man/libudev.xml

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   7 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
   8
   9 <refentry id="libudev"
  10   xmlns:xi="http://www.w3.org/2001/XInclude">
  11
  12   <refentryinfo>
  13     <title>libudev</title>
  14     <productname>systemd</productname>
  15   </refentryinfo>
  16
  17   <refmeta>
  18     <refentrytitle>libudev</refentrytitle>
  19     <manvolnum>3</manvolnum>
  20   </refmeta>
  21
  22   <refnamediv>
  23     <refname>libudev</refname>
  24     <refpurpose>API for enumerating and introspecting local devices</refpurpose>
  25   </refnamediv>
  26
  27   <refsynopsisdiv>
  28     <funcsynopsis>
  29       <funcsynopsisinfo>#include &lt;libudev.h&gt;</funcsynopsisinfo>
  30     </funcsynopsis>
  31
  32     <cmdsynopsis>
  33       <command>pkg-config --cflags --libs libudev</command>
  34     </cmdsynopsis>
  35   </refsynopsisdiv>
  36
  37   <refsect1>
  38     <title>Description</title>
  39
  40     <para><filename>libudev.h</filename> provides an API to introspect and enumerate devices on the local
  41     system. This library is supported, but should not be used in new projects. Please see
  42     <citerefentry><refentrytitle>sd-device</refentrytitle><manvolnum>3</manvolnum></citerefentry> for an
  43     equivalent replacement with a more modern API.</para>
  44
  45     <para>All functions require a libudev context to operate. This
  46     context can be created via
  47     <citerefentry><refentrytitle>udev_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
  48     It is used to track library state and link objects together. No
  49     global state is used by libudev, everything is always linked to
  50     a udev context.</para>
  51
  52     <xi:include href="threads-aware.xml" xpointer="strict"/>
  53     <xi:include href="threads-aware.xml" xpointer="getenv"/>
  54
  55     <para>To introspect a local device on a system, a udev device
  56     object can be created via
  57     <citerefentry><refentrytitle>udev_device_new_from_syspath</refentrytitle><manvolnum>3</manvolnum></citerefentry>
  58     and friends. The device object allows one to query current state,
  59     read and write attributes and lookup properties of the device in
  60     question.</para>
  61
  62     <para>To enumerate local devices on the system, an enumeration
  63     object can be created via
  64     <citerefentry><refentrytitle>udev_enumerate_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
  65
  66     <para>To monitor the local system for hotplugged or unplugged
  67     devices, a monitor can be created via
  68     <citerefentry><refentrytitle>udev_monitor_new_from_netlink</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
  69
  70     <para>Whenever libudev returns a list of objects, the
  71     <citerefentry><refentrytitle>udev_list_entry</refentrytitle><manvolnum>3</manvolnum></citerefentry>
  72     API should be used to iterate, access and modify those lists.</para>
  73
  74     <para>Furthermore, libudev also exports legacy APIs that should
  75     not be used by new software (and as such are not documented as
  76     part of this manual). This includes the hardware database known
  77     as <constant>udev_hwdb</constant> (please use the new
  78     <citerefentry><refentrytitle>sd-hwdb</refentrytitle><manvolnum>3</manvolnum></citerefentry>
  79     API instead) and the <constant>udev_queue</constant> object to
  80     query the udev daemon (which should not be used by new software
  81     at all).</para>
  82   </refsect1>
  83
  84   <refsect1>
  85     <title>See Also</title>
  86     <para><simplelist type="inline">
  87       <member><citerefentry><refentrytitle>udev_new</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
  88       <member><citerefentry><refentrytitle>udev_device_new_from_syspath</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
  89       <member><citerefentry><refentrytitle>udev_enumerate_new</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
  90       <member><citerefentry><refentrytitle>udev_monitor_new_from_netlink</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
  91       <member><citerefentry><refentrytitle>udev_list_entry</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
  92       <member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
  93       <member><citerefentry><refentrytitle>sd-device</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
  94       <member><citerefentry><refentrytitle>sd-hwdb</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
  95       <member><citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
  96     </simplelist></para>
  97   </refsect1>
  98
  99 </refentry>