217 lines
6.6 KiB
Groff
217 lines
6.6 KiB
Groff
.\" $NetBSD: mount_portal.8,v 1.10 1999/08/16 06:55:27 bgrayson Exp $
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.\"
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.\" Copyright (c) 1993, 1994
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" This code is derived from software donated to Berkeley by
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.\" Jan-Simon Pendry.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)mount_portal.8 8.3 (Berkeley) 3/27/94
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.\"
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.Dd March 27, 1994
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.Dt MOUNT_PORTAL 8
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.Os BSD 4.4
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.Sh NAME
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.Nm mount_portal
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.Nd mount the portal daemon
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.Sh SYNOPSIS
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.Nm ""
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.Op Fl o Ar options
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.Ar /etc/portal.conf
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.Ar mount_point
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.Sh DESCRIPTION
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The
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.Nm
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command attaches an instance of the portal daemon
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to the global filesystem namespace.
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The conventional mount point is
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.Pa /p .
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This command is normally executed by
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.Xr mount 8
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at boot time.
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.Pp
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The options are as follows:
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.Bl -tag -width indent
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.It Fl o
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Options are specified with a
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.Fl o
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flag followed by a comma separated string of options.
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See the
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.Xr mount 8
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man page for possible options and their meanings.
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.El
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.Pp
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The portal daemon provides an
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.Em open
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service.
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Objects opened under the portal mount point are
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dynamically created by the portal daemon according
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to rules specified in the named configuration file.
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Using this mechanism allows descriptors such as sockets
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to be made available in the filesystem namespace.
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.Pp
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The portal daemon works by being passed the full pathname
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of the object being opened.
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The daemon creates an appropriate descriptor according
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to the rules in the configuration file, and then passes the descriptor back
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to the calling process as the result of the open system call.
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.Sh NAMESPACE
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By convention, the portal daemon divides the namespace into sub-namespaces,
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each of which handles objects of a particular type.
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.Pp
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Currently, four sub-namespaces are implemented:
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.Pa tcp
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.Pa fs
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.Pa rfilter
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and
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.Pa wfilter .
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The
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.Pa tcp
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namespace takes a hostname and a port (slash separated) and
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creates an open TCP/IP connection.
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The
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.Pa fs
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namespace opens the named file, starting back at the root directory.
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This can be used to provide a controlled escape path from
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a chrooted environment.
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The
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.Pa rfilter
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and
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.Pa wfilter
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namespaces open a pipe to a process, typically a data-filter such
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as compression or decompression programs. The
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.Pa rfilter
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namespace opens a read-only pipe, while the
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.Pa wfilter
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namespace opens a write-only pipe. See the EXAMPLES section
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below for more examples.
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.Sh "CONFIGURATION FILE"
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The configuration file contains a list of rules.
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Each rule takes one line and consists of two or more
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whitespace separated fields.
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A hash (``#'') character causes the remainder of a line to
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be ignored. Blank lines are ignored.
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.Pp
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The first field is a pathname prefix to match
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against the requested pathname.
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If a match is found, the second field
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tells the daemon what type of object to create.
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Subsequent fields are passed to the creation function.
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The
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.Pa rfilter
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and
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.Pa wfilter
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namespaces have additional meanings for the remaining fields.
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The third field specifies a prefix that is to be stripped off of
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the passed name before passing it on to the pipe program. If the
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prefix does not match, no stripping is performed. The fourth
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argument specifies the program to use for the pipe. Any
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remaining fields are passed to the pipe program. If the
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string
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.Dq Li "%s"
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exists within these remaining fields, it will be replaced by the
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path after stripping is performed. If there is no field after
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the program name,
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.Dq Li "%s"
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will be assumed, to maintain similarity with the
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.Pa tcp
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and
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.Pa fs
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namespaces.
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.Sh EXAMPLES
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A tutorial and several examples are provided in
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/usr/share/examples/mount_portal. The following is an example
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configuration file.
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.Bd -literal
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# @(#)portal.conf 5.1 (Berkeley) 7/13/92
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tcp/ tcp tcp/
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fs/ file fs/
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echo/ rfilter echo/ echo %s
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echo_nostrip/ rfilter nostrip echo %s
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echo_noslash rfilter echo_noslash echo %s
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gzcat/ rfilter gzcat/ gzcat %s
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gzip/ wfilter gzip/ gzip > %s
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gzip9/ wfilter gzip9/ gzip -9 > %s
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ftp/ rfilter ftp/ ftp -Vo - %s
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ftp:// rfilter nostrip ftp -Vo - %s
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http:// rfilter nostrip ftp -Vo - %s
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bzcat/ rfilter bzcat/ bzcat %s
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nroff/ rfilter nroff/ nroff -man %s
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.Ed
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As is true with many other filesystems, a weird sense of humor is
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handy.
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Notice that after the keynames, like nroff/ and bzcat/, we
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typically use another slash. In reality, the
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.Nm
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process changes directory to /, which makes the subsequent slash
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unnecessary. However, the extra slash provides a visual hint
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that we are not operating on an ordinary file. An alternative
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would be to change the configuration file to something like:
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.Bd -literal
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nroff% rfilter nroff% nroff -man
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.Ed
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One might then use
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.Bd -literal
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less /p/nroff%/usr/share/man/man8/mount_portal.8
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.Ed
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.Sh FILES
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.Bl -tag -width /p/* -compact
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.It Pa /p/*
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.El
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.Sh SEE ALSO
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.Xr mount 2 ,
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.Xr unmount 2 ,
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.Xr fstab 5 ,
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.Xr mount 8
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.Sh CAVEATS
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This filesystem may not be NFS-exported.
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.Sh HISTORY
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The
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.Nm
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utility first appeared in
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.Bx 4.4 . The
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.Pa rfilter
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and
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.Pa wfilter
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capabilities first appeared in
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.Nx 1.5 .
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