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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 If the device supports trim (kern.cam.da.X.trim_enabled exists) and is set,
198 the file system will perform online trim for corresponding block deletions.
199 Currently UFS only supports this feature.
201 A directory on the mounted filesystem will respond to the SUID bit
202 being set, by setting the owner of any new files to be the same
203 as the owner of the directory.
204 New directories will inherit the bit from their parents.
205 Execute bits are removed from
206 the file, and it will not be given to root.
208 This feature is designed for use on fileservers serving PC users via
209 ftp, SAMBA, or netatalk.
210 It provides security holes for shell users and as
211 such should not be used on shell machines, especially on home directories.
212 This option requires the SUIDDIR
213 option in the kernel to work.
216 filesystems support this option.
219 for more information.
223 indicate that the status of an already mounted file system should be changed.
225 Causes the namespace at the mount point to appear as the union
226 of the mounted filesystem root and the existing directory.
227 Lookups will be done in the mounted filesystem first.
228 If those operations fail due to a non-existent file the underlying
229 directory is then accessed.
230 All creates are done in the mounted filesystem.
236 Any additional options specific to a filesystem type that is not
237 one of the internally known types (see the
239 option) may be passed as a comma separated list; these options are
240 distinguished by a leading
243 Options that take a value are specified using the syntax -option=value.
247 .Bd -literal -offset indent
248 mount -t mfs -o nosuid,-N,-s=4000 /dev/da0s0b /tmp
253 to execute the equivalent of:
254 .Bd -literal -offset indent
255 /sbin/mount_mfs -o nosuid -N -s 4000 /dev/da0s0b /tmp
258 Additional options specific to filesystem types
259 which are not internally known
260 (see the description of the
263 may be described in the manual pages for the associated
264 .Pa /sbin/mount_ Ns Sy XXX
267 Print mount information in
270 If fstab is missing or if the freq and passno fields are omitted,
271 the default values as described in
278 The file system is to be mounted read-only.
279 Mount the file system read-only (even the super-user may not write it).
286 The argument following the
288 is used to indicate the file system type.
295 to indicate that the actions should only be taken on
296 filesystems of the specified type.
297 More than one type may be specified in a comma separated list.
298 The list of filesystem types can be prefixed with
300 to specify the filesystem types for which action should
306 .Bd -literal -offset indent
307 mount -a -t nonfs,mfs
310 mounts all filesystems except those of type
315 If the type is not the internally known type,
318 will attempt to execute a program in
319 .Pa /sbin/mount_ Ns Sy XXX
322 is replaced by the type name.
323 For example, nfs filesystems are mounted by the program
324 .Pa /sbin/mount_nfs .
326 Most filesystems will be dynamically loaded by their
329 if not already present in the kernel, using the
332 Because this mechanism requires writable temporary space,
333 the filesystem type containing
335 must be compiled into the kernel, and the filesystems containing
341 before any filesystems which might be dynamically loaded.
345 flag indicates that the status of an already mounted file
346 system should be changed.
347 Any of the options discussed above (the
351 also a file system can be changed from read-only to read-write
353 An attempt to change from read-write to read-only will fail if any
354 files on the filesystem are currently open for writing unless the
356 flag is also specified.
357 The set of options is determined by applying the options specified
360 and finally applying the
368 The file system object is to be read and write.
371 .Bl -tag -width PATH_FSTAB
373 If the environment variable
375 is set all operations are performed against the specified file.
378 .Bl -tag -width /etc/fstab -compact
383 Various, most of them are self-explanatory.
385 .Dl XXXXX filesystem is not available
387 The kernel does not support the respective filesystem type.
389 support for a particular filesystem might be provided either on a static
390 (kernel compile-time), or dynamic basis (loaded as a kernel module by
394 or its subprocesses attempt to dynamically load a filesystem module if
395 it has not been configured statically, using
397 In this case, the above error message can also mean that you did not
398 have permission to load the module.
414 .Xr mount_linprocfs 8 ,
433 the permissions on the original mount point determine if
435 is accessible from the mounted file system.
436 The minimum permissions for
437 the mount point for traversal across the mount point in both
438 directions to be possible for all users is 0111 (execute for all).
445 It is possible for a corrupted file system to cause a crash.