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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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</style><a href="index.html">Index </a>·
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<a href="../libudev/index.html">gudev </a><span style="float:right">systemd 215</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="idm214193392656"></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="printf.html"><span class="citerefentry"><span class="refentrytitle">printf</span>(3)</span></a>
or
<a href="syslog.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="syslog.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="stdarg.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="readv.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="perror.html"><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="errno.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="syslog.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="idm214193498576"></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="errno.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="idm214193495056"></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="signal.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="idm214193489376"></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="pkg-config.html"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a>
file.</p></div><div class="refsect1"><a name="idm214188855456"></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="syslog.html"><span class="citerefentry"><span class="refentrytitle">syslog</span>(3)</span></a>,
<a href="perror.html"><span class="citerefentry"><span class="refentrytitle">perror</span>(3)</span></a>,
<a href="errno.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="signal.html"><span class="citerefentry"><span class="refentrytitle">signal</span>(7)</span></a>,
<a href="socket.html"><span class="citerefentry"><span class="refentrytitle">socket</span>(7)</span></a>
</p></div></div></body></html>
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