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<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>sd_journal_print</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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<span style="float:right">systemd 221</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="idm47607359182800"></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
submit simple, plain text log entries to the system journal. The
first argument is a priority value. This is followed by a format
string and its parameters, similar to
<a href="http://man7.org/linux/man-pages/man3/printf.3.html"><span class="citerefentry"><span class="refentrytitle">printf</span>(3)</span></a>
or
<a href="http://man7.org/linux/man-pages/man3/syslog.3.html"><span class="citerefentry"><span class="refentrytitle">syslog</span>(3)</span></a>.
The priority value 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="http://man7.org/linux/man-pages/man3/syslog.3.html"><span class="citerefentry"><span class="refentrytitle">syslog</span>(3)</span></a>
for details. It is recommended to use this call to submit log
messages in the application locale or system locale and in UTF-8
format, but no such restrictions are enforced.</p><p><code class="function">sd_journal_printv()</code> is similar to
<code class="function">sd_journal_print()</code> but takes a variable
argument list encapsulated in an object of type
<code class="varname">va_list</code> (see
<a href="http://man7.org/linux/man-pages/man3/stdarg.3.html"><span class="citerefentry"><span class="refentrytitle">stdarg</span>(3)</span></a>
for more information) instead of the format string. It is
otherwise equivalent in behavior.</p><p><code class="function">sd_journal_send()</code> may be used to submit
structured log entries to the system journal. It takes a series of
format strings, each immediately followed by their associated
parameters, terminated by <code class="constant">NULL</code>. The strings
passed should be of the format "<code class="literal">VARIABLE=value</code>".
The variable name must be in uppercase and consist only of
characters, numbers and underscores, and may not begin with an
underscore. (All assignments that do not follow this syntax will
be ignored.) The value can be of any size and format. It is highly
recommended to submit text strings formatted in the UTF-8
character encoding only, and submit binary fields only when
formatting in UTF-8 strings is not sensible. A number of well
known fields are defined, see
<a href="systemd.journal-fields.html"><span class="citerefentry"><span class="refentrytitle">systemd.journal-fields</span>(7)</span></a>
for details, but additional application defined fields may be
used. A variable may be assigned more than one value per
entry.</p><p><code class="function">sd_journal_sendv()</code> is similar to
<code class="function">sd_journal_send()</code> but takes an array of
<code class="varname">struct iovec</code> (as defined in
<code class="filename">uio.h</code>, see
<a href="http://man7.org/linux/man-pages/man3/readv.3.html"><span class="citerefentry"><span class="refentrytitle">readv</span>(3)</span></a>
for details) instead of the format string. Each structure should
reference one field of the entry to submit. The second argument
specifies the number of structures in the array.
<code class="function">sd_journal_sendv()</code> is particularly useful to
submit binary objects to the journal where that is
necessary.</p><p><code class="function">sd_journal_perror()</code> is a similar to
<a href="http://linux.die.net/man/3/perror"><span class="citerefentry"><span class="refentrytitle">perror</span>(3)</span></a>
and writes a message to the journal that consists of the passed
string, suffixed with ": " and a human readable representation of
the current error code stored in
<a href="http://man7.org/linux/man-pages/man3/errno.3.html"><span class="citerefentry"><span class="refentrytitle">errno</span>(3)</span></a>.
If the message string is passed as <code class="constant">NULL</code> or
empty string, only the error string representation will be
written, prefixed with nothing. An additional journal field ERRNO=
is included in the entry containing the numeric error code
formatted as decimal string. The log priority used is
<code class="constant">LOG_ERR</code> (3).</p><p>Note that <code class="function">sd_journal_send()</code> is a
wrapper around <code class="function">sd_journal_sendv()</code> to make it
easier to use when only text strings shall be submitted. Also, the
following two calls are mostly equivalent:</p><pre class="programlisting">sd_journal_print(LOG_INFO, "Hello World, this is PID %lu!", (unsigned long) getpid());
sd_journal_send("MESSAGE=Hello World, this is PID %lu!", (unsigned long) getpid(),
"PRIORITY=%i", LOG_INFO,
NULL);</pre><p>Note that these calls implicitly add fields for the source
file, function name and code line where invoked. This is
implemented with macros. If this is not desired, it can be turned
off by defining SD_JOURNAL_SUPPRESS_LOCATION before including
<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>
and <code class="function">sd_journal_print()</code> may
largely be used interchangeably
functionality-wise. However, note that log messages
logged via the former take a different path to the
journal server than the later, and hence global
chronological ordering between the two streams cannot
be guaranteed. Using
<code class="function">sd_journal_print()</code> has the
benefit of logging source code line, filenames, and
functions as metadata along all entries, and
guaranteeing chronological ordering with structured
log entries that are generated via
<code class="function">sd_journal_send()</code>. Using
<code class="function">syslog()</code> has the benefit of being
more portable.</p></div><div class="refsect1"><a name="idm47607359150672"></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
error code. The
<a href="http://man7.org/linux/man-pages/man3/errno.3.html"><span class="citerefentry"><span class="refentrytitle">errno</span>(3)</span></a>
variable itself is not altered.</p><p>If
<a href="systemd-journald.html"><span class="citerefentry"><span class="refentrytitle">systemd-journald</span>(8)</span></a>
is not running (the socket is not present), those functions do
nothing, and also return 0.</p></div><div class="refsect1"><a name="idm47607359147248"></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
safe" in the meaning of
<a href="http://man7.org/linux/man-pages/man7/signal.7.html"><span class="citerefentry"><span class="refentrytitle">signal</span>(7)</span></a>.
</p><p><code class="function">sd_journal_print</code>,
<code class="function">sd_journal_printv</code>,
<code class="function">sd_journal_send</code>, and
<code class="function">sd_journal_perror</code> are
not async signal safe.</p></div><div class="refsect1"><a name="idm47607359141840"></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>,
<code class="function">sd_journal_printv()</code>,
<code class="function">sd_journal_send()</code> and
<code class="function">sd_journal_sendv()</code> interfaces are available
as a shared library, which can be compiled and linked to with the
<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>
file.</p></div><div class="refsect1"><a name="idm47607359136688"></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_journal_stream_fd.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_stream_fd</span>(3)</span></a>,
<a href="http://man7.org/linux/man-pages/man3/syslog.3.html"><span class="citerefentry"><span class="refentrytitle">syslog</span>(3)</span></a>,
<a href="http://linux.die.net/man/3/perror"><span class="citerefentry"><span class="refentrytitle">perror</span>(3)</span></a>,
<a href="http://man7.org/linux/man-pages/man3/errno.3.html"><span class="citerefentry"><span class="refentrytitle">errno</span>(3)</span></a>,
<a href="systemd.journal-fields.html"><span class="citerefentry"><span class="refentrytitle">systemd.journal-fields</span>(7)</span></a>,
<a href="http://man7.org/linux/man-pages/man7/signal.7.html"><span class="citerefentry"><span class="refentrytitle">signal</span>(7)</span></a>,
<a href="http://man7.org/linux/man-pages/man7/socket.7.html"><span class="citerefentry"><span class="refentrytitle">socket</span>(7)</span></a>
</p></div></div></body></html>
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