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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 $
35 .\"
36 .Dd February 3, 2009
37 .Dt MOUNT 8
38 .Os
39 .Sh NAME
40 .Nm mount
41 .Nd mount file systems
42 .Sh SYNOPSIS
43 .Nm
44 .Op Fl adfpruvw
45 .Op Fl o Ar options
46 .Op Fl t Ar ufs | external_type
47 .Nm
48 .Op Fl dfpruvw
49 .Ar special | node
50 .Nm
51 .Op Fl dfpruvw
52 .Op Fl o Ar options
53 .Op Fl t Ar ufs | external_type
54 .Ar special node
55 .Sh DESCRIPTION
56 The
57 .Nm
58 utility calls the
59 .Xr mount 2
60 system call to prepare and graft a
61 .Ar "special device"
62 or the remote node (rhost:path) on to the file system tree at the point
63 .Ar node .
64 If either
65 .Ar special
66 or
67 .Ar node
68 are not provided, the appropriate information is taken from the
69 .Xr fstab 5
70 file.
71 .Pp
72 The system maintains a list of currently mounted file systems.
73 If no arguments are given to
74 .Nm ,
75 this list is printed.
76 .Pp
77 The options are as follows:
78 .Bl -tag -width indent
79 .It Fl a
80 All the filesystems described in
81 .Xr fstab 5
82 are mounted.
83 Exceptions are those marked as
84 .Dq noauto ,
85 excluded by the
86 .Fl t
87 flag (see below), or if they are already mounted (except the
88 root filesystem which is always remounted to preserve
89 traditional single user mode behavior).
90 .It Fl d
91 Causes everything to be done except for the actual system call.
92 This option is useful in conjunction with the
93 .Fl v
94 flag to
95 determine what the
96 .Nm
97 command is trying to do.
98 .It Fl f
99 Forces the revocation of write access when trying to downgrade
100 a filesystem mount status from read-write to read-only.
101 Also
102 forces the R/W mount of an unclean filesystem (dangerous; use with
103 caution).
104 .It Fl o
105 Options are specified with a
106 .Fl o
107 flag followed by a comma separated string of options.
108 In case of conflicting options being specified, the rightmost option
109 takes effect.
110 The following options are available:
111 .Bl -tag -width indent
112 .It Cm async
113 All
114 .Tn I/O
115 to the file system should be done asynchronously.
116 This is a
117 .Em dangerous
118 flag to set,
119 and should not be used unless you are prepared to recreate the file
120 system should your system crash.
121 .It Cm current
122 When used with the
123 .Fl u
124 flag, this is the same as specifying the options currently in effect for
125 the mounted filesystem.
126 .It Cm force
127 The same as
128 .Fl f ;
129 forces the revocation of write access when trying to downgrade
130 a filesystem mount status from read-write to read-only.
131 Also
132 forces the R/W mount of an unclean filesystem (dangerous; use with caution).
133 .It Cm fstab
134 When used with the
135 .Fl u
136 flag, this is the same as specifying all the options listed in the
137 .Xr fstab 5
138 file for the filesystem.
139 .It Cm noasync
140 Metadata I/O should be done synchronously, while data I/O should be done
141 asynchronously.
142 This is the default.
143 .It Cm noatime
144 Do not update the file access time when reading from a file.
145 This option
146 is useful on filesystems where there are large numbers of files and
147 performance is more critical than updating the file access time (which is
148 rarely ever important).
149 This option is currently only supported on local filesystems.
150 .It Cm noauto
151 This filesystem should be skipped when
152 .Nm
153 is run with the
154 .Fl a
155 flag.
156 .It Cm noclusterr
157 Disable read clustering.
158 .It Cm noclusterw
159 Disable write clustering.
160 .It Cm nodev
161 Do not interpret character or block special devices on the file system.
162 This option is useful for a server that has file systems containing
163 special devices for architectures other than its own.
164 This option is set automatically when the user does not have super-user
165 privileges.
166 .It Cm noexec
167 Do not allow execution of any binaries on the mounted file system.
168 This option is useful for a server that has file systems containing
169 binaries for architectures other than its own.
170 .It Cm nosuid
171 Do not allow set-user-identifier or set-group-identifier bits to take effect.
172 Note: this option is worthless if a public available suid or sgid
173 wrapper like
174 .Xr suidperl 1
175 is installed on your system.
176 It is set automatically when the user does not have super-user privileges.
177 .It Cm nosymfollow
178 Do not follow symlinks
179 on the mounted file system.
180 .It Cm rdonly
181 The same as
182 .Fl r ;
183 mount the file system read-only (even the super-user may not write it).
184 .It Cm sync
185 All
186 .Tn I/O
187 to the file system should be done synchronously.
188 .It Cm suiddir
189 A directory on the mounted filesystem will respond to the SUID bit
190 being set, by setting the owner of any new files to be the same
191 as the owner of the directory.
192 New directories will inherit the bit from their parents.
193 Execute bits are removed from
194 the file, and it will not be given to root.
195 .Pp
196 This feature is designed for use on fileservers serving PC users via
197 ftp, SAMBA, or netatalk.
198 It provides security holes for shell users and as
199 such should not be used on shell machines, especially on home directories.
200 This option requires the SUIDDIR
201 option in the kernel to work.
202 Only
203 .Xr UFS 5
204 filesystems support this option.
205 See
206 .Xr chmod 2
207 for more information.
208 .It Cm update
209 The same as
210 .Fl u ;
211 indicate that the status of an already mounted file system should be changed.
212 .It Cm union
213 Causes the namespace at the mount point to appear as the union
214 of the mounted filesystem root and the existing directory.
215 Lookups will be done in the mounted filesystem first.
216 If those operations fail due to a non-existent file the underlying
217 directory is then accessed.
218 All creates are done in the mounted filesystem.
219 .El
220 .Pp
221 Any additional options specific to a filesystem type that is not
222 one of the internally known types (see the
223 .Fl t
224 option) may be passed as a comma separated list; these options are
225 distinguished by a leading
226 .Dq \&-
227 (dash).
228 Options that take a value are specified using the syntax -option=value.
229 For example, the
230 .Nm
231 command:
232 .Bd -literal -offset indent
233 mount -t mfs -o nosuid,-N,-s=4000 /dev/dk0b /tmp
234 .Ed
235 .Pp
236 causes
237 .Nm
238 to execute the equivalent of:
239 .Bd -literal -offset indent
240 /sbin/mount_mfs -o nosuid -N -s 4000 /dev/dk0b /tmp
241 .Ed
242 .Pp
243 Additional options specific to filesystem types
244 which are not internally known
245 (see the description of the
246 .Fl t
247 option below)
248 may be described in the manual pages for the associated
249 .Pa /sbin/mount_ Ns Sy XXX
250 utilities.
251 .It Fl p
252 Print mount information in
253 .Xr fstab 5
254 format.
255 If fstab is missing or if the freq and passno fields are omitted,
256 the default values as described in
257 .Xr fstab 5
258 are used.
259 Implies also the
260 .Fl v
261 option.
262 .It Fl r
263 The file system is to be mounted read-only.
264 Mount the file system read-only (even the super-user may not write it).
265 The same as the
266 .Cm rdonly
267 argument to the
268 .Fl o
269 option.
270 .It Fl t Ar ufs | external_type
271 The argument following the
272 .Fl t
273 is used to indicate the file system type.
274 The type
275 .Ar ufs
276 is the default.
277 The
278 .Fl t
279 option can be used
280 to indicate that the actions should only be taken on
281 filesystems of the specified type.
282 More than one type may be specified in a comma separated list.
283 The list of filesystem types can be prefixed with
284 .Dq no
285 to specify the filesystem types for which action should
286 .Em not
287 be taken.
288 For example, the
289 .Nm
290 command:
291 .Bd -literal -offset indent
292 mount -a -t nonfs,mfs
293 .Ed
294 .Pp
295 mounts all filesystems except those of type
296 .Tn NFS
297 and
298 .Tn MFS .
299 .Pp
300 If the type is not one of the internally known types,
301 .Nm
302 will attempt to execute a program in
303 .Pa /sbin/mount_ Ns Sy XXX
304 where
305 .Sy XXX
306 is replaced by the type name.
307 For example, nfs filesystems are mounted by the program
308 .Pa /sbin/mount_nfs .
309 .Pp
310 Most filesystems will be dynamically loaded by their
311 .Nm
312 programs
313 if not already present in the kernel, using the
314 .Xr vfsload 3
315 subroutine.
316 Because this mechanism requires writable temporary space,
317 the filesystem type containing
318 .Pa /tmp
319 must be compiled into the kernel, and the filesystems containing
320 .Pa /tmp
321 and
322 .Pa /usr/bin/ld
323 must be listed in
324 .Pa /etc/fstab
325 before any filesystems which might be dynamically loaded.
326 .It Fl u
327 The
328 .Fl u
329 flag indicates that the status of an already mounted file
330 system should be changed.
331 Any of the options discussed above (the
332 .Fl o
333 option)
334 may be changed;
335 also a file system can be changed from read-only to read-write
336 or vice versa.
337 An attempt to change from read-write to read-only will fail if any
338 files on the filesystem are currently open for writing unless the
339 .Fl f
340 flag is also specified.
341 The set of options is determined by applying the options specified
342 in the argument to
343 .Fl o
344 and finally applying the
345 .Fl r
346 or
347 .Fl w
348 option.
349 .It Fl v
350 Verbose mode.
351 .It Fl w
352 The file system object is to be read and write.
353 .El
354 .Sh FILES
355 .Bl -tag -width /etc/fstab -compact
356 .It Pa /etc/fstab
357 file system table
358 .El
359 .Sh DIAGNOSTICS
360 Various, most of them are self-explanatory.
361 .Pp
362 .Dl XXXXX filesystem is not available
363 .Pp
364 The kernel does not support the respective filesystem type.
365 Note that
366 support for a particular filesystem might be provided either on a static
367 (kernel compile-time), or dynamic basis (loaded as a kernel module by
368 .Xr kldload 8 ) .
369 Normally,
370 .Nm
371 or its subprocesses attempt to dynamically load a filesystem module if
372 it has not been configured statically, using
373 .Xr vfsload 3 .
374 In this case, the above error message can also mean that you did not
375 have permission to load the module.
376 .Sh SEE ALSO
377 .Xr lsvfs 1 ,
378 .Xr mount 2 ,
379 .Xr vfsload 3 ,
380 .Xr fstab 5 ,
381 .Xr kldload 8 ,
382 .Xr mount_cd9660 8 ,
383 .Xr mount_ext2fs 8 ,
384 .Xr mount_fdesc 8 ,
385 .Xr mount_hammer 8 ,
386 .Xr mount_linprocfs 8 ,
387 .Xr mount_mfs 8 ,
388 .Xr mount_msdos 8 ,
389 .Xr mount_nfs 8 ,
390 .Xr mount_ntfs 8 ,
391 .Xr mount_null 8 ,
392 .Xr mount_nwfs 8 ,
393 .Xr mount_portal 8 ,
394 .Xr mount_procfs 8 ,
395 .Xr mount_smbfs 8 ,
396 .Xr mount_std 8 ,
397 .Xr mount_udf 8 ,
398 .Xr mount_union 8 ,
399 .Xr sysctl 8 ,
400 .Xr umount 8
401 .Sh CAVEATS
402 After a successful
403 .Nm ,
404 the permissions on the original mount point determine if
405 .Pa ..\&
406 is accessible from the mounted file system.
407 The minimum permissions for
408 the mount point for traversal across the mount point in both
409 directions to be possible for all users is 0111 (execute for all).
410 .Sh HISTORY
411 A
412 .Nm
413 utility appeared in
414 .At v1 .
415 .Sh BUGS
416 It is possible for a corrupted file system to cause a crash.