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<a href="../libudev/index.html">gudev </a><span style="float:right">systemd 219</span><hr><div class="refentry"><a name="sd_journal_seek_head"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>sd_journal_seek_head, sd_journal_seek_tail, sd_journal_seek_monotonic_usec, sd_journal_seek_realtime_usec, sd_journal_seek_cursor — Seek to a position in the
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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_seek_head</b>(</code></td><td>sd_journal *<var class="pdparam">j</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_seek_tail</b>(</code></td><td>sd_journal *<var class="pdparam">j</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_seek_monotonic_usec</b>(</code></td><td>sd_journal *<var class="pdparam">j</var>, </td></tr><tr><td> </td><td>sd_id128_t <var class="pdparam">boot_id</var>, </td></tr><tr><td> </td><td>uint64_t <var class="pdparam">usec</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_seek_realtime_usec</b>(</code></td><td>sd_journal *<var class="pdparam">j</var>, </td></tr><tr><td> </td><td>uint64_t <var class="pdparam">usec</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_seek_cursor</b>(</code></td><td>sd_journal *<var class="pdparam">j</var>, </td></tr><tr><td> </td><td>const char *<var class="pdparam">cursor</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="idm140582072542464"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description">¶</a></h2><p><code class="function">sd_journal_seek_head()</code> seeks to the
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beginning of the journal, i.e. the oldest available entry.</p><p>Similarly, <code class="function">sd_journal_seek_tail()</code> may
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be used to seek to the end of the journal, i.e. the most recent
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available entry.</p><p><code class="function">sd_journal_seek_monotonic_usec()</code> seeks
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to the entry with the specified monotonic timestamp, i.e.
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<code class="constant">CLOCK_MONOTONIC</code>. Since monotonic time
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restarts on every reboot a boot ID needs to be specified as
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well.</p><p><code class="function">sd_journal_seek_realtime_usec()</code> seeks
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to the entry with the specified realtime (wallclock) timestamp,
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i.e. <code class="constant">CLOCK_REALTIME</code>. Note that the realtime
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clock is not necessarily monotonic. If a realtime timestamp is
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ambiguous, it is not defined which position is sought to.</p><p><code class="function">sd_journal_seek_cursor()</code> seeks to the
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entry located at the specified cursor string. For details on
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cursors, see
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<a href="sd_journal_get_cursor.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_get_cursor</span>(3)</span></a>.
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If no entry matching the specified cursor is found the call will
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seek to the next closest entry (in terms of time) instead. To
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verify whether the newly selected entry actually matches the
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cursor, use
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<a href="sd_journal_test_cursor.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_test_cursor</span>(3)</span></a>.</p><p>Note that these calls do not actually make any entry the new
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current entry, this needs to be done in a separate step with a
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subsequent
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<a href="sd_journal_next.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_next</span>(3)</span></a>
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invocation (or a similar call). Only then, entry data may be
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retrieved via
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<a href="sd_journal_get_data.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_get_data</span>(3)</span></a>.
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If no entry exists that matches exactly the specified seek
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address, the next closest is sought to. If
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<a href="sd_journal_next.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_next</span>(3)</span></a>
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is used, the closest following entry will be sought to, if
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<a href="sd_journal_previous.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_previous</span>(3)</span></a>
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is used the closest preceding entry is sought to.</p></div><div class="refsect1"><a name="idm140582072529568"></a><h2 id="Return Value">Return Value<a class="headerlink" title="Permalink to this headline" href="#Return%20Value">¶</a></h2><p>The functions return 0 on success or a negative errno-style
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error code.</p></div><div class="refsect1"><a name="idm140582072528384"></a><h2 id="Notes">Notes<a class="headerlink" title="Permalink to this headline" href="#Notes">¶</a></h2><p>The <code class="function">sd_journal_seek_head()</code>,
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<code class="function">sd_journal_seek_tail()</code>,
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<code class="function">sd_journal_seek_monotonic_usec()</code>,
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<code class="function">sd_journal_seek_realtime_usec()</code>,
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and <code class="function">sd_journal_seek_cursor()</code>
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interfaces are available as a shared library, which can
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be compiled and linked to with the
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<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>
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file.</p></div><div class="refsect1"><a name="idm140582072514352"></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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<a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>,
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<a href="sd-journal.html"><span class="citerefentry"><span class="refentrytitle">sd-journal</span>(3)</span></a>,
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<a href="sd_journal_open.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_open</span>(3)</span></a>,
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<a href="sd_journal_next.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_next</span>(3)</span></a>,
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<a href="sd_journal_get_data.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_get_data</span>(3)</span></a>,
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<a href="sd_journal_get_cursor.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_get_cursor</span>(3)</span></a>,
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<a href="sd_journal_get_realtime_usec.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_get_realtime_usec</span>(3)</span></a>
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</p></div></div></body></html>
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