man/libudev.xml

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   8 <!--
   9   SPDX-License-Identifier: LGPL-2.1+
  10
  11   Copyright © 2015 David Herrmann <dh.herrmann@gmail.com>
  12 -->
  13
  14 <refentry id="libudev"
  15   xmlns:xi="http://www.w3.org/2001/XInclude">
  16
  17   <refentryinfo>
  18     <title>libudev</title>
  19     <productname>systemd</productname>
  20
  21     <authorgroup>
  22       <author>
  23         <contrib>Developer</contrib>
  24         <firstname>David</firstname>
  25         <surname>Herrmann</surname>
  26         <email>dh.herrmann@gmail.com</email>
  27       </author>
  28     </authorgroup>
  29   </refentryinfo>
  30
  31   <refmeta>
  32     <refentrytitle>libudev</refentrytitle>
  33     <manvolnum>3</manvolnum>
  34   </refmeta>
  35
  36   <refnamediv>
  37     <refname>libudev</refname>
  38     <refpurpose>API for enumerating and introspecting local devices</refpurpose>
  39   </refnamediv>
  40
  41   <refsynopsisdiv>
  42     <funcsynopsis>
  43       <funcsynopsisinfo>#include &lt;libudev.h&gt;</funcsynopsisinfo>
  44     </funcsynopsis>
  45
  46     <cmdsynopsis>
  47       <command>pkg-config --cflags --libs libudev</command>
  48     </cmdsynopsis>
  49   </refsynopsisdiv>
  50
  51   <refsect1>
  52     <title>Description</title>
  53
  54     <para><filename>libudev.h</filename> provides APIs to introspect
  55     and enumerate devices on the local system.</para>
  56
  57     <para>All functions require a libudev context to operate. This
  58     context can be create via
  59     <citerefentry><refentrytitle>udev_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
  60     It is used to track library state and link objects together. No
  61     global state is used by libudev, everything is always linked to
  62     a udev context. Furthermore, multiple different udev contexts can
  63     be used in parallel by multiple threads. However, a single context
  64     must not be accessed by multiple threads in parallel. The caller
  65     is responsible for providing suitable locking if they intend to use
  66     it from multiple threads.</para>
  67
  68     <para>To introspect a local device on a system, a udev device
  69     object can be created via
  70     <citerefentry><refentrytitle>udev_device_new_from_syspath</refentrytitle><manvolnum>3</manvolnum></citerefentry>
  71     and friends. The device object allows one to query current state,
  72     read and write attributes and lookup properties of the device in
  73     question.</para>
  74
  75     <para>To enumerate local devices on the system, an enumeration
  76     object can be created via
  77     <citerefentry><refentrytitle>udev_enumerate_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
  78
  79     <para>To monitor the local system for hotplugged or unplugged
  80     devices, a monitor can be created via
  81     <citerefentry><refentrytitle>udev_monitor_new_from_netlink</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
  82
  83     <para>Whenever libudev returns a list of objects, the
  84     <citerefentry><refentrytitle>udev_list_entry</refentrytitle><manvolnum>3</manvolnum></citerefentry>
  85     API should be used to iterate, access and modify those lists.</para>
  86
  87     <para>Furthermore, libudev also exports legacy APIs that should
  88     not be used by new software (and as such are not documented as
  89     part of this manual). This includes the hardware database known
  90     as <constant>udev_hwdb</constant> (please use the new
  91     <citerefentry><refentrytitle>sd-hwdb</refentrytitle><manvolnum>3</manvolnum></citerefentry>
  92     API instead) and the <constant>udev_queue</constant> object to
  93     query the udev daemon (which should not be used by new software
  94     at all).</para>
  95   </refsect1>
  96
  97   <refsect1>
  98     <title>See Also</title>
  99     <para>
 100       <citerefentry><refentrytitle>udev_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 101       <citerefentry><refentrytitle>udev_device_new_from_syspath</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 102       <citerefentry><refentrytitle>udev_enumerate_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 103       <citerefentry><refentrytitle>udev_monitor_new_from_netlink</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 104       <citerefentry><refentrytitle>udev_list_entry</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 105       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 106       <citerefentry><refentrytitle>sd-device</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 107       <citerefentry><refentrytitle>sd-hwdb</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 108       <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 109     </para>
 110   </refsect1>
 111
 112 </refentry>