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1 | <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 V1.78.1"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><style> |
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22 | <a href="../libudev/index.html">gudev </a><span style="float:right">systemd 217</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 |
| 23 | 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="idm214188285792"></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> | |
| 663996b3 | 24 | seeks to the beginning of the journal, i.e. the oldest |
| 60f067b4 | 25 | available entry.</p><p>Similarly, |
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26 | <code class="function">sd_journal_seek_tail()</code> may be |
| 27 | used to seek to the end of the journal, i.e. the most | |
| 28 | recent available entry.</p><p><code class="function">sd_journal_seek_monotonic_usec()</code> | |
| 29 | seeks to the entry with the specified monotonic | |
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30 | timestamp, |
| 31 | i.e. <code class="constant">CLOCK_MONOTONIC</code>. Since | |
| 32 | monotonic time restarts on every reboot a boot ID | |
| 33 | needs to be specified as well.</p><p><code class="function">sd_journal_seek_realtime_usec()</code> | |
| 663996b3 | 34 | seeks to the entry with the specified realtime |
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35 | (wallclock) timestamp, |
| 36 | i.e. <code class="constant">CLOCK_REALTIME</code>. Note that | |
| 663996b3 | 37 | the realtime clock is not necessarily monotonic. If a |
| 14228c0d | 38 | realtime timestamp is ambiguous, it is not defined |
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39 | which position is sought to.</p><p><code class="function">sd_journal_seek_cursor()</code> |
| 40 | seeks to the entry located at the specified cursor | |
| 14228c0d | 41 | string. For details on cursors, see |
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42 | <a href="sd_journal_get_cursor.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_get_cursor</span>(3)</span></a>. If |
| 43 | no entry matching the specified cursor is found the | |
| 44 | call will seek to the next closest entry (in terms of | |
| 45 | time) instead. To verify whether the newly selected | |
| 14228c0d | 46 | entry actually matches the cursor, use |
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47 | <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 |
| 48 | entry the new current entry, this needs to be done in | |
| 49 | a separate step with a subsequent | |
| 50 | <a href="sd_journal_next.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_next</span>(3)</span></a> | |
| 14228c0d | 51 | invocation (or a similar call). Only then, entry data |
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52 | may be retrieved via |
| 53 | <a href="sd_journal_get_data.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_get_data</span>(3)</span></a>. If | |
| 54 | no entry exists that matches exactly the specified | |
| 14228c0d | 55 | seek address, the next closest is sought to. If |
| 663996b3 | 56 | <a href="sd_journal_next.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_next</span>(3)</span></a> |
| 14228c0d | 57 | is used, the closest following entry will be sought to, |
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58 | if |
| 59 | <a href="sd_journal_previous.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_previous</span>(3)</span></a> | |
| 60 | is used the closest preceding entry is sought | |
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61 | to.</p></div><div class="refsect1"><a name="idm214188272048"></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 |
| 62 | errno-style error code.</p></div><div class="refsect1"><a name="idm214188263536"></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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63 | <code class="function">sd_journal_seek_tail()</code>, |
| 64 | <code class="function">sd_journal_seek_monotonic_usec()</code>, | |
| 65 | <code class="function">sd_journal_seek_realtime_usec()</code>, | |
| 66 | and <code class="function">sd_journal_seek_cursor()</code> | |
| 60f067b4 | 67 | interfaces are available as a shared library, which can |
| 663996b3 | 68 | be compiled and linked to with the |
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69 | <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> |
| 70 | file.</p></div><div class="refsect1"><a name="idm214188256944"></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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71 | <a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>, |
| 72 | <a href="sd-journal.html"><span class="citerefentry"><span class="refentrytitle">sd-journal</span>(3)</span></a>, | |
| 73 | <a href="sd_journal_open.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_open</span>(3)</span></a>, | |
| 74 | <a href="sd_journal_next.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_next</span>(3)</span></a>, | |
| 75 | <a href="sd_journal_get_data.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_get_data</span>(3)</span></a>, | |
| 76 | <a href="sd_journal_get_cursor.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_get_cursor</span>(3)</span></a>, | |
| 77 | <a href="sd_journal_get_realtime_usec.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_get_realtime_usec</span>(3)</span></a> | |
| 78 | </p></div></div></body></html> |