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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 $
34 .\" $DragonFly: src/sbin/mount/mount.8,v 1.8 2008/04/23 21:59:22 thomas Exp $
41 .Nd mount file systems
50 .Brq Ar special | node
61 system call to prepare and graft a
63 or the remote node (rhost:path) on to the file system tree at the point
69 are not provided, the appropriate information is taken from the
73 The system maintains a list of currently mounted file systems.
74 If no arguments are given to
78 The options are as follows:
79 .Bl -tag -width indent
81 All the filesystems described in
84 Exceptions are those marked as
88 flag (see below), or if they are already mounted (except the
89 root filesystem which is always remounted to preserve
90 traditional single user mode behavior).
92 Causes everything to be done except for the actual system call.
93 This option is useful in conjunction with the
98 command is trying to do.
104 Forces the revocation of write access when trying to downgrade
105 a filesystem mount status from read-write to read-only.
107 forces the R/W mount of an unclean filesystem (dangerous; use with
110 Options are specified with a
112 flag followed by a comma separated string of options.
115 prefix is added or removed from a option name, then meaning is negated.
116 In case of conflicting options being specified, the rightmost option
118 The following options are available:
119 .Bl -tag -width indent
123 to the file system should be done asynchronously.
127 and should not be used unless you are prepared to recreate the file
128 system should your system crash.
132 flag, this is the same as specifying the options currently in effect for
133 the mounted filesystem.
137 forces the revocation of write access when trying to downgrade
138 a filesystem mount status from read-write to read-only.
140 forces the R/W mount of an unclean filesystem (dangerous; use with caution).
144 flag, this is the same as specifying all the options listed in the
146 file for the filesystem.
148 Metadata I/O should be done synchronously, while data I/O should be done
152 Do not update the file access time when reading from a file.
154 is useful on filesystems where there are large numbers of files and
155 performance is more critical than updating the file access time (which is
156 rarely ever important).
157 This option is currently only supported on local filesystems.
159 This filesystem should be skipped when
165 Disable read clustering.
167 Disable write clustering.
169 Do not interpret character or block special devices on the file system.
170 This option is useful for a server that has file systems containing
171 special devices for architectures other than its own.
172 This option is set automatically when the user does not have super-user
175 Do not allow execution of any binaries on the mounted file system.
176 This option is useful for a server that has file systems containing
177 binaries for architectures other than its own.
179 Do not allow set-user-identifier or set-group-identifier bits to take effect.
180 Note: this option is worthless if a public available suid or sgid
183 is installed on your system.
184 It is set automatically when the user does not have super-user privileges.
186 Do not follow symlinks
187 on the mounted file system.
188 .It Cm rdonly , ro , norw
191 mount the file system read-only (even the super-user may not write it).
195 to the file system should be done synchronously.
197 A directory on the mounted filesystem will respond to the SUID bit
198 being set, by setting the owner of any new files to be the same
199 as the owner of the directory.
200 New directories will inherit the bit from their parents.
201 Execute bits are removed from
202 the file, and it will not be given to root.
204 This feature is designed for use on fileservers serving PC users via
205 ftp, SAMBA, or netatalk.
206 It provides security holes for shell users and as
207 such should not be used on shell machines, especially on home directories.
208 This option requires the SUIDDIR
209 option in the kernel to work.
212 filesystems support this option.
215 for more information.
219 indicate that the status of an already mounted file system should be changed.
221 Causes the namespace at the mount point to appear as the union
222 of the mounted filesystem root and the existing directory.
223 Lookups will be done in the mounted filesystem first.
224 If those operations fail due to a non-existent file the underlying
225 directory is then accessed.
226 All creates are done in the mounted filesystem.
232 Any additional options specific to a filesystem type that is not
233 one of the internally known types (see the
235 option) may be passed as a comma separated list; these options are
236 distinguished by a leading
239 Options that take a value are specified using the syntax -option=value.
243 .Bd -literal -offset indent
244 mount -t mfs -o nosuid,-N,-s=4000 /dev/da0s0b /tmp
249 to execute the equivalent of:
250 .Bd -literal -offset indent
251 /sbin/mount_mfs -o nosuid -N -s 4000 /dev/da0s0b /tmp
254 Additional options specific to filesystem types
255 which are not internally known
256 (see the description of the
259 may be described in the manual pages for the associated
260 .Pa /sbin/mount_ Ns Sy XXX
263 Print mount information in
266 If fstab is missing or if the freq and passno fields are omitted,
267 the default values as described in
274 The file system is to be mounted read-only.
275 Mount the file system read-only (even the super-user may not write it).
282 The argument following the
284 is used to indicate the file system type.
291 to indicate that the actions should only be taken on
292 filesystems of the specified type.
293 More than one type may be specified in a comma separated list.
294 The list of filesystem types can be prefixed with
296 to specify the filesystem types for which action should
302 .Bd -literal -offset indent
303 mount -a -t nonfs,mfs
306 mounts all filesystems except those of type
311 If the type is not the internally known type,
314 will attempt to execute a program in
315 .Pa /sbin/mount_ Ns Sy XXX
318 is replaced by the type name.
319 For example, nfs filesystems are mounted by the program
320 .Pa /sbin/mount_nfs .
322 Most filesystems will be dynamically loaded by their
325 if not already present in the kernel, using the
328 Because this mechanism requires writable temporary space,
329 the filesystem type containing
331 must be compiled into the kernel, and the filesystems containing
337 before any filesystems which might be dynamically loaded.
341 flag indicates that the status of an already mounted file
342 system should be changed.
343 Any of the options discussed above (the
347 also a file system can be changed from read-only to read-write
349 An attempt to change from read-write to read-only will fail if any
350 files on the filesystem are currently open for writing unless the
352 flag is also specified.
353 The set of options is determined by applying the options specified
356 and finally applying the
364 The file system object is to be read and write.
367 .Bl -tag -width PATH_FSTAB
369 If the environment variable
371 is set all operations are performed against the specified file.
374 .Bl -tag -width /etc/fstab -compact
379 Various, most of them are self-explanatory.
381 .Dl XXXXX filesystem is not available
383 The kernel does not support the respective filesystem type.
385 support for a particular filesystem might be provided either on a static
386 (kernel compile-time), or dynamic basis (loaded as a kernel module by
390 or its subprocesses attempt to dynamically load a filesystem module if
391 it has not been configured statically, using
393 In this case, the above error message can also mean that you did not
394 have permission to load the module.
410 .Xr mount_linprocfs 8 ,
429 the permissions on the original mount point determine if
431 is accessible from the mounted file system.
432 The minimum permissions for
433 the mount point for traversal across the mount point in both
434 directions to be possible for all users is 0111 (execute for all).
441 It is possible for a corrupted file system to cause a crash.