filesystems may be replaced by \fB\-\-types\fR +umount option. +.TP +.BR \-A , " \-\-all\-targets" +Unmount all mountpoints in the current namespace for the specified filesystem. +The filesystem can be specified by one of the mountpoints or the device name (or +UUID, etc.). When this option is used together with \fB\-\-recursive\fR, then +all nested mounts within the filesystem are recursively unmounted. +This option is only supported on systems where /etc/mtab is a symlink +to /proc/mounts. +.TP +.BR \-c , " \-\-no\-canonicalize" +Do not canonicalize paths. The paths canonicalization is based on +.BR stat (2) +and +.BR readlink (2) +system calls. These system calls may hang in some cases (for example on NFS if +server is not available). The option has to be used with canonical path to the +mount point. + +For more details about this option see the +.BR mount (8) +man page. Note that \fBumount\fR does not pass this option to the +.BI /sbin/umount. type +helpers. +.TP +.BR \-d , " \-\-detach\-loop" +When the unmounted device was a loop device, also free this loop +device. This option is unnecessary for devices initialized by +.BR mount (8), +in this case "autoclear" functionality is enabled by default. +.TP +.B \-\-fake +Causes everything to be done except for the actual system call or umount helper +execution; this 'fakes' unmounting the filesystem. It can be used to remove +entries from the deprecated +.I /etc/mtab +that were unmounted earlier with the +.B \-n +option. +.TP +.BR \-f , " \-\-force" +Force an unmount (in case of an unreachable NFS system). + +Note that this option does not guarantee that umount command does not hang. +It's strongly recommended to use absolute paths without symlinks to avoid +unwanted readlink and stat system calls on unreachable NFS in umount. +.TP +.BR \-i , " \-\-internal\-only" +Do not call the \fB/sbin/umount.\fIfilesystem\fR helper even if it exists. +By default such a helper program is called if it exists. +.TP +.BR \-l , " \-\-lazy" +Lazy unmount. Detach the filesystem from the file hierarchy now, +and clean up all references to this filesystem as soon as it is not busy +anymore. + +A system reboot would be expected in near future if you're going to use this +option for network filesystem or local filesystem with submounts. The +recommended use-case for \fBumount -l\fR is to prevent hangs on shutdown due to +an unreachable network share where a normal umount will hang due to a downed +server or a network partition. Remounts of the share will not be possible. + +.TP +.BR \-N , " \-\-namespace " \fIns +Perform umount in namespace specified by \fIns\fR. +\fIns\fR is either PID of process running in that namespace +or special file representing that namespace. +.sp +.BR umount (8) +switches to the namespace when it reads /etc/fstab, writes /etc/mtab (or writes to /run/mount) and calls +.BR umount (2) +system call, otherwise it runs in the original namespace. It means that the target namespace does not have +to contain any libraries or another requirements necessary to execute +.BR umount (2) +command. +.sp +See \fBnamespaces\fR(7) for more information. +.TP +.BR \-n , " \-\-no\-mtab" +Unmount without writing in +.IR /etc/mtab . +.TP +.BR \-O , " \-\-test\-opts " \fIoption\fR... +Unmount only the filesystems that have the specified option set 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 indicate that no action should be taken for this option. +.TP +.BR \-q , " \-\-quiet" +Suppress "not mounted" error messages. +.TP +.BR \-R , " \-\-recursive" +Recursively unmount each specified directory. 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; a recursive unmount by device name (or UUID) +is unsupported. +.TP +.BR \-r , " \-\-read\-only" +When an unmount fails, try to remount the filesystem read-only. +.TP +.BR \-t , " \-\-types " \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 indicate that no action should be taken for all of the mentioned types. +Note that +.B umount +reads information about mounted filesystems from kernel (/proc/mounts) and +filesystem names may be different than filesystem names used in the /etc/fstab +(e.g. "nfs4" vs. "nfs"). +.TP +.BR \-v , " \-\-verbose" +Verbose mode. +.TP +.BR \-V , " \-\-version" +Display version information and exit. +.TP +.BR \-h , " \-\-help" +Display help text and exit. +.SH "LOOP DEVICE" +The +.B umount +command will automatically detach loop device previously initialized by +.BR mount (8) +command independently of /etc/mtab. + +In this case the device is initialized with "autoclear" flag (see +.BR losetup (8) +output for more details), otherwise it's necessary to use the option \fB \-\-detach\-loop\fR +or call \fBlosetup -d <device>\fR. The autoclear feature is supported since Linux 2.6.25. +.SH EXTERNAL HELPERS +The syntax of external unmount helpers is: +.PP +.RS +.BI umount. suffix +.RI { directory | device } +.RB [ \-flnrv ] +.RB [ \-N +.IR namespace ] +.RB [ \-t +.IR type . subtype ] +.RE +.PP +where \fIsuffix\fR is the filesystem type (or the value from a +\fBuhelper=\fR or \fBhelper=\fR marker in the mtab file). +The \fB\-t\fR option can be used for filesystems that +have subtype support. For example: +.PP +.RS +.B umount.fuse \-t fuse.sshfs +.RE +.PP +A \fBuhelper=\fIsomething\fR marker (unprivileged helper) can appear in +the \fI/etc/mtab\fR file when ordinary users need to be able to unmount +a mountpoint that is not defined in \fI/etc/fstab\fR +(for example for a device that was mounted by \fBudisks\fR(1)). +.PP +A \fBhelper=\fItype\fR marker in the mtab file will redirect +all unmount requests +to the \fB/sbin/umount.\fItype\fR helper independently of UID. +.PP +Note that \fI/etc/mtab\fR is currently deprecated and helper= and another +userspace mount options are maintained by libmount. +.SH FILES +.TP +.I /etc/mtab +table of mounted filesystems (deprecated and usually replaced by +symlink to /proc/mounts) +.TP +.I /etc/fstab +table of known filesystems +.TP +.I /proc/self/mountinfo +table of mounted filesystems generated by kernel. +.SH ENVIRONMENT +.IP LIBMOUNT_FSTAB=<path> +overrides the default location of the fstab file (ignored for suid) +.IP LIBMOUNT_MTAB=<path> +overrides the default location of the mtab file (ignored for suid) +.IP LIBMOUNT_DEBUG=all +enables libmount debug output +.SH "SEE ALSO" +.BR umount (2), +.BR losetup (8), +.BR mount (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 https://\:www.kernel.org\:/pub\:/linux\:/utils\:/util-linux/ +Linux Kernel Archive +.UE . |