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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
56 .Pq Ar rhost Ns Cm \& : Ns Ar path ,
57 the path to the mount point
59 or by the file system ID
65 The options are as follows:
66 .Bl -tag -width "-F fstab"
68 All the file systems described in
72 All the currently mounted file systems are unmounted,
73 except for those mounted at
82 The file system is forcibly unmounted.
83 Active special devices continue to work,
84 but all other files return errors if further accesses are attempted.
85 The root file system cannot be forcibly unmounted.
86 For NFS, a forced dismount can take up to 1 minute or more to
87 complete against an unresponsive server and may throw away
88 data not yet written to the server for this case.
98 Also, doing a forced dismount of an NFSv3 mount when
100 is running is unsafe and can result in a crash.
102 Only file systems mounted from the specified host will be
104 This option implies the
106 option and, unless otherwise specified with the
108 option, will only unmount
112 Do a forced dismount of an
114 mount point without checking the mount path.
115 This option can only be used with the path to the mount point
117 and the path must be specified exactly as it was at mount time.
118 This option is useful when a process is hung waiting for an unresponsive
120 server while holding a vnode lock on the mounted-on vnode, such that
125 Using this option can result in a loss of file updates that have not been
134 will not unmount an active file system.
135 It will, however, perform a flush.
136 This flag disables this behaviour, preventing the flush
137 if there are any files open.
139 Is used to indicate the actions should only be taken on
140 file systems of the specified type.
141 More than one type may be specified in a comma separated list.
142 The list of file system types can be prefixed with
144 to specify the file system types for which action should
150 .Bd -literal -offset indent
151 umount -a -t nfs,nullfs
154 unmounts all file systems of the type
158 that are listed in the
162 Verbose, additional information is printed out as each file system
166 .Bl -tag -width ".Ev PATH_FSTAB"
168 If the environment variable
170 is set, all operations are performed against the specified file.
172 will not be honored if the process environment or memory address space is
177 for more information.)
180 .Bl -tag -width /etc/fstab -compact