NAME 名字
umount - 卸载文件系统
总览
umount [-hV]
umount -a [-nrv] [-t vfstype]
umount [-nrv] device | dir [...]
描述
umount 可以卸除当前挂载在文件层次目录中的文件系统。文件系统形式可以是以它所在的目录的形式指定，也可以是以它所在的特殊设备的形式来指定。
请注意当文件系统正处于使用状态时，不能进行卸载操作，必须等工作完成后才能进行卸除。例如，如果在当前文件系统中有打开的文件或某些进程正工作在该文件系统的某个目录下时，或者是它上面的一个交换文件正在使用。干涉的进程甚至可以是 umount 本身 - 它打开 libc，而随后 libc 可能会打开本地文件．
umount 命令的选项：
- -V
- 打印版本信息并退出。
- -h
- 显示帮助信息并退出。
- -v
- 以冗长模式运行。
- -n
- 在卸载后不将相应信息写入 /etc/mtab 文件。
- -r
- 如果卸载失败，试图以只读方式进行重新挂载。
- -a
- 卸载所有在 /etc/mtab 文件中描述的文件系统。（在 umount 版本或以后的版本中，不会卸载 proc 文件系统）
- -t vfstype
- 只卸载指定类型的文件系统。如果要一次指定多个文件系统，可以用逗号分隔。如在指定文件系统前加 no ，则可卸载除些文件系统以外的其它文件系统。
- -f
- 强制卸载（比如不可达的 NFS ）。（此选项须在高于 2.1.116 的版本上使用）
环路设备
如果在 /etc/mtab 文件中存在有 `loop=...' 这样的参数， umount 命令将释放与挂载相关联的环路设备．任何挂起的环路设备可以用 `losetup -d' 命令来释放。参阅 losetup(8)．
相关文件
/etc/mtab 已挂载文件系统的清单。
另见
umount(2), mount(8), losetup(8).
#p#
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 Giving the special device on which the file system lives may also work, but is obsolete, mainly because it will fail in case this device was mounted on more than one directory.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 example locale files. A lazy unmount avoids this problem.
Options for the umount command:
- -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, also free this loop device.
- -a
- All of the file systems described in /etc/mtab are unmounted. (With umount version 2.7 and later: the proc filesystem is not unmounted.)
- -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 no to 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 with the specified options in /etc/fstab. More than one option type may be specified in a comma separated list. Each option can be prefixed with no to specify options for which no action should be taken.
- -f
- Force unmount (in case of an unreachable NFS system). (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 busy anymore. (Requires kernel 2.4.11 or later.)
THE LOOP DEVICE
The umount command will free the loop device (if any) associated with 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', see losetup(8).
FILES
/etc/mtab table of mounted file systems
SEE ALSO
umount(2), mount(8), losetup(8).
