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| 5eef597e | 22 | <a href="../libudev/index.html">gudev </a><span style="float:right">systemd 217</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="idm214179273248"></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 |
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23 | used to submit simple, plain text log entries to the |
| 24 | system journal. The first argument is a priority | |
| 25 | value. This is followed by a format string and its | |
| 26 | parameters, similar to | |
| 5eef597e | 27 | <a href="http://man7.org/linux/man-pages/man3/printf.3.html"><span class="citerefentry"><span class="refentrytitle">printf</span>(3)</span></a> |
| 663996b3 | 28 | or |
| 5eef597e | 29 | <a href="http://man7.org/linux/man-pages/man3/syslog.3.html"><span class="citerefentry"><span class="refentrytitle">syslog</span>(3)</span></a>. The |
| 663996b3 | 30 | priority value is one of |
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31 | <code class="constant">LOG_EMERG</code>, |
| 32 | <code class="constant">LOG_ALERT</code>, | |
| 33 | <code class="constant">LOG_CRIT</code>, | |
| 34 | <code class="constant">LOG_ERR</code>, | |
| 35 | <code class="constant">LOG_WARNING</code>, | |
| 36 | <code class="constant">LOG_NOTICE</code>, | |
| 37 | <code class="constant">LOG_INFO</code>, | |
| 38 | <code class="constant">LOG_DEBUG</code>, as defined in | |
| 663996b3 | 39 | <code class="filename">syslog.h</code>, see |
| 5eef597e | 40 | <a href="http://man7.org/linux/man-pages/man3/syslog.3.html"><span class="citerefentry"><span class="refentrytitle">syslog</span>(3)</span></a> |
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41 | for details. It is recommended to use this call to |
| 42 | submit log messages in the application locale or system | |
| 43 | locale and in UTF-8 format, but no such restrictions | |
| 44 | are enforced.</p><p><code class="function">sd_journal_printv()</code> is | |
| 45 | similar to <code class="function">sd_journal_print()</code> but | |
| 46 | takes a variable argument list encapsulated in an | |
| 14228c0d | 47 | object of type <code class="varname">va_list</code> (see |
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48 | <a href="stdarg.html"><span class="citerefentry"><span class="refentrytitle">stdarg</span>(3)</span></a> |
| 49 | for more information) instead of the format string. It | |
| 50 | is otherwise equivalent in behavior.</p><p><code class="function">sd_journal_send()</code> may be | |
| 51 | used to submit structured log entries to the system | |
| 52 | journal. It takes a series of format strings, each | |
| 53 | immediately followed by their associated parameters, | |
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54 | terminated by <code class="constant">NULL</code>. The strings passed should be of |
| 55 | the format "<code class="literal">VARIABLE=value</code>". The | |
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56 | variable name must be in uppercase and consist only of |
| 57 | characters, numbers and underscores, and may not begin | |
| 58 | with an underscore. (All assignments that do not | |
| 59 | follow this syntax will be ignored.) The value can be | |
| 60 | of any size and format. It is highly recommended to | |
| 61 | submit text strings formatted in the UTF-8 character | |
| 62 | encoding only, and submit binary fields only when | |
| 14228c0d | 63 | formatting in UTF-8 strings is not sensible. A number |
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64 | of well known fields are defined, see |
| 65 | <a href="systemd.journal-fields.html"><span class="citerefentry"><span class="refentrytitle">systemd.journal-fields</span>(7)</span></a> | |
| 66 | for details, but additional application defined fields | |
| 67 | may be used. A variable may be assigned more than one | |
| 68 | value per entry.</p><p><code class="function">sd_journal_sendv()</code> is | |
| 69 | similar to <code class="function">sd_journal_send()</code> but | |
| 14228c0d | 70 | takes an array of <code class="varname">struct iovec</code> (as |
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71 | defined in <code class="filename">uio.h</code>, see |
| 72 | <a href="readv.html"><span class="citerefentry"><span class="refentrytitle">readv</span>(3)</span></a> | |
| 73 | for details) instead of the format string. Each | |
| 74 | structure should reference one field of the entry to | |
| 75 | submit. The second argument specifies the number of | |
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76 | structures in the array. |
| 77 | <code class="function">sd_journal_sendv()</code> is | |
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78 | particularly useful to submit binary objects to the |
| 79 | journal where that is necessary.</p><p><code class="function">sd_journal_perror()</code> is a | |
| 80 | similar to | |
| 81 | <a href="perror.html"><span class="citerefentry"><span class="refentrytitle">perror</span>(3)</span></a> | |
| 82 | and writes a message to the journal that consists of | |
| 83 | the passed string, suffixed with ": " and a human | |
| 84 | readable representation of the current error code | |
| 85 | stored in | |
| 5eef597e | 86 | <a href="http://man7.org/linux/man-pages/man3/errno.3.html"><span class="citerefentry"><span class="refentrytitle">errno</span>(3)</span></a>. If |
| 14228c0d | 87 | the message string is passed as <code class="constant">NULL</code> or empty string, |
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88 | only the error string representation will be written, |
| 89 | prefixed with nothing. An additional journal field | |
| 90 | ERRNO= is included in the entry containing the numeric | |
| 91 | error code formatted as decimal string. The log | |
| 14228c0d | 92 | priority used is <code class="constant">LOG_ERR</code> (3).</p><p>Note that <code class="function">sd_journal_send()</code> |
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93 | is a wrapper around |
| 94 | <code class="function">sd_journal_sendv()</code> to make it | |
| 95 | easier to use when only text strings shall be | |
| 96 | submitted. Also, the following two calls are | |
| 97 | mostly equivalent:</p><pre class="programlisting">sd_journal_print(LOG_INFO, "Hello World, this is PID %lu!", (unsigned long) getpid()); | |
| 98 | ||
| 99 | sd_journal_send("MESSAGE=Hello World, this is PID %lu!", (unsigned long) getpid(), | |
| 100 | "PRIORITY=%i", LOG_INFO, | |
| 101 | NULL);</pre><p>Note that these calls implicitly add fields for | |
| 102 | the source file, function name and code line where | |
| 103 | invoked. This is implemented with macros. If this is | |
| 14228c0d | 104 | not desired, it can be turned off by defining |
| 663996b3 | 105 | SD_JOURNAL_SUPPRESS_LOCATION before including |
| 5eef597e | 106 | <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> |
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107 | and <code class="function">sd_journal_print()</code> may |
| 108 | largely be used interchangeably | |
| 109 | functionality-wise. However, note that log messages | |
| 110 | logged via the former take a different path to the | |
| 111 | journal server than the later, and hence global | |
| 112 | chronological ordering between the two streams cannot | |
| 113 | be guaranteed. Using | |
| 114 | <code class="function">sd_journal_print()</code> has the | |
| 14228c0d | 115 | benefit of logging source code line, filenames, and |
| 60f067b4 | 116 | functions as metadata along all entries, and |
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117 | guaranteeing chronological ordering with structured |
| 118 | log entries that are generated via | |
| 119 | <code class="function">sd_journal_send()</code>. Using | |
| 120 | <code class="function">syslog()</code> has the benefit of being | |
| 5eef597e | 121 | more portable.</p></div><div class="refsect1"><a name="idm214179230560"></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 |
| 663996b3 | 122 | errno-style error code. The |
| 5eef597e | 123 | <a href="http://man7.org/linux/man-pages/man3/errno.3.html"><span class="citerefentry"><span class="refentrytitle">errno</span>(3)</span></a> |
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124 | variable itself is not altered.</p><p>If |
| 125 | <a href="systemd-journald.html"><span class="citerefentry"><span class="refentrytitle">systemd-journald</span>(8)</span></a> | |
| 126 | is not running (the socket is not present), those | |
| 5eef597e | 127 | functions do nothing, and also return 0.</p></div><div class="refsect1"><a name="idm214174312880"></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 |
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128 | safe" in the meaning of <a href="signal.html"><span class="citerefentry"><span class="refentrytitle">signal</span>(7)</span></a>. |
| 129 | </p><p><code class="function">sd_journal_print</code>, | |
| 130 | <code class="function">sd_journal_printv</code>, | |
| 131 | <code class="function">sd_journal_send</code>, and | |
| 132 | <code class="function">sd_journal_perror</code> are | |
| 5eef597e | 133 | not async signal safe.</p></div><div class="refsect1"><a name="idm214174307824"></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>, |
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134 | <code class="function">sd_journal_printv()</code>, |
| 135 | <code class="function">sd_journal_send()</code> and | |
| 136 | <code class="function">sd_journal_sendv()</code> interfaces | |
| 60f067b4 | 137 | are available as a shared library, which can be compiled |
| 663996b3 | 138 | and linked to with the |
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139 | <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> |
| 140 | file.</p></div><div class="refsect1"><a name="idm214174302624"></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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141 | <a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>, |
| 142 | <a href="sd-journal.html"><span class="citerefentry"><span class="refentrytitle">sd-journal</span>(3)</span></a>, | |
| 143 | <a href="sd_journal_stream_fd.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_stream_fd</span>(3)</span></a>, | |
| 5eef597e | 144 | <a href="http://man7.org/linux/man-pages/man3/syslog.3.html"><span class="citerefentry"><span class="refentrytitle">syslog</span>(3)</span></a>, |
| 663996b3 | 145 | <a href="perror.html"><span class="citerefentry"><span class="refentrytitle">perror</span>(3)</span></a>, |
| 5eef597e | 146 | <a href="http://man7.org/linux/man-pages/man3/errno.3.html"><span class="citerefentry"><span class="refentrytitle">errno</span>(3)</span></a>, |
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147 | <a href="systemd.journal-fields.html"><span class="citerefentry"><span class="refentrytitle">systemd.journal-fields</span>(7)</span></a>, |
| 148 | <a href="signal.html"><span class="citerefentry"><span class="refentrytitle">signal</span>(7)</span></a>, | |
| 149 | <a href="socket.html"><span class="citerefentry"><span class="refentrytitle">socket</span>(7)</span></a> | |
| 663996b3 | 150 | </p></div></div></body></html> |