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| .TH UMOUNT 8 "26 July 1997" "Linux 2.0" "Linux Programmer's Manual" |
| .SH NAME |
| umount \- unmount file systems |
| .SH SYNOPSIS |
| .B umount |
| .RB [ \-hV ] |
| .LP |
| .B umount \-a |
| .RB [ \-dflnrv ] |
| .RB [ \-t |
| .IR vfstype ] |
| .RB [ \-O |
| .IR options ] |
| .br |
| .B umount |
| .RB [ \-dflnrv ] |
| .RI { dir | device }... |
| .SH DESCRIPTION |
| The |
| .B 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| may also work, but is obsolete, mainly because it will fail |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 |
| .B 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 |
| .B umount |
| command: |
| .TP |
| .B \-V |
| Print version and exit. |
| .TP |
| .B \-h |
| Print help message and exit. |
| .TP |
| .B \-v |
| Verbose mode. |
| .TP |
| .B \-n |
| Unmount without writing in |
| .IR /etc/mtab . |
| .TP |
| .B \-r |
| In case unmounting fails, try to remount read-only. |
| .TP |
| .B \-d |
| In case the unmounted device was a loop device, also |
| free this loop device. |
| .TP |
| .B \-i |
| Don't call the /sbin/umount.<filesystem> helper even if it exists. By default /sbin/umount.<filesystem> helper is called if one exists. |
| .TP |
| .B \-a |
| All of the file systems described in |
| .I /etc/mtab |
| are unmounted. (With |
| .B umount |
| version 2.7 and later: the |
| .I proc |
| filesystem is not unmounted.) |
| .TP |
| .BI \-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 |
| .B no |
| to specify the file system types on which no action should be taken. |
| .TP |
| .BI \-O " options" |
| Indicate that the actions should only be taken on file systems with |
| the specified options in |
| .IR /etc/fstab . |
| More than one option type 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 |
| .B \-f |
| Force unmount (in case of an unreachable NFS system). |
| (Requires kernel 2.1.116 or later.) |
| .TP |
| .B \-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.) |
| .IP "\fB\-\-no\-canonicalize\fP" |
| Don't canonicalize paths. For more details about this option see the |
| .B mount(8) |
| man page. |
| |
| .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 NOTES |
| The syntax of external umount helpers is: |
| |
| .br |
| .BI /sbin/umount. <suffix> |
| .RI { dir | device } |
| .RB [ \-nlfvr ] |
| .br |
| |
| where the <suffix> is filesystem type or a value from "uhelper=" mtab option. |
| |
| The uhelper (unprivileged umount helper) is possible to used when non-root user |
| wants to umount a mountpoint which is not defined in the /etc/fstab file (e.g |
| devices mounted by HAL). |
| |
| .SH FILES |
| .I /etc/mtab |
| table of mounted file systems |
| |
| .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-ng package and is available from |
| ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/. |