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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"

"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

<refentry id="sd_booted">

<refentryinfo>

<title>sd_booted</title>

<productname>systemd</productname>

<authorgroup>

<author>

<contrib>Developer</contrib>

<firstname>Lennart</firstname>

<surname>Poettering</surname>

<email>lennart@poettering.net</email>

</author>

</authorgroup>

</refentryinfo>

<refmeta>

<refentrytitle>sd_booted</refentrytitle>

<manvolnum>3</manvolnum>

</refmeta>

<refnamediv>

<refname>sd_booted</refname>

<refpurpose>Test whether the system is running the systemd init system</refpurpose>

</refnamediv>

<refsynopsisdiv>

<funcsynopsis>

<funcsynopsisinfo>#include &lt;systemd/sd-daemon.h&gt;</funcsynopsisinfo>

<funcprototype>

<funcdef>int <function>sd_booted</function></funcdef>

<paramdef>void</paramdef>

</funcprototype>

</funcsynopsis>

</refsynopsisdiv>

<refsect1>

<title>Description</title>

<para><function>sd_booted()</function> checks whether

the system was booted up using the systemd init system.</para>

</refsect1>

<refsect1>

<title>Return Value</title>

<para>On failure, this call returns a negative

errno-style error code. If the system was booted up

with systemd as init system, this call returns a

positive return value, zero otherwise.</para>

</refsect1>

<refsect1>

<title>Notes</title>

<para>This function is provided by the reference

implementation of APIs for new-style daemons and

distributed with the systemd package. The algorithm it

implements is simple, and can easily be reimplemented

in daemons if it is important to support this

interface without using the reference

implementation.</para>

<para>Internally, this function checks whether the

<filename>/sys/fs/cgroup/systemd</filename> virtual file

system is mounted, by comparing the st_dev value of

the <function>stat()</function> data of

<filename>/sys/fs/cgroup</filename> and

<filename>/sys/fs/cgroup/systemd</filename>.</para>

<para>For details about the algorithm check the

liberally licensed reference implementation sources:

<ulink url="http://cgit.freedesktop.org/systemd/systemd/plain/src/sd-daemon.c"/>

resp. <ulink

url="http://cgit.freedesktop.org/systemd/systemd/plain/src/systemd/sd-daemon.h"/></para>

<para><function>sd_booted()</function> is implemented

in the reference implementation's

<filename>sd-daemon.c</filename> and

<filename>sd-daemon.h</filename> files. These

interfaces are available as shared library, which can

be compiled and linked to with the

<literal>libsystemd-daemon</literal>

<citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>

file. Alternatively, applications consuming these APIs

may copy the implementation into their source

tree. For more details about the reference

implementation see

<citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>

<para>If the reference implementation is used as

drop-in files and -DDISABLE_SYSTEMD is set during

compilation this function will always return 0 and

otherwise become a NOP.</para>

</refsect1>

<refsect1>

<title>See Also</title>

<para>

<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,

<citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>

</para>

</refsect1>

</refentry>