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<a href="../libudev/index.html">gudev </a><span style="float:right">systemd 208</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="idm274690063392"></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
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be used to create a log stream file descriptor. Log
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messages written to this file descriptor as simple
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newline-separated text strings are written to the
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journal. This file descriptor can be used internally
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by applications or be made STDOUT/STDERR of other
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processes executed.</p><p><code class="function">sd_journal_stream_fd()</code>
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takes a short program identifier string as first
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argument, which will be written to the journal as
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_SYSLOG_IDENTIFIER= field for each log entry (see
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<a href="systemd.journal-fields.html"><span class="citerefentry"><span class="refentrytitle">systemd.journal-fields</span>(7)</span></a>
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for more information). The second argument shall be
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the default priority level for all messages. The
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priority level is one of <code class="constant">LOG_EMERG</code>,
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<code class="constant">LOG_ALERT</code>,
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<code class="constant">LOG_CRIT</code>,
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<code class="constant">LOG_ERR</code>,
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<code class="constant">LOG_WARNING</code>,
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<code class="constant">LOG_NOTICE</code>,
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<code class="constant">LOG_INFO</code>,
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<code class="constant">LOG_DEBUG</code>, as defined in
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<code class="filename">syslog.h</code>, see
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<a href="syslog.html"><span class="citerefentry"><span class="refentrytitle">syslog</span>(3)</span></a>
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for details. The third argument is a boolean: if true
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kernel-style log priority level prefixes (such as
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<code class="constant">SD_WARNING</code>) are interpreted, see
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<a href="sd-daemon.html"><span class="citerefentry"><span class="refentrytitle">sd-daemon</span>(3)</span></a>
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for more information.</p><p>It is recommended that applications log UTF-8
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messages only with this API, but this is not
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enforced.</p></div><div class="refsect1"><a name="idm274693953200"></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
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negative errno-style error code.</p></div><div class="refsect1"><a name="idm274693951888"></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>
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interface is available as shared library, which can
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be compiled and linked to with the
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<code class="constant">libsystemd-journal</code> <a href="pkg-config.html"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a>
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file.</p></div><div class="refsect1"><a name="idm274693948544"></a><h2 id="Examples">Examples<a class="headerlink" title="Permalink to this headline" href="#Examples">¶</a></h2><p>Creating a log stream suitable for
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<a href="fprintf.html"><span class="citerefentry"><span class="refentrytitle">fprintf</span>(3)</span></a>:</p><pre class="programlisting">#include <syslog.h>
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include <systemd/sd-journal.h>
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#include <systemd/sd-daemon.h>
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int main(int argc, char *argv[]) {
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int fd;
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FILE *log;
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fd = sd_journal_stream_fd("test", LOG_INFO, 1);
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if (fd < 0) {
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fprintf(stderr, "Failed to create stream fd: %s\n", strerror(-fd));
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return 1;
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}
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log = fdopen(fd, "w");
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if (!log) {
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fprintf(stderr, "Failed to create file object: %m\n");
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close(fd);
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return 1;
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}
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fprintf(log, "Hello World!\n");
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fprintf(log, SD_WARNING "This is a warning!\n");
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fclose(log);
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return 0;
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}</pre></div><div class="refsect1"><a name="idm274693943824"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p>
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<a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>,
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<a href="sd-journal.html"><span class="citerefentry"><span class="refentrytitle">sd-journal</span>(3)</span></a>,
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<a href="sd-daemon.html"><span class="citerefentry"><span class="refentrytitle">sd-daemon</span>(3)</span></a>,
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<a href="sd_journal_print.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_print</span>(3)</span></a>,
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<a href="syslog.html"><span class="citerefentry"><span class="refentrytitle">syslog</span>(3)</span></a>,
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<a href="fprintf.html"><span class="citerefentry"><span class="refentrytitle">fprintf</span>(3)</span></a>,
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<a href="systemd.journal-fields.html"><span class="citerefentry"><span class="refentrytitle">systemd.journal-fields</span>(7)</span></a>
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</p></div></div></body></html>
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