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28 .\" @(#)umount.8 8.2 (Berkeley) 5/8/95
35 .Nd unmount file systems
39 .Ar special ... | node ... | fsid ...
51 system call to remove a file system from the file system tree.
52 The file system can be specified by its
55 .Pq Ar rhost Ns Cm \& : Ns Ar path ,
56 the path to the mount point
58 or by the file system ID
64 The options are as follows:
65 .Bl -tag -width "-F fstab"
67 All the file systems described in
71 All the currently mounted file systems are unmounted,
72 except for those mounted at
81 The file system is forcibly unmounted.
82 Active special devices continue to work,
83 but all other files return errors if further accesses are attempted.
84 The root file system cannot be forcibly unmounted.
85 For NFS, a forced dismount can take up to 1 minute or more to
86 complete against an unresponsive server and may throw away
87 data not yet written to the server for this case.
97 Also, doing a forced dismount of an NFSv3 mount when
99 is running is unsafe and can result in a crash.
101 Only file systems mounted from the specified host will be
103 This option implies the
105 option and, unless otherwise specified with the
107 option, will only unmount
111 Do a forced dismount of an
113 mount point without checking the mount path.
114 This option can only be used with the path to the mount point
116 and the path must be specified exactly as it was at mount time.
117 This option is useful when a process is hung waiting for an unresponsive
119 server while holding a vnode lock on the mounted-on vnode, such that
124 Using this option can result in a loss of file updates that have not been
133 will not unmount an active file system.
134 It will, however, perform a flush.
135 This flag disables this behaviour, preventing the flush
136 if there are any files open.
138 Is used to indicate the actions should only be taken on
139 file systems of the specified type.
140 More than one type may be specified in a comma separated list.
141 The list of file system types can be prefixed with
143 to specify the file system types for which action should
149 .Bd -literal -offset indent
150 umount -a -t nfs,nullfs
153 unmounts all file systems of the type
157 that are listed in the
161 Verbose, additional information is printed out as each file system
165 .Bl -tag -width ".Ev PATH_FSTAB"
167 If the environment variable
169 is set, all operations are performed against the specified file.
171 will not be honored if the process environment or memory address space is
176 for more information.)
179 .Bl -tag -width /etc/fstab -compact