man/libudev.xml

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  13   Copyright 2015 David Herrmann <dh.herrmann@gmail.com>
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  28
  29 <refentry id="libudev"
  30   xmlns:xi="http://www.w3.org/2001/XInclude">
  31
  32   <refentryinfo>
  33     <title>libudev</title>
  34     <productname>systemd</productname>
  35
  36     <authorgroup>
  37       <author>
  38         <contrib>Developer</contrib>
  39         <firstname>David</firstname>
  40         <surname>Herrmann</surname>
  41         <email>dh.herrmann@gmail.com</email>
  42       </author>
  43     </authorgroup>
  44   </refentryinfo>
  45
  46   <refmeta>
  47     <refentrytitle>libudev</refentrytitle>
  48     <manvolnum>3</manvolnum>
  49   </refmeta>
  50
  51   <refnamediv>
  52     <refname>libudev</refname>
  53     <refpurpose>API for enumerating and introspecting local devices</refpurpose>
  54   </refnamediv>
  55
  56   <refsynopsisdiv>
  57     <funcsynopsis>
  58       <funcsynopsisinfo>#include &lt;libudev.h&gt;</funcsynopsisinfo>
  59     </funcsynopsis>
  60
  61     <cmdsynopsis>
  62       <command>pkg-config --cflags --libs libudev</command>
  63     </cmdsynopsis>
  64   </refsynopsisdiv>
  65
  66   <refsect1>
  67     <title>Description</title>
  68
  69     <para><filename>libudev.h</filename> provides APIs to introspect
  70     and enumerate devices on the local system.</para>
  71
  72     <para>All functions require a libudev context to operate. This
  73     context can be create via
  74     <citerefentry><refentrytitle>udev_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
  75     It is used to track library state and link objects together. No
  76     global state is used by libudev, everything is always linked to
  77     a udev context. Furthermore, multiple different udev contexts can
  78     be used in parallel by multiple threads. However, a single context
  79     must not be accessed by multiple threads in parallel. The caller
  80     is responsible for providing suitable locking if they intend to use
  81     it from multiple threads.</para>
  82
  83     <para>To introspect a local device on a system, a udev device
  84     object can be created via
  85     <citerefentry><refentrytitle>udev_device_new_from_syspath</refentrytitle><manvolnum>3</manvolnum></citerefentry>
  86     and friends. The device object allows one to query current state,
  87     read and write attributes and lookup properties of the device in
  88     question.</para>
  89
  90     <para>To enumerate local devices on the system, an enumeration
  91     object can be created via
  92     <citerefentry><refentrytitle>udev_enumerate_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
  93
  94     <para>To monitor the local system for hotplugged or unplugged
  95     devices, a monitor can be created via
  96     <citerefentry><refentrytitle>udev_monitor_new_from_netlink</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
  97
  98     <para>Whenever libudev returns a list of objects, the
  99     <citerefentry><refentrytitle>udev_list_entry</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 100     API should be used to iterate, access and modify those lists.</para>
 101
 102     <para>Furthermore, libudev also exports legacy APIs that should
 103     not be used by new software (and as such are not documented as
 104     part of this manual). This includes the hardware database known
 105     as <constant>udev_hwdb</constant> (please use the new
 106     <citerefentry><refentrytitle>sd-hwdb</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 107     API instead) and the <constant>udev_queue</constant> object to
 108     query the udev daemon (which should not be used by new software
 109     at all).</para>
 110   </refsect1>
 111
 112   <refsect1>
 113     <title>See Also</title>
 114     <para>
 115       <citerefentry><refentrytitle>udev_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 116       <citerefentry><refentrytitle>udev_device_new_from_syspath</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 117       <citerefentry><refentrytitle>udev_enumerate_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 118       <citerefentry><refentrytitle>udev_monitor_new_from_netlink</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 119       <citerefentry><refentrytitle>udev_list_entry</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 120       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 121       <citerefentry><refentrytitle>sd-device</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 122       <citerefentry><refentrytitle>sd-hwdb</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 123       <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 124     </para>
 125   </refsect1>
 126
 127 </refentry>