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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-daemon">
+
+        <refentryinfo>
+                <title>sd-daemon</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-daemon</refentrytitle>
+                <manvolnum>7</manvolnum>
+        </refmeta>
+
+        <refnamediv>
+                <refname>sd-daemon</refname>
+                <refpurpose>Reference implementation of APIs for
+                new-style daemons</refpurpose>
+        </refnamediv>
+
+        <refsynopsisdiv>
+                <funcsynopsis>
+                        <funcsynopsisinfo>#include "sd-daemon.h"</funcsynopsisinfo>
+                </funcsynopsis>
+        </refsynopsisdiv>
+
+        <refsect1>
+                <title>Description</title>
+
+                <para><filename>sd-daemon.c</filename> and
+                <filename>sd-daemon.h</filename> provide a reference
+                implementation of various APIs for new-style daemons,
+                as implemented by the
+                <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+                init system.</para>
+
+                <para>See
+                <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+                <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+                <citerefentry><refentrytitle>sd_booted</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+                <citerefentry><refentrytitle>sd_is_fifo</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+                for more information about the functions
+                implemented. In addition to these functions a couple
+                of logging prefixes are defined as macros:</para>
+
+                <programlisting>#define SD_EMERG   "&lt;0&gt;"  /* system is unusable */
+#define SD_ALERT   "&lt;1&gt;"  /* action must be taken immediately */
+#define SD_CRIT    "&lt;2&gt;"  /* critical conditions */
+#define SD_ERR     "&lt;3&gt;"  /* error conditions */
+#define SD_WARNING "&lt;4&gt;"  /* warning conditions */
+#define SD_NOTICE  "&lt;5&gt;"  /* normal but significant condition */
+#define SD_INFO    "&lt;6&gt;"  /* informational */
+#define SD_DEBUG   "&lt;7&gt;"  /* debug-level messages */</programlisting>
+
+                <para>These prefixes are intended to be used in
+                conjunction with STDERR-based logging as implemented
+                by systemd. If a systemd service definition file is
+                configured with <varname>StandardError=syslog</varname>
+                or <varname>StandardError=kmsg</varname> these
+                prefixes can be used to encode a log level in lines
+                printed. This is similar to the kernel
+                <function>printk()</function>-style logging. See
+                <citerefentry><refentrytitle>klogctl</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+                for more information.</para>
+
+                <para>The log levels are identical to
+                <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>'s
+                log level system. To use these prefixes simply prefix
+                every line with one of these strings. A line that is
+                not prefixed will be logged at the default log level
+                SD_INFO.</para>
+
+                <example>
+                        <title>Hello World</title>
+
+                        <para>A daemon may log with the log level
+                        NOTICE by issuing this call:</para>
+
+                        <programlisting>fprintf(stderr, SD_NOTICE "Hello World!\n");</programlisting>
+                </example>
+        </refsect1>
+
+        <refsect1>
+                <title>Notes</title>
+
+                <para>These interfaces are provided by the reference
+                implementation of APIs for new-style daemons and
+                distributed with the systemd package. The algorithms
+                they implement are simple, and can easily be
+                reimplemented in daemons if it is important to support
+                this interface without using the reference
+                implementation. See the respective function man pages
+                for details.</para>
+
+                <para>In addition, for details about the algorithms
+                check the liberally licensed reference implementation
+                sources:
+                <ulink url="http://cgit.freedesktop.org/systemd/tree/src/sd-daemon.c"/>
+                resp. <ulink url="http://cgit.freedesktop.org/systemd/tree/src/sd-daemon.h"/></para>
+
+                <para>These APIs are implemented in the reference
+                implementation's drop-in
+                <filename>sd-daemon.c</filename> and
+                <filename>sd-daemon.h</filename> files. It is
+                recommended that applications consuming these APIs copy
+                the implementation into their source tree, either
+                verbatim or in excerpts. These interfaces are
+                currently not available in a dynamic library.</para>
+
+                <para>The functions directly related to new-style
+                daemons become NOPs when -DDISABLE_SYSTEMD is set
+                during compilation. In addition, if
+                <filename>sd-daemon.c</filename> is compiled on
+                non-Linux systems they become NOPs, too.</para>
+        </refsect1>
+
+        <refsect1>
+                <title>See Also</title>
+                <para>
+                        <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>sd_booted</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>sd_is_fifo</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>fprintf</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+                </para>
+        </refsect1>
+
+</refentry>