mirror of
https://github.com/systemd/systemd
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4bc96dc162
Before libsystemd-daemon, libsystemd-journal, libsystemd-id128, etc., were merged into libsystemd, it was enough to have individual man pages for them. But they have been delivered as one thing for many years, so it's better to have a landing page for libsystemd. It mostly directs to individual pages anyway.
115 lines
5.1 KiB
XML
115 lines
5.1 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
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<refentry id="sd-daemon"
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xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>sd-daemon</title>
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<productname>systemd</productname>
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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> is part of
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<citerefentry><refentrytitle>libsystemd</refentrytitle><manvolnum>3</manvolnum></citerefentry> and
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provides APIs for new-style daemons, as implemented by the
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry> service
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manager.</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 implemented. In addition
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to these functions, a couple of logging prefixes are defined as
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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 conjunction with stderr-based logging (or stdout-based
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logging) as implemented by systemd. If a systemd service definition file is configured with
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<varname>StandardError=journal</varname> or <varname>StandardError=kmsg</varname> (and similar with
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<varname>StandardOutput=</varname>), these prefixes can be used to encode a log level in lines
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printed. This is similar to the kernel <function>printk()</function>-style logging. See
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<citerefentry><refentrytitle>klogctl</refentrytitle><manvolnum>2</manvolnum></citerefentry> for more
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information.</para>
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<para>The log levels are identical to
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<citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>'s
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log level system. To use these prefixes simply prefix every line
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with one of these strings. A line that is not prefixed will be
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logged at the default log level 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 NOTICE by issuing this
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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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<xi:include href="libsystemd-pkgconfig.xml" />
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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 project='man-pages'><refentrytitle>fprintf</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry project='die-net'><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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