153 lines
7.3 KiB
XML
153 lines
7.3 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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This file is part of systemd.
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Copyright 2010 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="sd-daemon">
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<refentryinfo>
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<title>sd-daemon</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>sd-daemon</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>sd-daemon</refname>
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<refname>SD_EMERG</refname>
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<refname>SD_ALERT</refname>
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<refname>SD_CRIT</refname>
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<refname>SD_ERR</refname>
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<refname>SD_WARNING</refname>
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<refname>SD_NOTICE</refname>
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<refname>SD_INFO</refname>
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<refname>SD_DEBUG</refname>
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<refpurpose>APIs for
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new-style daemons</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcsynopsisinfo>#include <systemd/sd-daemon.h></funcsynopsisinfo>
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</funcsynopsis>
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<cmdsynopsis>
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<command>pkg-config --cflags --libs libsystemd</command>
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</cmdsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><filename>sd-daemon.h</filename> provide APIs
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for new-style daemons, as implemented by the
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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init system.</para>
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<para>See
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<citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_booted</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_is_fifo</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_watchdog_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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for more information about the functions
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implemented. In addition to these functions, a couple
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of logging prefixes are defined as macros:</para>
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<programlisting>#define SD_EMERG "<0>" /* system is unusable */
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#define SD_ALERT "<1>" /* action must be taken immediately */
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#define SD_CRIT "<2>" /* critical conditions */
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#define SD_ERR "<3>" /* error conditions */
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#define SD_WARNING "<4>" /* warning conditions */
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#define SD_NOTICE "<5>" /* normal but significant condition */
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#define SD_INFO "<6>" /* informational */
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#define SD_DEBUG "<7>" /* debug-level messages */</programlisting>
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<para>These prefixes are intended to be used in
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conjunction with stderr-based logging as implemented
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by systemd. If a systemd service definition file is
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configured with <varname>StandardError=syslog</varname>
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or <varname>StandardError=kmsg</varname>, these
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prefixes can be used to encode a log level in lines
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printed. This is similar to the kernel
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<function>printk()</function>-style logging. See
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<citerefentry><refentrytitle>klogctl</refentrytitle><manvolnum>2</manvolnum></citerefentry>
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for more information.</para>
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<para>The log levels are identical to
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<citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>'s
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log level system. To use these prefixes simply prefix
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every line with one of these strings. A line that is
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not prefixed will be logged at the default log level
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SD_INFO.</para>
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<example>
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<title>Hello World</title>
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<para>A daemon may log with the log level
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NOTICE by issuing this call:</para>
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<programlisting>fprintf(stderr, SD_NOTICE "Hello World!\n");</programlisting>
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</example>
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</refsect1>
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<refsect1>
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<title>Notes</title>
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<para>These APIs are implemented as a shared library,
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which can be compiled and linked to with the
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<constant>libsystemd</constant> <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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file.</para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_booted</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_is_fifo</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_watchdog_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>fprintf</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd-readahead</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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