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22 | <a href="../libudev/index.html">gudev </a><span style="float:right">systemd 219</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="idm139881645423328"></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 |
| 23 | create a log stream file descriptor. Log messages written to this | |
| 24 | file descriptor as simple newline-separated text strings are | |
| 25 | written to the journal. This file descriptor can be used | |
| 26 | internally by applications or be made standard output or standard | |
| 27 | error of other processes executed.</p><p><code class="function">sd_journal_stream_fd()</code> takes a short | |
| 28 | program identifier string as first argument, which will be written | |
| 29 | to the journal as _SYSLOG_IDENTIFIER= field for each log entry | |
| 30 | (see | |
| 31 | <a href="systemd.journal-fields.html"><span class="citerefentry"><span class="refentrytitle">systemd.journal-fields</span>(7)</span></a> | |
| 32 | for more information). The second argument shall be the default | |
| 33 | priority level for all messages. The priority level is one of | |
| 34 | <code class="constant">LOG_EMERG</code>, <code class="constant">LOG_ALERT</code>, | |
| 35 | <code class="constant">LOG_CRIT</code>, <code class="constant">LOG_ERR</code>, | |
| 36 | <code class="constant">LOG_WARNING</code>, <code class="constant">LOG_NOTICE</code>, | |
| 37 | <code class="constant">LOG_INFO</code>, <code class="constant">LOG_DEBUG</code>, as | |
| 38 | defined in <code class="filename">syslog.h</code>, see | |
| 39 | <a href="http://man7.org/linux/man-pages/man3/syslog.3.html"><span class="citerefentry"><span class="refentrytitle">syslog</span>(3)</span></a> | |
| 40 | for details. The third argument is a boolean: if true kernel-style | |
| 41 | log level prefixes (such as <code class="constant">SD_WARNING</code>) are | |
| 42 | interpreted, see | |
| 43 | <a href="sd-daemon.html"><span class="citerefentry"><span class="refentrytitle">sd-daemon</span>(3)</span></a> | |
| 44 | for more information.</p><p>It is recommended that applications log UTF-8 messages only | |
| 45 | with this API, but this is not enforced.</p></div><div class="refsect1"><a name="idm139881649310304"></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 | |
| 46 | success or a negative errno-style error code.</p></div><div class="refsect1"><a name="idm139881649308992"></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 | |
| 47 | available as a shared library, which can be compiled and linked to | |
| 48 | with the | |
| 49 | <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> | |
| 50 | file.</p></div><div class="refsect1"><a name="idm139881649305376"></a><h2 id="Examples">Examples<a class="headerlink" title="Permalink to this headline" href="#Examples">¶</a></h2><p>Creating a log stream suitable for | |
| 51 | <a href="http://man7.org/linux/man-pages/man3/fprintf.3.html"><span class="citerefentry"><span class="refentrytitle">fprintf</span>(3)</span></a>:</p><pre class="programlisting">#include <syslog.h> | |
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52 | #include <stdio.h> |
| 53 | #include <string.h> | |
| 54 | #include <unistd.h> | |
| 55 | #include <systemd/sd-journal.h> | |
| 56 | #include <systemd/sd-daemon.h> | |
| 57 | ||
| 58 | int main(int argc, char *argv[]) { | |
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59 | int fd; |
| 60 | FILE *log; | |
| 61 | fd = sd_journal_stream_fd("test", LOG_INFO, 1); | |
| 62 | if (fd < 0) { | |
| 63 | fprintf(stderr, "Failed to create stream fd: %s\n", strerror(-fd)); | |
| 64 | return 1; | |
| 65 | } | |
| 66 | log = fdopen(fd, "w"); | |
| 67 | if (!log) { | |
| 68 | fprintf(stderr, "Failed to create file object: %m\n"); | |
| 69 | close(fd); | |
| 70 | return 1; | |
| 71 | } | |
| 72 | fprintf(log, "Hello World!\n"); | |
| 73 | fprintf(log, SD_WARNING "This is a warning!\n"); | |
| 74 | fclose(log); | |
| 75 | return 0; | |
| 76 | }</pre></div><div class="refsect1"><a name="idm139881649300656"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p> | |
| 77 | <a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>, | |
| 78 | <a href="sd-journal.html"><span class="citerefentry"><span class="refentrytitle">sd-journal</span>(3)</span></a>, | |
| 79 | <a href="sd-daemon.html"><span class="citerefentry"><span class="refentrytitle">sd-daemon</span>(3)</span></a>, | |
| 80 | <a href="sd_journal_print.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_print</span>(3)</span></a>, | |
| 81 | <a href="http://man7.org/linux/man-pages/man3/syslog.3.html"><span class="citerefentry"><span class="refentrytitle">syslog</span>(3)</span></a>, | |
| 82 | <a href="http://man7.org/linux/man-pages/man3/fprintf.3.html"><span class="citerefentry"><span class="refentrytitle">fprintf</span>(3)</span></a>, | |
| 83 | <a href="systemd.journal-fields.html"><span class="citerefentry"><span class="refentrytitle">systemd.journal-fields</span>(7)</span></a> | |
| 84 | </p></div></div></body></html> |