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logind: port over to use scopes+slices for all cgroup stuff
[elogind.git] / 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
5 <!--
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8   Copyright 2010 Lennart Poettering
9
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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>