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37 .Nd mount a Fuse file system daemon
43 .Op Fl D Ar fuse_daemon
44 .Op Fl O Ar daemon_opts
49 .Op Fl o Ar option ...
51 .Op Ar fuse_daemon ...
53 Basic usage is to start a fuse daemon on the given
55 file. In practice, the daemon is assigned a
57 file automatically, which can then be indentified via
59 That special file can then be mounted by
62 However, the procedure of spawning a daemon will usually be automated
63 so that it is performed by
65 If the command invoking a given
67 is appended to the list of arguments,
71 via that command. In that way the
73 will be instructed to attach itself to
75 From that on mounting goes as in the simple case. (See
80 argument will normally be treated as the path of the special file to mount.
88 will look for a suitable free fuse device by itself.
92 is an integer it will be interpreted as the number
93 of the file descriptor of an already open fuse device
94 (used when the Fuse library invokes
99 The options are as follows:
100 .Bl -tag -width indent
101 .It Fl A , Ic --reject-allow_other
104 mount flag. Intended for use in scripts and the
108 Run in safe mode (i.e. reject invoking a filesystem daemon)
111 .It Fl D, Ic --daemon Ar daemon
114 .It Fl O, Ic --daemon_opts Ar opts
117 to the daemon's command line
118 .It Fl s, Ic --special Ar special
122 .It Fl m, Ic --mountpath Ar node
127 .It Fl V, Ic --version
128 Show version information
130 Mount options are specified via
132 The following options are available (and also their negated versions,
133 by prefixing them with
135 .Bl -tag -width indent
136 .It Cm default_permissions
137 Enable traditional (file mode based) permission checking in kernel
140 .Sx STRICT ACCESS POLICY .
141 Only root can use this option
142 .It Cm max_read Ns = Ns Ar n
143 Limit size of read requests to
146 Refuse shared mounting of the daemon. This is the default behaviour,
147 to allow sharing, expicitly use
149 .It Cm neglect_shares
150 Do not refuse unmounting if there are secondary mounts
151 .It Cm push_symlinks_in
152 Prefix absolute symlinks with the mountpoint
156 Besides the above mount options, there is a set of pseudo-mount options which
157 are supported by the Fuse library. One can list these by passing
159 to a Fuse daemon. Most of these options have effect only on the behaviour of
160 the daemon (that is, their scope is limited to userspace). However,
161 there are some which do require in-kernel support.
162 Currently the options supported by the kernel are:
163 .Bl -tag -width indent
165 Bypass the buffer cache system
167 By default cached buffers of a given file are flushed at each
169 This option disables this behaviour
172 Usually users do not need to use
174 directly, as the Fuse library enables Fuse daemons to invoke
178 .Dl fuse_daemon device mountpoint
180 has the same effect as
182 .Dl mount_fusefs auto mountpoint fuse_daemon
184 This is the recommended usage when you want basic usage
185 (eg, run the daemon at a low privilege level but mount it as root).
186 .Sh STRICT ACCESS POLICY
187 The strict access policy for Fuse filesystems lets one to use the filesystem
188 only if the filesystem daemon has the same credentials (uid, real uid, gid,
189 real gid) as the user.
191 This is applied for Fuse mounts by default and only root can mount without
192 the strict access policy (ie. the
196 This is to shield users from the daemon
198 on their I/O activities.
200 Users might opt to willingly relax strict access policy (as far they
201 are concerned) by doing their own secondary mount (See
202 .Sx SHARED MOUNTS ) .
204 A Fuse daemon can be shared (ie. mounted multiple times).
205 When doing the first (primary) mount, the spawner and the mounter of the daemon
206 must have the same uid, or the mounter should be the superuser.
208 After the primary mount is in place, secondary mounts can be done by anyone
209 unless this feature is disabled by
211 The behaviour of a secondary mount is analogous to that of symbolic
212 links: they redirect all filesystem operations to the primary mount.
214 Doing a secondary mount is like signing an agreement: by this action, the mounter
215 agrees that the Fuse daemon can trace her I/O activities. From then on
216 she is not banned from using the filesystem (either via her own mount or
217 via the primary mount), regardless whether
221 The device name of a secondary mount is the device name of the corresponding
222 primary mount, followed by a '#' character and the index of the secondary
226 System administrators might want to use a custom mount policy (ie., one going
229 sysctl). The primary tool for such purposes is
233 is capable of invoking an arbitrary program, one must be careful when doing this.
235 is designed in a way such that it makes that easy. For this purpose,
236 there are options which disable certain risky features (ie.
240 and command line parsing is done in a flexible way: mixing options and
241 non-options is allowed, but processing them stops at the third non-option
242 argument (after the first two has been utilized as device and mountpoint).
243 The rest of the command line specifies the daemon and its arguments.
244 (Alternatively, the daemon, the special and the mount path can be
245 specified using the respective options.) Note that
247 ignores the environment variable
249 and always behaves as described.
251 In general, to be as scripting /
253 friendly as possible, no information has a fixed
254 position in the command line, but once a given piece of information is
255 provided, subsequent arguments/options cannot override it (with the
256 exception of some non-critical ones).
258 .Bl -tag -width ".Ev MOUNT_FUSEFS_SAFE"
259 .It Ev MOUNT_FUSEFS_SAFE
260 This has the same effect as the
263 .It Ev MOUNT_FUSEFS_VERBOSE
264 This has the same effect as the
267 .It Ev MOUNT_FUSEFS_IGNORE_UNKNOWN
270 will ignore uknown mount options.
271 .It Ev MOUNT_FUSEFS_CALL_BY_LIB
272 Adjust behaviour to the needs of the FUSE library. Currently it effects
276 Although the following variables do not have any effect on
278 itself, they affect the behaviour of fuse daemons:
279 .Bl -tag -width ".Ev FUSE_DEV_NAME"
281 Device to attach. If not set, the multiplexer path
285 File desciptor of an opened Fuse device to use. Overrides
288 If set, the library will not attempt to mount the filesystem, even
289 if a mountpoint argument is supplied.
292 .Bl -tag -width /dev/fuse
294 Fuse device with which the kernel and Fuse daemons can communicate.
296 The multiplexer path. An
298 performed on it automatically is passed to a free Fuse device by the kernel
299 (which might be created just for this puprose).
302 Mount the example filesystem in the Fuse distribution (from its directory):
305 .Dl ./fusexmp /mnt/fuse
309 .Dl mount_fusefs auto /mnt/fuse ./fusexmp
311 Doing the same in two steps, using
314 .Dl FUSE_DEV_NAME=/dev/fuse ./fusexmp &&
315 .Dl mount_fusefs /dev/fuse /mnt/fuse
317 A script wrapper for fusexmp which ensures that
319 does not call any external utility and also provides a hacky
320 (non race-free) automatic device selection:
324 .Dl FUSE_DEV_NAME=/dev/fuse fusexmp
325 .Dl mount_fusefs -S /dev/fuse /mnt/fuse \(lq$@\(rq
333 appears as the part of the FreeBSD implementation of the Fuse userspace filesystem
334 framework (see http://fuse.sourceforge.net). This user interface is FreeBSD specific.
336 Secondary mounts should be unmounted via their device name. If an attempt is
337 made to be unmount them via their filesystem root path, the unmount request
338 will be forwarded to the primary mount path.
339 In general, unmounting by device name is less error-prone than by mount path
340 (although the latter will also work under normal circumstances).
342 If the daemon is specified via the
346 options, it will be invoked via
348 and the daemon's command line will also have an
350 control operator appended, so that we do not have to wait for its termination.
351 You should use a simple command line when invoking the daemon via these options.
354 is treated as a multiplexer if and only if it is literally the same as
358 Other paths which are equivalent with