man/sd_booted.xml

   1 <?xml version='1.0'?> <!--*-nxml-*-->
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
   3         "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4
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   8   Copyright 2010 Lennart Poettering
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  23
  24 <refentry id="sd_booted">
  25
  26         <refentryinfo>
  27                 <title>sd_booted</title>
  28                 <productname>systemd</productname>
  29
  30                 <authorgroup>
  31                         <author>
  32                                 <contrib>Developer</contrib>
  33                                 <firstname>Lennart</firstname>
  34                                 <surname>Poettering</surname>
  35                                 <email>lennart@poettering.net</email>
  36                         </author>
  37                 </authorgroup>
  38         </refentryinfo>
  39
  40         <refmeta>
  41                 <refentrytitle>sd_booted</refentrytitle>
  42                 <manvolnum>3</manvolnum>
  43         </refmeta>
  44
  45         <refnamediv>
  46                 <refname>sd_booted</refname>
  47                 <refpurpose>Test whether the system is running the systemd init system</refpurpose>
  48         </refnamediv>
  49
  50         <refsynopsisdiv>
  51                 <funcsynopsis>
  52                         <funcsynopsisinfo>#include &lt;systemd/sd-daemon.h&gt;</funcsynopsisinfo>
  53
  54                         <funcprototype>
  55                                 <funcdef>int <function>sd_booted</function></funcdef>
  56                                 <paramdef>void</paramdef>
  57                         </funcprototype>
  58                 </funcsynopsis>
  59         </refsynopsisdiv>
  60
  61         <refsect1>
  62                 <title>Description</title>
  63                 <para><function>sd_booted()</function> checks whether
  64                 the system was booted up using the systemd init system.</para>
  65         </refsect1>
  66
  67         <refsect1>
  68                 <title>Return Value</title>
  69
  70                 <para>On failure, this call returns a negative
  71                 errno-style error code. If the system was booted up
  72                 with systemd as init system, this call returns a
  73                 positive return value, zero otherwise.</para>
  74         </refsect1>
  75
  76         <refsect1>
  77                 <title>Notes</title>
  78
  79                 <para>This function is provided by the reference
  80                 implementation of APIs for new-style daemons and
  81                 distributed with the systemd package. The algorithm it
  82                 implements is simple, and can easily be reimplemented
  83                 in daemons if it is important to support this
  84                 interface without using the reference
  85                 implementation.</para>
  86
  87                 <para>Internally, this function checks whether the
  88                 directory <filename>/run/systemd/system/</filename>
  89                 exists. A simple check like this can also be
  90                 implemented trivially in shell or any other
  91                 language.</para>
  92
  93                 <para>For details about the algorithm check the
  94                 liberally licensed reference implementation sources:
  95                 <ulink url="http://cgit.freedesktop.org/systemd/systemd/plain/src/libsystemd-daemon/sd-daemon.c"/>
  96                 and <ulink
  97                 url="http://cgit.freedesktop.org/systemd/systemd/plain/src/systemd/sd-daemon.h"/></para>
  98
  99                 <para><function>sd_booted()</function> is implemented
 100                 in the reference implementation's
 101                 <filename>sd-daemon.c</filename> and
 102                 <filename>sd-daemon.h</filename> files. These
 103                 interfaces are available as shared library, which can
 104                 be compiled and linked to with the
 105                 <constant>libsystemd-daemon</constant> <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 106                 file. Alternatively, applications consuming these APIs
 107                 may copy the implementation into their source
 108                 tree. For more details about the reference
 109                 implementation see
 110                 <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
 111
 112                 <para>If the reference implementation is used as
 113                 drop-in files and -DDISABLE_SYSTEMD is set during
 114                 compilation, this function will always return 0 and
 115                 otherwise become a NOP.</para>
 116         </refsect1>
 117
 118         <refsect1>
 119                 <title>See Also</title>
 120                 <para>
 121                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 122                         <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 123                 </para>
 124         </refsect1>
 125
 126 </refentry>