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UMOUNT

Section: Linux Programmer's Manual (8)
Updated: 26 July 1997
Index 

NAME

umount - unmount file systems 

SYNOPSIS

umount [-hV]

umount -a [-dflnrv] [-t vfstype] [-O options]
umount [-dflnrv] dir | device [...] 

DESCRIPTION

Theumountcommand detaches the file system(s) mentioned from the file hierarchy.A file system is specified by giving the directory where ithas been mounted. Giving the special device on which the file system livesmay also work, but is obsolete, mainly because it will failin case this device was mounted on more than one directory.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 processhas its working directory there, or when a swap file on it is in use.The offending process could even beumountitself - it opens libc, and libc in its turn may open for examplelocale files.A lazy unmount avoids this problem.

Options for theumountcommand:

-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, alsofree this loop device.

-a

All of the file systems described in/etc/mtabare unmounted. (Withumountversion 2.7 and later: theprocfilesystem is not unmounted.)

-t vfstype

Indicate that the actions should only be taken on file systems of thespecified type. More than one type may be specified in a comma separatedlist. The list of file system types can be prefixed withnoto 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 withthe specified options in/etc/fstab.More than one option type may be specified in a comma separatedlist. Each option can be prefixed withnoto specify options for which no action should be taken.

-f

Force unmount. This allows an NFS-mounted filesystem to beunmounted if the NFS server is unreachable. Note: when using umount -f on an NFS filesystem, the filesystem must be mounted using either the soft, or intr options (see nfs(5).This option will not force unmount a `busy' filesystem (use -l instead).(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 busyanymore. This option allows a `busy' filesystem to be unmounted.(Requires kernel 2.4.11 or later.)

 

THE LOOP DEVICE

Theumountcommand will free the loop device (if any) associatedwith 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', seelosetup(8).

 

FILES

/etc/mtabtable of mounted file systems

 

SEE ALSO

umount(2),mount(8),losetup(8).

 

HISTORY

Aumountcommand appeared in Version 6 AT&T UNIX.

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Index

NAME

SYNOPSIS

DESCRIPTION

THE LOOP DEVICE

FILES

SEE ALSO

HISTORY

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