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<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
This file is part of systemd.
Copyright 2010 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->
<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 <systemd/sd-daemon.h></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>7</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>7</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
|
