<?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 Lesser General Public License as published by the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details. You should have received a copy of the GNU Lesser 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>3</manvolnum> </refmeta> <refnamediv> <refname>sd-daemon</refname> <refname>SD_EMERG</refname> <refname>SD_ALERT</refname> <refname>SD_CRIT</refname> <refname>SD_ERR</refname> <refname>SD_WARNING</refname> <refname>SD_NOTICE</refname> <refname>SD_INFO</refname> <refname>SD_DEBUG</refname> <refpurpose>APIs for new-style daemons</refpurpose> </refnamediv> <refsynopsisdiv> <funcsynopsis> <funcsynopsisinfo>#include <systemd/sd-daemon.h></funcsynopsisinfo> </funcsynopsis> <cmdsynopsis> <command>pkg-config --cflags --libs libsystemd</command> </cmdsynopsis> </refsynopsisdiv> <refsect1> <title>Description</title> <para><filename>sd-daemon.h</filename> provide APIs for new-style daemons, as implemented by the <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</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>, <citerefentry><refentrytitle>sd_watchdog_enabled</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 "<0>" /* system is unusable */ #define SD_ALERT "<1>" /* action must be taken immediately */ #define SD_CRIT "<2>" /* critical conditions */ #define SD_ERR "<3>" /* error conditions */ #define SD_WARNING "<4>" /* warning conditions */ #define SD_NOTICE "<5>" /* normal but significant condition */ #define SD_INFO "<6>" /* informational */ #define SD_DEBUG "<7>" /* 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 APIs are implemented as a shared library, which can be compiled and linked to with the <constant>libsystemd</constant> <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> file.</para> </refsect1> <refsect1> <title>See Also</title> <para> <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, <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>sd_watchdog_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>, <citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</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>, <citerefentry><refentrytitle>sd-readahead</refentrytitle><manvolnum>3</manvolnum></citerefentry>, <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> </para> </refsect1> </refentry>