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32 .\" @(#)mount.8 8.8 (Berkeley) 6/16/94
33 .\" $FreeBSD: src/sbin/mount/mount.8,v 1.31.2.12 2003/02/23 21:17:42 trhodes Exp $
40 .Nd mount file systems
44 .Op Fl t Ar ufs | external_type
51 .Op Fl t Ar ufs | external_type
58 system call to prepare and graft a
60 or the remote node (rhost:path) on to the file system tree at the point
66 are not provided, the appropriate information is taken from the
70 The system maintains a list of currently mounted file systems.
71 If no arguments are given to
75 The options are as follows:
76 .Bl -tag -width indent
78 All the filesystems described in
81 Exceptions are those marked as
85 flag (see below), or if they are already mounted (except the
86 root filesystem which is always remounted to preserve
87 traditional single user mode behavior).
89 Causes everything to be done except for the actual system call.
90 This option is useful in conjunction with the
95 command is trying to do.
97 Forces the revocation of write access when trying to downgrade
98 a filesystem mount status from read-write to read-only.
100 forces the R/W mount of an unclean filesystem (dangerous; use with
103 Options are specified with a
105 flag followed by a comma separated string of options.
106 In case of conflicting options being specified, the rightmost option
108 The following options are available:
109 .Bl -tag -width indent
113 to the file system should be done asynchronously.
117 and should not be used unless you are prepared to recreate the file
118 system should your system crash.
122 flag, this is the same as specifying the options currently in effect for
123 the mounted filesystem.
127 forces the revocation of write access when trying to downgrade
128 a filesystem mount status from read-write to read-only.
130 forces the R/W mount of an unclean filesystem (dangerous; use with caution).
134 flag, this is the same as specifying all the options listed in the
136 file for the filesystem.
138 Metadata I/O should be done synchronously, while data I/O should be done
142 Do not update the file access time when reading from a file.
144 is useful on filesystems where there are large numbers of files and
145 performance is more critical than updating the file access time (which is
146 rarely ever important).
147 This option is currently only supported on local filesystems.
149 This filesystem should be skipped when
155 Disable read clustering.
157 Disable write clustering.
159 Do not interpret character or block special devices on the file system.
160 This option is useful for a server that has file systems containing
161 special devices for architectures other than its own.
162 This option is set automatically when the user does not have super-user
165 Do not allow execution of any binaries on the mounted file system.
166 This option is useful for a server that has file systems containing
167 binaries for architectures other than its own.
169 Do not allow set-user-identifier or set-group-identifier bits to take effect.
170 Note: this option is worthless if a public available suid or sgid
173 is installed on your system.
174 It is set automatically when the user does not have super-user privileges.
176 Do not follow symlinks
177 on the mounted file system.
181 mount the file system read-only (even the super-user may not write it).
185 to the file system should be done synchronously.
187 A directory on the mounted filesystem will respond to the SUID bit
188 being set, by setting the owner of any new files to be the same
189 as the owner of the directory.
190 New directories will inherit the bit from their parents.
191 Execute bits are removed from
192 the file, and it will not be given to root.
194 This feature is designed for use on fileservers serving PC users via
195 ftp, SAMBA, or netatalk.
196 It provides security holes for shell users and as
197 such should not be used on shell machines, especially on home directories.
198 This option requires the SUIDDIR
199 option in the kernel to work.
200 Only UFS filesystems support this option.
203 for more information.
207 indicate that the status of an already mounted file system should be changed.
209 Causes the namespace at the mount point to appear as the union
210 of the mounted filesystem root and the existing directory.
211 Lookups will be done in the mounted filesystem first.
212 If those operations fail due to a non-existent file the underlying
213 directory is then accessed.
214 All creates are done in the mounted filesystem.
217 Any additional options specific to a filesystem type that is not
218 one of the internally known types (see the
220 option) may be passed as a comma separated list; these options are
221 distinguished by a leading
224 Options that take a value are specified using the syntax -option=value.
228 .Bd -literal -offset indent
229 mount -t mfs -o nosuid,-N,-s=4000 /dev/dk0b /tmp
234 to execute the equivalent of:
235 .Bd -literal -offset indent
236 /sbin/mount_mfs -o nosuid -N -s 4000 /dev/dk0b /tmp
239 Additional options specific to filesystem types
240 which are not internally known
241 (see the description of the
244 may be described in the manual pages for the associated
245 .Pa /sbin/mount_ Ns Sy XXX
248 Print mount information in
255 The file system is to be mounted read-only.
256 Mount the file system read-only (even the super-user may not write it).
262 .It Fl t Ar ufs | external_type
263 The argument following the
265 is used to indicate the file system type.
272 to indicate that the actions should only be taken on
273 filesystems of the specified type.
274 More than one type may be specified in a comma separated list.
275 The list of filesystem types can be prefixed with
277 to specify the filesystem types for which action should
283 .Bd -literal -offset indent
284 mount -a -t nonfs,mfs
287 mounts all filesystems except those of type
292 If the type is not one of the internally known types,
294 will attempt to execute a program in
295 .Pa /sbin/mount_ Ns Sy XXX
298 is replaced by the type name.
299 For example, nfs filesystems are mounted by the program
300 .Pa /sbin/mount_nfs .
302 Most filesystems will be dynamically loaded by their
305 if not already present in the kernel, using the
308 Because this mechanism requires writable temporary space,
309 the filesystem type containing
311 must be compiled into the kernel, and the filesystems containing
317 before any filesystems which might be dynamically loaded.
321 flag indicates that the status of an already mounted file
322 system should be changed.
323 Any of the options discussed above (the
327 also a file system can be changed from read-only to read-write
329 An attempt to change from read-write to read-only will fail if any
330 files on the filesystem are currently open for writing unless the
332 flag is also specified.
333 The set of options is determined by applying the options specified
336 and finally applying the
344 The file system object is to be read and write.
347 Various, most of them are self-explanatory.
349 .Dl XXXXX filesystem is not available
351 The kernel does not support the respective filesystem type.
353 support for a particular filesystem might be provided either on a static
354 (kernel compile-time), or dynamic basis (loaded as a kernel module by
358 or its subprocesses attempt to dynamically load a filesystem module if
359 it has not been configured statically, using
361 In this case, the above error message can also mean that you did not
362 have permission to load the module.
364 .Bl -tag -width /etc/fstab -compact
376 .Xr mount_linprocfs 8 ,
392 It is possible for a corrupted file system to cause a crash.
396 the permissions on the original mount point determine if
398 is accessible from the mounted file system.
399 The minimum permissions for
400 the mount point for traversal across the mount point in both
401 directions to be possible for all users is 0111 (execute for all).