man/libudev.xml

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