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<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>sd_journal_stream_fd</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 215</span><hr><div class="refentry"><a name="sd_journal_stream_fd"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>sd_journal_stream_fd — Create log stream file descriptor to the journal</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><pre class="funcsynopsisinfo">#include <systemd/sd-journal.h></pre><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_journal_stream_fd</b>(</code></td><td>const char *<var class="pdparam">identifier</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">priority</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">level_prefix</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="idm214173639024"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description">¶</a></h2><p><code class="function">sd_journal_stream_fd()</code> may
be used to create a log stream file descriptor. Log
messages written to this file descriptor as simple
newline-separated text strings are written to the
journal. This file descriptor can be used internally
by applications or be made standard output or standard
error of other processes executed.</p><p><code class="function">sd_journal_stream_fd()</code>
takes a short program identifier string as first
argument, which will be written to the journal as
_SYSLOG_IDENTIFIER= field for each log entry (see
<a href="systemd.journal-fields.html"><span class="citerefentry"><span class="refentrytitle">systemd.journal-fields</span>(7)</span></a>
for more information). The second argument shall be
the default priority level for all messages. The
priority level is one of <code class="constant">LOG_EMERG</code>,
<code class="constant">LOG_ALERT</code>,
<code class="constant">LOG_CRIT</code>,
<code class="constant">LOG_ERR</code>,
<code class="constant">LOG_WARNING</code>,
<code class="constant">LOG_NOTICE</code>,
<code class="constant">LOG_INFO</code>,
<code class="constant">LOG_DEBUG</code>, as defined in
<code class="filename">syslog.h</code>, see
<a href="syslog.html"><span class="citerefentry"><span class="refentrytitle">syslog</span>(3)</span></a>
for details. The third argument is a boolean: if true
kernel-style log priority level prefixes (such as
<code class="constant">SD_WARNING</code>) are interpreted, see
<a href="sd-daemon.html"><span class="citerefentry"><span class="refentrytitle">sd-daemon</span>(3)</span></a>
for more information.</p><p>It is recommended that applications log UTF-8
messages only with this API, but this is not
enforced.</p></div><div class="refsect1"><a name="idm214173632368"></a><h2 id="Return Value">Return Value<a class="headerlink" title="Permalink to this headline" href="#Return%20Value">¶</a></h2><p>The call returns a valid write-only file descriptor on success or a
negative errno-style error code.</p></div><div class="refsect1"><a name="idm214173631056"></a><h2 id="Notes">Notes<a class="headerlink" title="Permalink to this headline" href="#Notes">¶</a></h2><p>The <code class="function">sd_journal_stream_fd()</code>
interface is available as a shared library, which can
be compiled and linked to with the
<code class="constant">libsystemd</code> <a href="pkg-config.html"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a>
file.</p></div><div class="refsect1"><a name="idm214173627664"></a><h2 id="Examples">Examples<a class="headerlink" title="Permalink to this headline" href="#Examples">¶</a></h2><p>Creating a log stream suitable for
<a href="fprintf.html"><span class="citerefentry"><span class="refentrytitle">fprintf</span>(3)</span></a>:</p><pre class="programlisting">#include <syslog.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <systemd/sd-journal.h>
#include <systemd/sd-daemon.h>
int main(int argc, char *argv[]) {
int fd;
FILE *log;
fd = sd_journal_stream_fd("test", LOG_INFO, 1);
if (fd < 0) {
fprintf(stderr, "Failed to create stream fd: %s\n", strerror(-fd));
return 1;
}
log = fdopen(fd, "w");
if (!log) {
fprintf(stderr, "Failed to create file object: %m\n");
close(fd);
return 1;
}
fprintf(log, "Hello World!\n");
fprintf(log, SD_WARNING "This is a warning!\n");
fclose(log);
return 0;
}</pre></div><div class="refsect1"><a name="idm214173625024"></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-journal.html"><span class="citerefentry"><span class="refentrytitle">sd-journal</span>(3)</span></a>,
<a href="sd-daemon.html"><span class="citerefentry"><span class="refentrytitle">sd-daemon</span>(3)</span></a>,
<a href="sd_journal_print.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_print</span>(3)</span></a>,
<a href="syslog.html"><span class="citerefentry"><span class="refentrytitle">syslog</span>(3)</span></a>,
<a href="fprintf.html"><span class="citerefentry"><span class="refentrytitle">fprintf</span>(3)</span></a>,
<a href="systemd.journal-fields.html"><span class="citerefentry"><span class="refentrytitle">systemd.journal-fields</span>(7)</span></a>
</p></div></div></body></html>
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