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28 .\" @(#)umount.8 8.2 (Berkeley) 5/8/95
36 .Nd unmount file systems
40 .Ar special ... | node ... | fsid ...
52 system call to remove a file system from the file system tree.
53 The file system can be specified by its
55 device or remote node (rhost:path), the path to the mount point
57 or by the file system ID
63 The options are as follows:
64 .Bl -tag -width indent
66 All the file systems described in
70 All the currently mounted file systems except
71 the root are unmounted.
77 The file system is forcibly unmounted.
78 Active special devices continue to work,
79 but all other files return errors if further accesses are attempted.
80 The root file system cannot be forcibly unmounted.
81 For NFS, a forced dismount can take up to 1 minute or more to
82 complete against an unresponsive server and may throw away
83 data not yet written to the server for this case.
93 Also, doing a forced dismount of an NFSv3 mount when
95 is running is unsafe and can result in a crash.
97 Only file systems mounted from the specified host will be
99 This option implies the
101 option and, unless otherwise specified with the
103 option, will only unmount
107 Do a forced dismount of an
109 mount point without checking the mount path.
110 This option can only be used with the path to the mount point
112 and the path must be specified exactly as it was at mount time.
113 This option is useful when a process is hung waiting for an unresponsive
115 server while holding a vnode lock on the mounted-on vnode, such that
120 Using this option can result in a loss of file updates that have not been
129 will not unmount an active file system.
130 It will, however, perform a flush.
131 This flag disables this behaviour, preventing the flush
132 if there are any files open.
134 Is used to indicate the actions should only be taken on
135 file systems of the specified type.
136 More than one type may be specified in a comma separated list.
137 The list of file system types can be prefixed with
139 to specify the file system types for which action should
145 .Bd -literal -offset indent
146 umount -a -t nfs,nullfs
149 unmounts all file systems of the type
153 that are listed in the
157 Verbose, additional information is printed out as each file system
161 .Bl -tag -width ".Ev PATH_FSTAB"
163 If the environment variable
165 is set, all operations are performed against the specified file.
167 will not be honored if the process environment or memory address space is
172 for more information.)
175 .Bl -tag -width /etc/fstab -compact