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<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>sd-daemon</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><style>
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</style><a href="index.html">Index </a>·
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<a href="../libudev/index.html">gudev </a><span style="float:right">systemd 220</span><hr><div class="refentry"><a name="sd-daemon"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>sd-daemon, SD_EMERG, SD_ALERT, SD_CRIT, SD_ERR, SD_WARNING, SD_NOTICE, SD_INFO, SD_DEBUG — APIs for
new-style daemons</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><pre class="funcsynopsisinfo">#include <systemd/sd-daemon.h></pre></div><div class="cmdsynopsis"><p><code class="command">pkg-config --cflags --libs libsystemd</code> </p></div></div><div class="refsect1"><a name="idm139948503956992"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description">¶</a></h2><p><code class="filename">sd-daemon.h</code> provide APIs for new-style
daemons, as implemented by the
<a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>
init system.</p><p>See
<a href="sd_listen_fds.html"><span class="citerefentry"><span class="refentrytitle">sd_listen_fds</span>(3)</span></a>,
<a href="sd_notify.html"><span class="citerefentry"><span class="refentrytitle">sd_notify</span>(3)</span></a>,
<a href="sd_booted.html"><span class="citerefentry"><span class="refentrytitle">sd_booted</span>(3)</span></a>,
<a href="sd_is_fifo.html"><span class="citerefentry"><span class="refentrytitle">sd_is_fifo</span>(3)</span></a>,
<a href="sd_watchdog_enabled.html"><span class="citerefentry"><span class="refentrytitle">sd_watchdog_enabled</span>(3)</span></a>
for more information about the functions implemented. In addition
to these functions, a couple of logging prefixes are defined as
macros:</p><pre class="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 */</pre><p>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
<code class="varname">StandardError=journal</code>,
<code class="varname">StandardError=syslog</code> or
<code class="varname">StandardError=kmsg</code>, these prefixes can be used
to encode a log level in lines printed. This is similar to the
kernel <code class="function">printk()</code>-style logging. See
<a href="http://man7.org/linux/man-pages/man2/klogctl.2.html"><span class="citerefentry"><span class="refentrytitle">klogctl</span>(2)</span></a>
for more information.</p><p>The log levels are identical to
<a href="http://man7.org/linux/man-pages/man3/syslog.3.html"><span class="citerefentry"><span class="refentrytitle">syslog</span>(3)</span></a>'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.</p><div class="example"><a name="idm139948499328720"></a><p class="title"><b>Example 1. Hello World</b></p><div class="example-contents"><p>A daemon may log with the log level NOTICE by issuing this
call:</p><pre class="programlisting">fprintf(stderr, SD_NOTICE "Hello World!\n");</pre></div></div><br class="example-break"></div><div class="refsect1"><a name="idm139948497523952"></a><h2 id="Notes">Notes<a class="headerlink" title="Permalink to this headline" href="#Notes">¶</a></h2><p><a name="pkgconfig-text"></a>These APIs are implemented as a shared
library, which can be compiled and linked to with the
<code class="constant">libsystemd</code> <a href="http://linux.die.net/man/1/pkg-config"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a>
file.</p></div><div class="refsect1"><a name="idm139948499326320"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p>
<a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>,
<a href="sd_listen_fds.html"><span class="citerefentry"><span class="refentrytitle">sd_listen_fds</span>(3)</span></a>,
<a href="sd_notify.html"><span class="citerefentry"><span class="refentrytitle">sd_notify</span>(3)</span></a>,
<a href="sd_booted.html"><span class="citerefentry"><span class="refentrytitle">sd_booted</span>(3)</span></a>,
<a href="sd_is_fifo.html"><span class="citerefentry"><span class="refentrytitle">sd_is_fifo</span>(3)</span></a>,
<a href="sd_watchdog_enabled.html"><span class="citerefentry"><span class="refentrytitle">sd_watchdog_enabled</span>(3)</span></a>,
<a href="daemon.html"><span class="citerefentry"><span class="refentrytitle">daemon</span>(7)</span></a>,
<a href="systemd.service.html"><span class="citerefentry"><span class="refentrytitle">systemd.service</span>(5)</span></a>,
<a href="systemd.socket.html"><span class="citerefentry"><span class="refentrytitle">systemd.socket</span>(5)</span></a>,
<a href="http://man7.org/linux/man-pages/man3/fprintf.3.html"><span class="citerefentry"><span class="refentrytitle">fprintf</span>(3)</span></a>,
<a href="http://linux.die.net/man/1/pkg-config"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a>
</p></div></div></body></html>
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