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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_print"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>sd_journal_print, sd_journal_printv, sd_journal_send, sd_journal_sendv, sd_journal_perror, SD_JOURNAL_SUPPRESS_LOCATION — Submit log entries 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_print</b>(</code></td><td>int <var class="pdparam">priority</var>, </td></tr><tr><td> </td><td>const char *<var class="pdparam">format</var>, </td></tr><tr><td> </td><td>...<code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><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_printv</b>(</code></td><td>int <var class="pdparam">priority</var>, </td></tr><tr><td> </td><td>const char *<var class="pdparam">format</var>, </td></tr><tr><td> </td><td>va_list <var class="pdparam">ap</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><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_send</b>(</code></td><td>const char *<var class="pdparam">format</var>, </td></tr><tr><td> </td><td>...<code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><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_sendv</b>(</code></td><td>const struct iovec *<var class="pdparam">iov</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">n</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><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_perror</b>(</code></td><td>const char *<var class="pdparam">message</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="idm139822287458016"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description">¶</a></h2><p><code class="function">sd_journal_print()</code> may be used to |
| 23 | submit simple, plain text log entries to the system journal. The | |
| 24 | first argument is a priority value. This is followed by a format | |
| 25 | string and its parameters, similar to | |
| 26 | <a href="http://man7.org/linux/man-pages/man3/printf.3.html"><span class="citerefentry"><span class="refentrytitle">printf</span>(3)</span></a> | |
| 27 | or | |
| 28 | <a href="http://man7.org/linux/man-pages/man3/syslog.3.html"><span class="citerefentry"><span class="refentrytitle">syslog</span>(3)</span></a>. | |
| 29 | The priority value is one of | |
| 30 | <code class="constant">LOG_EMERG</code>, | |
| 31 | <code class="constant">LOG_ALERT</code>, | |
| 32 | <code class="constant">LOG_CRIT</code>, | |
| 33 | <code class="constant">LOG_ERR</code>, | |
| 34 | <code class="constant">LOG_WARNING</code>, | |
| 35 | <code class="constant">LOG_NOTICE</code>, | |
| 36 | <code class="constant">LOG_INFO</code>, | |
| 37 | <code class="constant">LOG_DEBUG</code>, as defined in | |
| 38 | <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. It is recommended to use this call to submit log | |
| 41 | messages in the application locale or system locale and in UTF-8 | |
| 42 | format, but no such restrictions are enforced.</p><p><code class="function">sd_journal_printv()</code> is similar to | |
| 43 | <code class="function">sd_journal_print()</code> but takes a variable | |
| 44 | argument list encapsulated in an object of type | |
| 45 | <code class="varname">va_list</code> (see | |
| 46 | <a href="stdarg.html"><span class="citerefentry"><span class="refentrytitle">stdarg</span>(3)</span></a> | |
| 47 | for more information) instead of the format string. It is | |
| 48 | otherwise equivalent in behavior.</p><p><code class="function">sd_journal_send()</code> may be used to submit | |
| 49 | structured log entries to the system journal. It takes a series of | |
| 50 | format strings, each immediately followed by their associated | |
| 51 | parameters, terminated by <code class="constant">NULL</code>. The strings | |
| 52 | passed should be of the format "<code class="literal">VARIABLE=value</code>". | |
| 53 | The variable name must be in uppercase and consist only of | |
| 54 | characters, numbers and underscores, and may not begin with an | |
| 55 | underscore. (All assignments that do not follow this syntax will | |
| 56 | be ignored.) The value can be of any size and format. It is highly | |
| 57 | recommended to submit text strings formatted in the UTF-8 | |
| 58 | character encoding only, and submit binary fields only when | |
| 59 | formatting in UTF-8 strings is not sensible. A number of well | |
| 60 | known fields are defined, see | |
| 61 | <a href="systemd.journal-fields.html"><span class="citerefentry"><span class="refentrytitle">systemd.journal-fields</span>(7)</span></a> | |
| 62 | for details, but additional application defined fields may be | |
| 63 | used. A variable may be assigned more than one value per | |
| 64 | entry.</p><p><code class="function">sd_journal_sendv()</code> is similar to | |
| 65 | <code class="function">sd_journal_send()</code> but takes an array of | |
| 66 | <code class="varname">struct iovec</code> (as defined in | |
| 67 | <code class="filename">uio.h</code>, see | |
| 68 | <a href="readv.html"><span class="citerefentry"><span class="refentrytitle">readv</span>(3)</span></a> | |
| 69 | for details) instead of the format string. Each structure should | |
| 70 | reference one field of the entry to submit. The second argument | |
| 71 | specifies the number of structures in the array. | |
| 72 | <code class="function">sd_journal_sendv()</code> is particularly useful to | |
| 73 | submit binary objects to the journal where that is | |
| 74 | necessary.</p><p><code class="function">sd_journal_perror()</code> is a similar to | |
| 75 | <a href="perror.html"><span class="citerefentry"><span class="refentrytitle">perror</span>(3)</span></a> | |
| 76 | and writes a message to the journal that consists of the passed | |
| 77 | string, suffixed with ": " and a human readable representation of | |
| 78 | the current error code stored in | |
| 79 | <a href="http://man7.org/linux/man-pages/man3/errno.3.html"><span class="citerefentry"><span class="refentrytitle">errno</span>(3)</span></a>. | |
| 80 | If the message string is passed as <code class="constant">NULL</code> or | |
| 81 | empty string, only the error string representation will be | |
| 82 | written, prefixed with nothing. An additional journal field ERRNO= | |
| 83 | is included in the entry containing the numeric error code | |
| 84 | formatted as decimal string. The log priority used is | |
| 85 | <code class="constant">LOG_ERR</code> (3).</p><p>Note that <code class="function">sd_journal_send()</code> is a | |
| 86 | wrapper around <code class="function">sd_journal_sendv()</code> to make it | |
| 87 | easier to use when only text strings shall be submitted. Also, the | |
| 88 | following two calls are mostly equivalent:</p><pre class="programlisting">sd_journal_print(LOG_INFO, "Hello World, this is PID %lu!", (unsigned long) getpid()); | |
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89 | |
| 90 | sd_journal_send("MESSAGE=Hello World, this is PID %lu!", (unsigned long) getpid(), | |
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91 | "PRIORITY=%i", LOG_INFO, |
| 92 | NULL);</pre><p>Note that these calls implicitly add fields for the source | |
| 93 | file, function name and code line where invoked. This is | |
| 94 | implemented with macros. If this is not desired, it can be turned | |
| 95 | off by defining SD_JOURNAL_SUPPRESS_LOCATION before including | |
| 96 | <code class="filename">sd-journal.h</code>.</p><p><a href="http://man7.org/linux/man-pages/man3/syslog.3.html"><span class="citerefentry"><span class="refentrytitle">syslog</span>(3)</span></a> | |
| 97 | and <code class="function">sd_journal_print()</code> may | |
| 98 | largely be used interchangeably | |
| 99 | functionality-wise. However, note that log messages | |
| 100 | logged via the former take a different path to the | |
| 101 | journal server than the later, and hence global | |
| 102 | chronological ordering between the two streams cannot | |
| 103 | be guaranteed. Using | |
| 104 | <code class="function">sd_journal_print()</code> has the | |
| 105 | benefit of logging source code line, filenames, and | |
| 106 | functions as metadata along all entries, and | |
| 107 | guaranteeing chronological ordering with structured | |
| 108 | log entries that are generated via | |
| 109 | <code class="function">sd_journal_send()</code>. Using | |
| 110 | <code class="function">syslog()</code> has the benefit of being | |
| 111 | more portable.</p></div><div class="refsect1"><a name="idm139822287416560"></a><h2 id="Return Value">Return Value<a class="headerlink" title="Permalink to this headline" href="#Return%20Value">¶</a></h2><p>The four calls return 0 on success or a negative errno-style | |
| 112 | error code. The | |
| 113 | <a href="http://man7.org/linux/man-pages/man3/errno.3.html"><span class="citerefentry"><span class="refentrytitle">errno</span>(3)</span></a> | |
| 114 | variable itself is not altered.</p><p>If | |
| 115 | <a href="systemd-journald.html"><span class="citerefentry"><span class="refentrytitle">systemd-journald</span>(8)</span></a> | |
| 116 | is not running (the socket is not present), those functions do | |
| 117 | nothing, and also return 0.</p></div><div class="refsect1"><a name="idm139822282448320"></a><h2 id="Async signal safety">Async signal safety<a class="headerlink" title="Permalink to this headline" href="#Async%20signal%20safety">¶</a></h2><p><code class="function">sd_journal_sendv()</code> is "async signal | |
| 118 | safe" in the meaning of | |
| 119 | <a href="signal.html"><span class="citerefentry"><span class="refentrytitle">signal</span>(7)</span></a>. | |
| 120 | </p><p><code class="function">sd_journal_print</code>, | |
| 121 | <code class="function">sd_journal_printv</code>, | |
| 122 | <code class="function">sd_journal_send</code>, and | |
| 123 | <code class="function">sd_journal_perror</code> are | |
| 124 | not async signal safe.</p></div><div class="refsect1"><a name="idm139822282443152"></a><h2 id="Notes">Notes<a class="headerlink" title="Permalink to this headline" href="#Notes">¶</a></h2><p>The <code class="function">sd_journal_print()</code>, | |
| 125 | <code class="function">sd_journal_printv()</code>, | |
| 126 | <code class="function">sd_journal_send()</code> and | |
| 127 | <code class="function">sd_journal_sendv()</code> interfaces are available | |
| 128 | as a shared library, which can be compiled and linked to with the | |
| 129 | <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> | |
| 130 | file.</p></div><div class="refsect1"><a name="idm139822282438000"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p> | |
| 131 | <a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>, | |
| 132 | <a href="sd-journal.html"><span class="citerefentry"><span class="refentrytitle">sd-journal</span>(3)</span></a>, | |
| 133 | <a href="sd_journal_stream_fd.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_stream_fd</span>(3)</span></a>, | |
| 134 | <a href="http://man7.org/linux/man-pages/man3/syslog.3.html"><span class="citerefentry"><span class="refentrytitle">syslog</span>(3)</span></a>, | |
| 135 | <a href="perror.html"><span class="citerefentry"><span class="refentrytitle">perror</span>(3)</span></a>, | |
| 136 | <a href="http://man7.org/linux/man-pages/man3/errno.3.html"><span class="citerefentry"><span class="refentrytitle">errno</span>(3)</span></a>, | |
| 137 | <a href="systemd.journal-fields.html"><span class="citerefentry"><span class="refentrytitle">systemd.journal-fields</span>(7)</span></a>, | |
| 138 | <a href="signal.html"><span class="citerefentry"><span class="refentrytitle">signal</span>(7)</span></a>, | |
| 139 | <a href="socket.html"><span class="citerefentry"><span class="refentrytitle">socket</span>(7)</span></a> | |
| 140 | </p></div></div></body></html> |