376 lines
10 KiB
Groff
376 lines
10 KiB
Groff
.\"
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.\" Copyright (c) 2002 Dima Dorfman.
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.\" All rights reserved.
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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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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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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.\" $FreeBSD$
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.\"
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.Dd April 21, 2013
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.Dt DEVFS 8
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.Os
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.Sh NAME
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.Nm devfs
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.Nd "DEVFS control"
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.Sh SYNOPSIS
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.Nm
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.Op Fl m Ar mount-point
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.Ar keyword
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.Ar argument ...
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.Sh DESCRIPTION
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The
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.Nm
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utility provides an interface to manipulate properties of
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.Xr devfs 5
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mounts.
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.Pp
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The
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.Ar keyword
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argument determines the context for
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the rest of the arguments.
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For example,
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most of the commands related to the rule subsystem must be preceded by the
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.Cm rule
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keyword.
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The following flags are common to all keywords:
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.Bl -tag -width 15n
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.It Fl m Ar mount-point
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Operate on
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.Ar mount-point ,
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which is expected to be a
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.Xr devfs 5
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mount.
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If this option is not specified,
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.Nm
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operates on
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.Pa /dev .
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.El
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.Ss Rule Subsystem
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The
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.Xr devfs 5
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rule subsystem provides a way for the administrator of a system to control
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the attributes of DEVFS nodes.
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.\" XXX devfs node? entry? what?
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Each DEVFS mount-point has a
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.Dq ruleset ,
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or a list of rules,
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associated with it.
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When a device driver creates a new node,
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all the rules in the ruleset associated with each mount-point are applied
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(see below) before the node becomes visible to the userland.
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This permits the administrator to change the properties,
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including the visibility,
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of certain nodes.
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For example, one might want to hide all disk nodes in a
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.Xr jail 2 Ns 's
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.Pa /dev .
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.Ss Rule Manipulation
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Rule manipulation commands follow the
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.Cm rule
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keyword.
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The following flags are common to all of the rule manipulation commands:
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.Bl -tag -width 15n
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.It Fl s Ar ruleset
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Operate on the ruleset with the number
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.Ar ruleset .
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If this is not specified,
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the commands operate on the ruleset currently associated with the
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specified mount-point.
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.El
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.Pp
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The following commands are recognized:
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.Bl -tag -width 15n
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.It Cm rule add Oo Ar rulenum Oc Ar rulespec
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Add the rule described by
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.Ar rulespec
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(defined below)
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to the ruleset.
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The rule has the number
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.Ar rulenum
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if it is explicitly specified;
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otherwise, the rule number is automatically determined by the kernel.
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.It Cm rule apply Ar rulenum | rulespec
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Apply rule number
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.Ar rulenum
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or the rule described by
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.Ar rulespec
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to the mount-point.
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Rules that are
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.Dq applied
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have their conditions checked against all nodes
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in the mount-point and the actions taken if they match.
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.It Cm rule applyset
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Apply all the rules in the ruleset to the mount-point
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(see above for the definition of
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.Dq apply ) .
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.It Cm rule del Ar rulenum
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Delete rule number
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.Ar rulenum
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from the ruleset.
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.It Cm rule delset
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Delete all rules from the ruleset.
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.It Cm rule show Op Ar rulenum
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Display the rule number
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.Ar rulenum ,
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or all the rules in the ruleset.
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The output lines (one line per rule) are expected to be valid
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.Ar rulespec Ns s .
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.It Cm rule showsets
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Report the numbers of existing rulesets.
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.It Cm ruleset Ar ruleset
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Set ruleset number
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.Ar ruleset
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as the current ruleset for the mount-point.
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.El
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.Ss Rule Specification
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Rules have two parts: the conditions and the actions.
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The conditions determine which DEVFS nodes the rule matches
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and the actions determine what should be done when a rule matches a node.
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For example, a rule can be written that sets the GID to
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.Dq Li operator
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for all devices of type tape.
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If the first token of a rule specification is a single dash
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.Pq Sq Fl ,
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rules are read from the standard input and the rest of the specification
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is ignored.
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.Pp
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The following conditions are recognized.
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Conditions are ANDed together when matching a device;
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if OR is desired, multiple rules can be written.
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.Bl -tag -width 15n
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.It Cm path Ar pattern
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Matches any node with a path that matches
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.Ar pattern ,
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which is interpreted as a
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.Xr glob 3 Ns -style
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pattern.
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.It Cm type Ar devtype
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Matches any node that is of type
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.Ar devtype .
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Valid types are
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.Cm disk , mem , tape
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and
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.Cm tty .
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.El
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.Pp
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The following actions are recognized.
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Although there is no explicit delimiter between conditions and actions,
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they may not be intermixed.
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.Bl -tag -width 15n
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.It Cm group Ar gid
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Set the GID of the node to
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.Ar gid ,
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which may be a group name
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(looked up in
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.Pa /etc/group )
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or number.
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.It Cm hide
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Hide the node.
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Nodes may later be revived manually with
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.Xr mknod 8
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or with the
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.Cm unhide
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action.
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.It Cm include Ar ruleset
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Apply all the rules in ruleset number
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.Ar ruleset
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to the node.
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This does not necessarily result in any changes to the node
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(e.g., if none of the rules in the included ruleset match).
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Include commands in the referenced
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.Ar ruleset
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are not resolved.
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.It Cm mode Ar filemode
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Set the file mode to
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.Ar filemode ,
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which is interpreted as in
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.Xr chmod 1 .
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.It Cm user Ar uid
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Set the UID to
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.Ar uid ,
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which may be a user name
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(looked up in
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.Pa /etc/passwd )
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or number.
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.It Cm unhide
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Unhide the node.
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.El
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.Sh IMPLEMENTATION NOTES
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Rulesets are created by the kernel at the first reference
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and destroyed when the last reference disappears.
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E.g., a ruleset is created when a rule is added to it or when it is set
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as the current ruleset for a mount-point, and
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a ruleset is destroyed when the last rule in it is deleted
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and no other references to it exist
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(i.e., it is not included by any rules and it is not the current ruleset
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for any mount-point).
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.Pp
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Ruleset number 0 is the default ruleset for all new mount-points.
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It is always empty, cannot be modified or deleted, and does not show up
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in the output of
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.Cm showsets .
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.Pp
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Rules and rulesets are unique to the entire system,
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not a particular mount-point.
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I.e., a
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.Cm showsets
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will return the same information regardless of the mount-point specified with
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.Fl m .
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The mount-point is only relevant when changing what its current ruleset is
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or when using one of the apply commands.
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.Sh FILES
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.Bl -tag -width "Pa /usr/share/examples/etc/devfs.conf" -compact
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.It Pa /etc/defaults/devfs.rules
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Default
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.Nm
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configuration file.
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.It Pa /etc/devfs.rules
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Local
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.Nm
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configuration file. Rulesets in here override those in
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.Pa /etc/defaults/devfs.rules
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with the same ruleset number, otherwise the two files are effectively merged.
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.It Pa /etc/devfs.conf
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Boot-time
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.Nm
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configuration file.
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.It Pa /usr/share/examples/etc/devfs.conf
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Example boot-time
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.Nm
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configuration file.
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.El
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.Sh EXAMPLES
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When the system boots,
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the only ruleset that exists is ruleset number 0;
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since the latter may not be modified, we have to create another ruleset
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before adding rules.
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Note that since most of the following examples do not specify
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.Fl m ,
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the operations are performed on
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.Pa /dev
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(this only matters for things that might change the properties of nodes).
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.Pp
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Specify that ruleset 10 should be the current ruleset for
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.Pa /dev
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(if it does not already exist, it is created):
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.Pp
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.Dl "devfs ruleset 10"
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.Pp
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Add a rule that causes all nodes that have a path that matches
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.Dq Li speaker
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(this is only
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.Pa /dev/speaker )
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to have the file mode 666 (read and write for all).
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Note that if any such nodes already exist, their mode will not be changed
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unless this rule (or ruleset) is explicitly applied (see below).
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The mode
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.Em will
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be changed if the node is created
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.Em after
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the rule is added
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(e.g., the
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.Pa atspeaker
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module is loaded after the above rule is added):
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.Pp
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.Dl "devfs rule add path speaker mode 666"
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.Pp
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Apply all the rules in the current ruleset to all the existing nodes.
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E.g., if the below rule was added after
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.Pa /dev/speaker
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was created,
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this command will cause its file mode to be changed to 666
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as prescribed by the rule:
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.Pp
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.Dl "devfs rule applyset"
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.Pp
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For all devices with a path that matches
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.Dq Li snp* ,
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set the file mode to 660 and the GID to
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.Dq Li snoopers .
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This permits users in the
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.Dq Li snoopers
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group to use the
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.Xr snp 4
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devices
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(quoting the argument to
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.Cm path
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is often necessary to disable the shell's globbing features):
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.Pp
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.Dl devfs rule add path "snp*" mode 660 group snoopers
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.Pp
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Add a rule to ruleset number 20.
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Since this ruleset is not the current ruleset for any mount-points,
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this rule is never applied automatically (unless ruleset 20 becomes
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a current ruleset for some mount-point at a later time):
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.Pp
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.Dl "devfs rule -s 20 add type disk group wheel"
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.Pp
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Explicitly apply all rules in ruleset number 20 to the DEVFS mount on
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.Pa /my/jail/dev .
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It does not matter that ruleset 20 is not the current ruleset for that
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mount-point; the rules are still applied:
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.Pp
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.Dl "devfs -m /my/jail/dev rule -s 20 applyset"
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.Pp
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Since the following rule has no conditions, the action
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.Pq Cm hide
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will be applied to all nodes:
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.Pp
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.Dl "devfs rule apply hide"
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.Pp
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Since hiding all nodes is not very useful, we can undo it.
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The following applies
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.Cm unhide
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to all the nodes,
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causing them to reappear:
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.Pp
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.Dl "devfs rule apply unhide"
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.Pp
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Add all the rules from the file
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.Pa my_rules
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to ruleset 10:
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.Pp
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.Dl "devfs rule -s 10 add - < my_rules"
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.Pp
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The below copies all the rules from ruleset 20 into ruleset 10.
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The rule numbers are preserved,
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but ruleset 10 may already have rules with non-conflicting numbers
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(these will be preserved).
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Since
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.Cm show
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outputs valid rules,
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this feature can be used to copy rulesets:
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.Pp
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.Dl "devfs rule -s 20 show | devfs rule -s 10 add -"
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.Sh SEE ALSO
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.Xr chmod 1 ,
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.Xr jail 2 ,
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.Xr glob 3 ,
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.Xr devfs 5 ,
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.Xr devfs.conf 5 ,
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.Xr devfs.rules 5 ,
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.Xr chown 8 ,
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.Xr jail 8 ,
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.Xr mknod 8
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.Sh AUTHORS
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.An Dima Dorfman
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