man umount 命令下的文件

UMOUNT(8) System Administration UMOUNT(8)
NAME
umount - unmount file systems
SYNOPSIS
umount [-hV]
umount -a [-dflnrv] [-t vfstype] [-O options]
umount [-dflnrv] {dir|device}…
DESCRIPTION
The 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file system lives may also work, but is obsolete, mainly because it will fail in case this device was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 umount itself - it opens libc, and libc in its turn may open for exam‐
ple locale files. A lazy unmount avoids this problem.
OPTIONS
-a, –all
All of the file systems described in /etc/mtab are unmounted. (With umount version 2.7 and
later: the proc filesystem is not unmounted.)
-A, –all-targets
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 –recursive then all nested mounts within the filesystem are recursively
unmounted.
-c, –no-canonicalize
Do not canonicalize paths. For more details about this option see the mount(8) man page.
-d, –detach-loop
In case the unmounted device was a loop device, also free this loop device.
–fake Causes everything to be done except for the actual system call; this ‘fakes’ unmounting the
filesystem. It can be used to remove entries from /etc/mtab that were unmounted earlier with
the -n option.
-f, –force
Force unmount (in case of an unreachable NFS system). (Requires kernel 2.1.116 or later.)
-i, –internal-only
Do not call the /sbin/umount. helper even if it exists. By default
/sbin/umount. helper is called if one exists.