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<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>sd_journal_seek_head</title><meta name="generator" content="DocBook XSL Stylesheets V1.77.1"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><a href="index.html">Index </a>·
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<a href="../libudev/index.html">gudev </a><span style="float:right">systemd 202</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="idp57024"></a><h2>Description</h2><p><code class="function">sd_journal_seek_head()</code>
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seeks to the beginning of the journal, i.e. the oldest
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available entry.</p><p>Similar,
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<code class="function">sd_journal_seek_tail()</code> may be
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used to seek to the end of the journal, i.e. the most
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recent available entry.</p><p><code class="function">sd_journal_seek_monotonic_usec()</code>
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seeks to the entry with the specified monotonic
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timestamp, i.e. CLOCK_MONOTONIC. Since monotonic time
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restarts on every reboot a boot ID needs to be
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specified as well.</p><p><code class="function">sd_journal_seek_realtime_usec()</code>
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seeks to the entry with the specified realtime
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(wallclock) timestamp, i.e. CLOCK_REALTIME. Note that
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the realtime clock is not necessarily monotonic. If a
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realtime timestamp is ambiguous it is not defined
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which position is sought to.</p><p><code class="function">sd_journal_seek_cursor()</code>
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seeks to the entry located at the specified cursor
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string. For details on 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>. If
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no entry matching the specified cursor is found the
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call will seek to the next closest entry (in terms of
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time) instead. To verify whether the newly selected
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entry actually matches the 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
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entry the new current entry, this needs to be done in
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a separate step with a 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
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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>. If
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no entry exists that matches exactly the specified
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seek 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,
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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
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to.</p></div><div class="refsect1"><a name="idp69872"></a><h2>Return Value</h2><p>The functions return 0 on success or a negative
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errno-style error code.</p></div><div class="refsect1"><a name="idp71056"></a><h2>Notes</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 shared library, which can
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be compiled and linked to with the
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<code class="literal">libsystemd-journal</code>
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<a href="pkg-config.html"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a>
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file.</p></div><div class="refsect1"><a name="idp109360"></a><h2>See Also</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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