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<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [
<!ENTITY % entities SYSTEM "custom-entities.ent" >
%entities;
]>
<!--
This file is part of systemd.
Copyright 2015 David Herrmann <dh.herrmann@gmail.com>
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->
<refentry id="libudev"
xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>libudev</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>Developer</contrib>
<firstname>David</firstname>
<surname>Herrmann</surname>
<email>dh.herrmann@gmail.com</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>libudev</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>libudev</refname>
<refpurpose>API for enumerating and introspecting local devices</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include <libudev.h></funcsynopsisinfo>
</funcsynopsis>
<cmdsynopsis>
<command>pkg-config --cflags --libs libudev</command>
</cmdsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><filename>libudev.h</filename> provides APIs to introspect
and enumerate devices on the local system.</para>
<para>All functions require a libudev context to operate. This
context can be create via
<citerefentry><refentrytitle>udev_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
It is used to track library state and link objects together. No
global state is used by libudev, everything is always linked to
a udev context. Furthermore, multiple different udev contexts can
be used in parallel by multiple threads. However, a single context
must not be accessed by multiple threads in parallel. The caller
is responsible of providing suitable locking if they intend to use
it from multiple threads.</para>
<para>To introspect a local device on a system, a udev device
object can be created via
<citerefentry><refentrytitle>udev_device_new_from_syspath</refentrytitle><manvolnum>3</manvolnum></citerefentry>
and friends. The device object allows to query current state,
read and write attributes and lookup properties of the device in
question.</para>
<para>To enumerate local devices on the system, an enumeration
object can be created via
<citerefentry><refentrytitle>udev_enumerate_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
<para>To monitor the local system for hotplugged or unplugged
devices, a monitor can be created via
<citerefentry><refentrytitle>udev_monitor_new_from_netlink</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
<para>Whenever libudev returns a list of objects, the
<citerefentry><refentrytitle>udev_list_entry</refentrytitle><manvolnum>3</manvolnum></citerefentry>
API should be used to iterate, access and modify those lists.</para>
<para>Furthermore, libudev also exports legacy APIs that should
not be used by new software (and as such are not documented as
part of this manual). This includes the hardware-database known
as <constant>udev_hwdb</constant> (please use the new
<citerefentry><refentrytitle>sd-hwdb</refentrytitle><manvolnum>3</manvolnum></citerefentry>
API instead) and the <constant>udev_queue</constant> object to
query the udev-daemon (which should not be used by new software
at all).</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>udev_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>udev_device_new_from_syspath</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>udev_enumerate_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>udev_monitor_new_from_netlink</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>udev_list_entry</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd-device</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd-hwdb</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
|
