1UMOUNT(8) Linux Programmer's Manual UMOUNT(8)
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6 umount - unmount file systems
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9 umount [-hV]
10 umount -a [-dflnrv] [-t vfstype] [-O options]
12 umount [-dflnrv] {dir|device}...
13
15 The umount command detaches the file system(s) mentioned from the file
16 hierarchy. A file system is specified by giving the directory where it
17 has been mounted. Giving the special device on which the file system
18 lives may also work, but is obsolete, mainly because it will fail in
19 case this device was mounted on more than one directory.
20 Note that a file system cannot be unmounted when it is `busy' - for
22 example, when there are open files on it, or when some process has its
23 working directory there, or when a swap file on it is in use. The
24 offending process could even be umount itself - it opens libc, and libc
25 in its turn may open for example locale files. A lazy unmount avoids
26 this problem.
27 Options for the umount command:
29 -V Print version and exit.
31 -h Print help message and exit.
33 -v Verbose mode.
35 -n Unmount without writing in /etc/mtab.
37 -r In case unmounting fails, try to remount read-only.
39 -d In case the unmounted device was a loop device, also free this
41 loop device.
42 -i Don't call the /sbin/umount.<filesystem> helper even if it
44 exists. By default /sbin/umount.<filesystem> helper is called if
45 one exists.
46 -a All of the file systems described in /etc/mtab are unmounted.
48 (With umount version 2.7 and later: the proc filesystem is not
49 unmounted.)
50 -t vfstype
52 Indicate that the actions should only be taken on file systems
53 of the specified type. More than one type may be specified in a
54 comma separated list. The list of file system types can be pre‐
55 fixed with no to specify the file system types on which no
56 action should be taken.
57 -O options
59 Indicate that the actions should only be taken on file systems
60 with the specified options in /etc/fstab. More than one option
61 type may be specified in a comma separated list. Each option
62 can be prefixed with no to specify options for which no action
63 should be taken.
64 -f Force unmount (in case of an unreachable NFS system). (Requires
66 kernel 2.1.116 or later.)
67 -l Lazy unmount. Detach the filesystem from the filesystem hierar‐
69 chy now, and cleanup all references to the filesystem as soon as
70 it is not busy anymore. (Requires kernel 2.4.11 or later.)
71 --no-canonicalize
73 Don't canonicalize paths. For more details about this option see
74 the mount(8) man page.
75 --fake Causes everything to be done except for the actual system call;
77 this ``fakes'' unmounting the filesystem. It can be used to
78 remove entries from /etc/mtab that were unmounted earlier with
79 the -n option.
80
83 The umount command will free the loop device (if any) associated with
84 the mount, in case it finds the option `loop=...' in /etc/mtab, or when
85 the -d option was given. Any pending loop devices can be freed using
86 `losetup -d', see losetup(8).
87
90 The syntax of external umount helpers is:
91 /sbin/umount.<suffix> {dir|device} [-nlfvr]
93 where the <suffix> is filesystem type or a value from "uhelper=" mtab
95 option.
96 The uhelper (unprivileged umount helper) is possible to used when non-
98 root user wants to umount a mountpoint which is not defined in the
99 /etc/fstab file (e.g devices mounted by HAL).
100
103 /etc/mtab table of mounted file systems
104
107 umount(2), mount(8), losetup(8).
108
111 A umount command appeared in Version 6 AT&T UNIX.
112
114 The umount command is part of the util-linux-ng package and is avail‐
115 able from ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/.
116Linux 2.0 26 July 1997 UMOUNT(8)