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28 .\" @(#)mount.8 8.8 (Berkeley) 6/16/94
29 .\" $FreeBSD: src/sbin/mount/mount.8,v 1.31.2.12 2003/02/23 21:17:42 trhodes Exp $
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31 .Dd May 15, 2016
32 .Dt MOUNT 8
33 .Os
34 .Sh NAME
35 .Nm mount
36 .Nd mount file systems
37 .Sh SYNOPSIS
38 .Nm
39 .Op Fl adfpruvw
40 .Op Fl F Ar fstab
41 .Op Fl o Ar options
42 .Op Fl t Ar type
43 .Nm
44 .Op Fl dfpruvw
45 .Brq Ar special | node
46 .Nm
47 .Op Fl dfpruvw
48 .Op Fl o Ar options
49 .Op Fl t Ar type
50 .Ar special node
51 .Sh DESCRIPTION
52 The
53 .Nm
54 utility calls the
55 .Xr mount 2
56 system call to prepare and graft a
57 .Ar "special device"
58 or the remote node (rhost:path) or a HAMMER2 label (@label) on to the
59 file system tree at the point
60 .Ar node .
61 If either
62 .Ar special
63 or
64 .Ar node
65 are not provided, the appropriate information is taken from the
66 .Xr fstab 5
67 file.
68 .Pp
69 The system maintains a list of currently mounted file systems.
70 If no arguments are given to
71 .Nm ,
72 this list is printed.
73 .Pp
74 The options are as follows:
75 .Bl -tag -width indent
76 .It Fl a
77 All the filesystems described in
78 .Xr fstab 5
79 are mounted.
80 Exceptions are those marked as
81 .Dq noauto ,
82 excluded by the
83 .Fl t
84 flag (see below), or if they are already mounted (except the
85 root filesystem which is always remounted to preserve
86 traditional single user mode behavior).
87 .It Fl d
88 Causes everything to be done except for the actual system call.
89 This option is useful in conjunction with the
90 .Fl v
91 flag to
92 determine what the
93 .Nm
94 command is trying to do.
95 .It Fl F Ar fstab
96 Specify the
97 .Pa fstab
98 file to use.
99 .It Fl f
100 Forces the revocation of write access when trying to downgrade
101 a filesystem mount status from read-write to read-only.
102 Also
103 forces the R/W mount of an unclean filesystem (dangerous; use with
104 caution).
105 .It Fl o
106 Options are specified with a
107 .Fl o
108 flag followed by a comma separated string of options.
109 If a
110 .Dq no
111 prefix is added or removed from a option name, then meaning is negated.
112 In case of conflicting options being specified, the rightmost option
113 takes effect.
114 The following options are available:
115 .Bl -tag -width indent
116 .It Cm async
117 All
118 .Tn I/O
119 to the file system should be done asynchronously.
120 This is a
121 .Em dangerous
122 flag to set,
123 and should not be used unless you are prepared to recreate the file
124 system should your system crash.
125 .It Cm automounted
126 This flag indicates that the file system was mounted by
127 .Xr automountd 8 .
128 Automounted file systems are automatically unmounted by
129 .Xr autounmountd 8 .
130 .It Cm current
131 When used with the
132 .Fl u
133 flag, this is the same as specifying the options currently in effect for
134 the mounted filesystem.
135 .It Cm force
136 The same as
137 .Fl f ;
138 forces the revocation of write access when trying to downgrade
139 a filesystem mount status from read-write to read-only.
140 Also
141 forces the R/W mount of an unclean filesystem (dangerous; use with caution).
142 .It Cm fstab
143 When used with the
144 .Fl u
145 flag, this is the same as specifying all the options listed in the
146 .Xr fstab 5
147 file for the filesystem.
148 .It Cm noasync
149 Metadata I/O should be done synchronously, while data I/O should be done
150 asynchronously.
151 This is the default.
152 .It Cm noatime
153 Do not update the file access time when reading from a file.
154 This option
155 is useful on filesystems where there are large numbers of files and
156 performance is more critical than updating the file access time (which is
157 rarely ever important).
158 This option is currently only supported on local filesystems.
159 .It Cm noauto
160 This filesystem should be skipped when
161 .Nm
162 is run with the
163 .Fl a
164 flag.
165 .It Cm noclusterr
166 Disable read clustering.
167 .It Cm noclusterw
168 Disable write clustering.
169 .It Cm nodev
170 Do not interpret character or block special devices on the file system.
171 This option is useful for a server that has file systems containing
172 special devices for architectures other than its own.
173 This option is set automatically when the user does not have super-user
174 privileges.
175 .It Cm noexec
176 Do not allow execution of any binaries on the mounted file system.
177 This option is useful for a server that has file systems containing
178 binaries for architectures other than its own.
179 .It Cm nosuid
180 Do not allow set-user-identifier or set-group-identifier bits to take effect.
181 Note: this option is worthless if a public available suid or sgid
182 wrapper like
183 .Xr suidperl 1
184 is installed on your system.
185 It is set automatically when the user does not have super-user privileges.
186 .It Cm nosymfollow
187 Do not follow symlinks
188 on the mounted file system.
189 .It Cm rdonly , ro , norw
190 The same as
191 .Fl r ;
192 mount the file system read-only (even the super-user may not write it).
193 .It Cm sync
194 All
195 .Tn I/O
196 to the file system should be done synchronously.
197 .It Cm trim
198 If the device supports TRIM
199 .Va ( kern.cam.da.X.trim_enabled
200 exists) and is set,
201 the file system will perform online trim for corresponding block deletions.
202 Currently, only
203 .Xr UFS 5
204 supports this feature.
205 .It Cm suiddir
206 A directory on the mounted filesystem will respond to the SUID bit
207 being set, by setting the owner of any new files to be the same
208 as the owner of the directory.
209 New directories will inherit the bit from their parents.
210 Execute bits are removed from
211 the file, and it will not be given to root.
212 .Pp
213 This feature is designed for use on fileservers serving PC users via
214 ftp or SAMBA.
215 It provides security holes for shell users and as
216 such should not be used on shell machines, especially on home directories.
217 This option requires the SUIDDIR
218 option in the kernel to work.
219 Only
220 .Xr UFS 5
221 filesystems support this option.
222 See
223 .Xr chmod 2
224 for more information.
225 .It Cm update
226 The same as
227 .Fl u ;
228 indicate that the status of an already mounted file system should be changed.
229 .It Cm ignore
230 Will be ignored by
231 .Xr df 1 .
232 .El
233 .Pp
234 Any additional options specific to a filesystem type that is not
235 one of the internally known types (see the
236 .Fl t
237 option) may be passed as a comma separated list; these options are
238 distinguished by a leading
239 .Dq \&-
240 (dash).
241 Options that take a value are specified using the syntax -option=value.
242 For example, the
243 .Nm
244 command:
245 .Bd -literal -offset indent
246 mount -t mfs -o nosuid,-N,-s=4000 /dev/da0s0b /tmp
247 .Ed
248 .Pp
249 causes
250 .Nm
251 to execute the equivalent of:
252 .Bd -literal -offset indent
253 /sbin/mount_mfs -o nosuid -N -s 4000 /dev/da0s0b /tmp
254 .Ed
255 .Pp
256 Additional options specific to filesystem types
257 which are not internally known
258 (see the description of the
259 .Fl t
260 option below)
261 may be described in the manual pages for the associated
262 .Pa /sbin/mount_ Ns Sy XXX
263 utilities.
264 .It Fl p
265 Print mount information in
266 .Xr fstab 5
267 format.
268 If fstab is missing or if the freq and passno fields are omitted,
269 the default values as described in
270 .Xr fstab 5
271 are used.
272 Implies also the
273 .Fl v
274 option.
275 .It Fl r
276 The file system is to be mounted read-only.
277 Mount the file system read-only (even the super-user may not write it).
278 The same as the
279 .Cm rdonly
280 argument to the
281 .Fl o
282 option.
283 .It Fl t Ar type
284 The argument following the
285 .Fl t
286 is used to indicate the file system type.
287 The type
288 .Cm ufs
289 is the default.
290 The
291 .Fl t
292 option can be used
293 to indicate that the actions should only be taken on
294 filesystems of the specified type.
295 More than one type may be specified in a comma separated list.
296 The list of filesystem types can be prefixed with
297 .Dq no
298 to specify the filesystem types for which action should
299 .Em not
300 be taken.
301 For example, the
302 .Nm
303 command:
304 .Bd -literal -offset indent
305 mount -a -t nonfs,mfs
306 .Ed
307 .Pp
308 mounts all filesystems except those of type
309 .Tn NFS
310 and
311 .Tn MFS .
312 .Pp
313 If the type is not the internally known type,
314 .Cm ufs ,
315 .Nm
316 will attempt to execute a program in
317 .Pa /sbin/mount_ Ns Sy XXX
318 where
319 .Sy XXX
320 is replaced by the type name.
321 For example, nfs filesystems are mounted by the program
322 .Pa /sbin/mount_nfs .
323 .Pp
324 Most filesystems will be dynamically loaded by their
325 .Nm
326 programs
327 if not already present in the kernel, using the
328 .Xr vfsload 3
329 subroutine.
330 Because this mechanism requires writable temporary space,
331 the filesystem type containing
332 .Pa /tmp
333 must be compiled into the kernel, and the filesystems containing
334 .Pa /tmp
335 and
336 .Pa /usr/bin/ld
337 must be listed in
338 .Pa /etc/fstab
339 before any filesystems which might be dynamically loaded.
340 .It Fl u
341 The
342 .Fl u
343 flag indicates that the status of an already mounted file
344 system should be changed.
345 Any of the options discussed above (the
346 .Fl o
347 option)
348 may be changed;
349 also a file system can be changed from read-only to read-write
350 or vice versa.
351 An attempt to change from read-write to read-only will fail if any
352 files on the filesystem are currently open for writing unless the
353 .Fl f
354 flag is also specified.
355 The set of options is determined by applying the options specified
356 in the argument to
357 .Fl o
358 and finally applying the
359 .Fl r
360 or
361 .Fl w
362 option.
363 .It Fl v
364 Verbose mode.
365 .It Fl w
366 The file system object is to be read and write.
367 .El
368 .Sh ENVIRONMENT
369 .Bl -tag -width PATH_FSTAB
370 .It Pa PATH_FSTAB
371 If the environment variable
372 .Pa PATH_FSTAB
373 is set all operations are performed against the specified file.
374 .El
375 .Sh FILES
376 .Bl -tag -width /etc/fstab -compact
377 .It Pa /etc/fstab
378 file system table
379 .El
380 .Sh DIAGNOSTICS
381 Various, most of them are self-explanatory.
382 .Pp
383 .Dl XXXXX filesystem is not available
384 .Pp
385 The kernel does not support the respective filesystem type.
386 Note that
387 support for a particular filesystem might be provided either on a static
388 (kernel compile-time), or dynamic basis (loaded as a kernel module by
389 .Xr kldload 8 ) .
390 Normally,
391 .Nm
392 or its subprocesses attempt to dynamically load a filesystem module if
393 it has not been configured statically, using
394 .Xr vfsload 3 .
395 In this case, the above error message can also mean that you did not
396 have permission to load the module.
397 .Sh SEE ALSO
398 .Xr df 1 ,
399 .Xr lsvfs 1 ,
400 .Xr mount 2 ,
401 .Xr vfsload 3 ,
402 .Xr devtab 5 ,
403 .Xr fstab 5 ,
404 .Xr UFS 5 ,
405 .Xr automount 8 ,
406 .Xr automountd 8 ,
407 .Xr autounmountd 8 ,
408 .Xr kldload 8 ,
409 .Xr mount_cd9660 8 ,
410 .Xr mount_devfs 8 ,
411 .Xr mount_ext2fs 8 ,
412 .Xr mount_hammer 8 ,
413 .Xr mount_hammer2 8 ,
414 .Xr mount_hpfs 8 ,
415 .Xr mount_mfs 8 ,
416 .Xr mount_msdos 8 ,
417 .Xr mount_nfs 8 ,
418 .Xr mount_ntfs 8 ,
419 .Xr mount_null 8 ,
420 .Xr mount_procfs 8 ,
421 .Xr mount_smbfs 8 ,
422 .Xr mount_std 8 ,
423 .Xr mount_tmpfs 8 ,
424 .Xr mount_udf 8 ,
425 .Xr sysctl 8 ,
426 .Xr umount 8
427 .Sh HISTORY
428 A
429 .Nm
430 utility appeared in
431 .At v1 .
432 .Sh CAVEATS
433 After a successful
434 .Nm ,
435 the permissions on the original mount point determine if
436 .Pa ..\&
437 is accessible from the mounted file system.
438 The minimum permissions for
439 the mount point for traversal across the mount point in both
440 directions to be possible for all users is 0111 (execute for all).
441 .Sh BUGS
442 It is possible for a corrupted file system to cause a crash.