xref: /dragonfly/sbin/mount/mount.8 (revision 409b4c59)
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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
56The
57.Nm
58utility calls the
59.Xr mount 2
60system call to prepare and graft a
61.Ar "special device"
62or the remote node (rhost:path) on to the file system tree at the point
63.Ar node .
64If either
65.Ar special
66or
67.Ar node
68are not provided, the appropriate information is taken from the
69.Xr fstab 5
70file.
71.Pp
72The system maintains a list of currently mounted file systems.
73If no arguments are given to
74.Nm ,
75this list is printed.
76.Pp
77The options are as follows:
78.Bl -tag -width indent
79.It Fl a
80All the filesystems described in
81.Xr fstab 5
82are mounted.
83Exceptions are those marked as
84.Dq noauto ,
85excluded by the
86.Fl t
87flag (see below), or if they are already mounted (except the
88root filesystem which is always remounted to preserve
89traditional single user mode behavior).
90.It Fl d
91Causes everything to be done except for the actual system call.
92This option is useful in conjunction with the
93.Fl v
94flag to
95determine what the
96.Nm
97command is trying to do.
98.It Fl f
99Forces the revocation of write access when trying to downgrade
100a filesystem mount status from read-write to read-only.
101Also
102forces the R/W mount of an unclean filesystem (dangerous; use with
103caution).
104.It Fl o
105Options are specified with a
106.Fl o
107flag followed by a comma separated string of options.
108In case of conflicting options being specified, the rightmost option
109takes effect.
110The following options are available:
111.Bl -tag -width indent
112.It Cm async
113All
114.Tn I/O
115to the file system should be done asynchronously.
116This is a
117.Em dangerous
118flag to set,
119and should not be used unless you are prepared to recreate the file
120system should your system crash.
121.It Cm current
122When used with the
123.Fl u
124flag, this is the same as specifying the options currently in effect for
125the mounted filesystem.
126.It Cm force
127The same as
128.Fl f ;
129forces the revocation of write access when trying to downgrade
130a filesystem mount status from read-write to read-only.
131Also
132forces the R/W mount of an unclean filesystem (dangerous; use with caution).
133.It Cm fstab
134When used with the
135.Fl u
136flag, this is the same as specifying all the options listed in the
137.Xr fstab 5
138file for the filesystem.
139.It Cm noasync
140Metadata I/O should be done synchronously, while data I/O should be done
141asynchronously.
142This is the default.
143.It Cm noatime
144Do not update the file access time when reading from a file.
145This option
146is useful on filesystems where there are large numbers of files and
147performance is more critical than updating the file access time (which is
148rarely ever important).
149This option is currently only supported on local filesystems.
150.It Cm noauto
151This filesystem should be skipped when
152.Nm
153is run with the
154.Fl a
155flag.
156.It Cm noclusterr
157Disable read clustering.
158.It Cm noclusterw
159Disable write clustering.
160.It Cm nodev
161Do not interpret character or block special devices on the file system.
162This option is useful for a server that has file systems containing
163special devices for architectures other than its own.
164This option is set automatically when the user does not have super-user
165privileges.
166.It Cm noexec
167Do not allow execution of any binaries on the mounted file system.
168This option is useful for a server that has file systems containing
169binaries for architectures other than its own.
170.It Cm nosuid
171Do not allow set-user-identifier or set-group-identifier bits to take effect.
172Note: this option is worthless if a public available suid or sgid
173wrapper like
174.Xr suidperl 1
175is installed on your system.
176It is set automatically when the user does not have super-user privileges.
177.It Cm nosymfollow
178Do not follow symlinks
179on the mounted file system.
180.It Cm rdonly
181The same as
182.Fl r ;
183mount the file system read-only (even the super-user may not write it).
184.It Cm sync
185All
186.Tn I/O
187to the file system should be done synchronously.
188.It Cm suiddir
189A directory on the mounted filesystem will respond to the SUID bit
190being set, by setting the owner of any new files to be the same
191as the owner of the directory.
192New directories will inherit the bit from their parents.
193Execute bits are removed from
194the file, and it will not be given to root.
195.Pp
196This feature is designed for use on fileservers serving PC users via
197ftp, SAMBA, or netatalk.
198It provides security holes for shell users and as
199such should not be used on shell machines, especially on home directories.
200This option requires the SUIDDIR
201option in the kernel to work.
202Only
203.Xr UFS 5
204filesystems support this option.
205See
206.Xr chmod 2
207for more information.
208.It Cm update
209The same as
210.Fl u ;
211indicate that the status of an already mounted file system should be changed.
212.It Cm union
213Causes the namespace at the mount point to appear as the union
214of the mounted filesystem root and the existing directory.
215Lookups will be done in the mounted filesystem first.
216If those operations fail due to a non-existent file the underlying
217directory is then accessed.
218All creates are done in the mounted filesystem.
219.El
220.Pp
221Any additional options specific to a filesystem type that is not
222one of the internally known types (see the
223.Fl t
224option) may be passed as a comma separated list; these options are
225distinguished by a leading
226.Dq \&-
227(dash).
228Options that take a value are specified using the syntax -option=value.
229For example, the
230.Nm
231command:
232.Bd -literal -offset indent
233mount -t mfs -o nosuid,-N,-s=4000 /dev/dk0b /tmp
234.Ed
235.Pp
236causes
237.Nm
238to 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
243Additional options specific to filesystem types
244which are not internally known
245(see the description of the
246.Fl t
247option below)
248may be described in the manual pages for the associated
249.Pa /sbin/mount_ Ns Sy XXX
250utilities.
251.It Fl p
252Print mount information in
253.Xr fstab 5
254format.
255If fstab is missing or if the freq and passno fields are omitted,
256the default values as described in
257.Xr fstab 5
258are used.
259Implies also the
260.Fl v
261option.
262.It Fl r
263The file system is to be mounted read-only.
264Mount the file system read-only (even the super-user may not write it).
265The same as the
266.Cm rdonly
267argument to the
268.Fl o
269option.
270.It Fl t Ar ufs | external_type
271The argument following the
272.Fl t
273is used to indicate the file system type.
274The type
275.Ar ufs
276is the default.
277The
278.Fl t
279option can be used
280to indicate that the actions should only be taken on
281filesystems of the specified type.
282More than one type may be specified in a comma separated list.
283The list of filesystem types can be prefixed with
284.Dq no
285to specify the filesystem types for which action should
286.Em not
287be taken.
288For example, the
289.Nm
290command:
291.Bd -literal -offset indent
292mount -a -t nonfs,mfs
293.Ed
294.Pp
295mounts all filesystems except those of type
296.Tn NFS
297and
298.Tn MFS .
299.Pp
300If the type is not one of the internally known types,
301.Nm
302will attempt to execute a program in
303.Pa /sbin/mount_ Ns Sy XXX
304where
305.Sy XXX
306is replaced by the type name.
307For example, nfs filesystems are mounted by the program
308.Pa /sbin/mount_nfs .
309.Pp
310Most filesystems will be dynamically loaded by their
311.Nm
312programs
313if not already present in the kernel, using the
314.Xr vfsload 3
315subroutine.
316Because this mechanism requires writable temporary space,
317the filesystem type containing
318.Pa /tmp
319must be compiled into the kernel, and the filesystems containing
320.Pa /tmp
321and
322.Pa /usr/bin/ld
323must be listed in
324.Pa /etc/fstab
325before any filesystems which might be dynamically loaded.
326.It Fl u
327The
328.Fl u
329flag indicates that the status of an already mounted file
330system should be changed.
331Any of the options discussed above (the
332.Fl o
333option)
334may be changed;
335also a file system can be changed from read-only to read-write
336or vice versa.
337An attempt to change from read-write to read-only will fail if any
338files on the filesystem are currently open for writing unless the
339.Fl f
340flag is also specified.
341The set of options is determined by applying the options specified
342in the argument to
343.Fl o
344and finally applying the
345.Fl r
346or
347.Fl w
348option.
349.It Fl v
350Verbose mode.
351.It Fl w
352The 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
357file system table
358.El
359.Sh DIAGNOSTICS
360Various, most of them are self-explanatory.
361.Pp
362.Dl XXXXX filesystem is not available
363.Pp
364The kernel does not support the respective filesystem type.
365Note that
366support 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 ) .
369Normally,
370.Nm
371or its subprocesses attempt to dynamically load a filesystem module if
372it has not been configured statically, using
373.Xr vfsload 3 .
374In this case, the above error message can also mean that you did not
375have 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
402After a successful
403.Nm ,
404the permissions on the original mount point determine if
405.Pa ..\&
406is accessible from the mounted file system.
407The minimum permissions for
408the mount point for traversal across the mount point in both
409directions to be possible for all users is 0111 (execute for all).
410.Sh HISTORY
411A
412.Nm
413utility appeared in
414.At v1 .
415.Sh BUGS
416It is possible for a corrupted file system to cause a crash.
417