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<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>sd_journal_get_cursor</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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<a href="../libudev/index.html">gudev </a><span style="float:right">systemd 208</span><hr><div class="refentry"><a name="sd_journal_get_cursor"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>sd_journal_get_cursor, sd_journal_test_cursor — Get cursor string for or test cursor string against the current journal entry</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_get_cursor</b>(</code></td><td>sd_journal* <var class="pdparam">j</var>, </td></tr><tr><td> </td><td>char ** <var class="pdparam">cursor</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_test_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="idm274677906448"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description">¶</a></h2><p><code class="function">sd_journal_get_cursor()</code>
returns a cursor string for the current journal
entry. A cursor is a serialization of the current
journal position formatted as text. The string only
contains printable characters and can be passed around
in text form. The cursor identifies a journal entry
globally and in a stable way and may be used to later
seek to it via
<a href="sd_journal_seek_cursor.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_seek_cursor</span>(3)</span></a>. The
cursor string should be considered opaque and not be
parsed by clients. Seeking to a cursor position
without the specific entry being available locally
will seek to the next closest (in terms of time)
available entry. The call takes two arguments: a
journal context object and a pointer to a string
pointer where the cursor string will be placed. The
string is allocated via libc
<a href="malloc.html"><span class="citerefentry"><span class="refentrytitle">malloc</span>(3)</span></a>
and should be freed after use with
<a href="free.html"><span class="citerefentry"><span class="refentrytitle">free</span>(3)</span></a>.</p><p>Note that
<code class="function">sd_journal_get_cursor()</code> will not
work before
<a href="sd_journal_next.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_next</span>(3)</span></a>
(or related call) has been called at least once, in
order to position the read pointer at a valid
entry.</p><p><code class="function">sd_journal_test_cursor()</code>
may be used to check whether the current position in
the journal matches the specified cursor. This is
useful since cursor strings do not uniquely identify
an entry: the same entry might be referred to by
multiple different cursor strings, and hence string
comparing cursors is not possible. Use this call to
verify after an invocation of
<a href="sd_journal_seek_cursor.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_seek_cursor</span>(3)</span></a>
whether the entry being sought to was actually found
in the journal or the next closest entry was used
instead.</p></div><div class="refsect1"><a name="idm274677896256"></a><h2 id="Return Value">Return Value<a class="headerlink" title="Permalink to this headline" href="#Return%20Value">¶</a></h2><p><code class="function">sd_journal_get_cursor()</code>
returns 0 on success or a negative errno-style error
code. <code class="function">sd_journal_test_cursor()</code>
returns positive if the current entry matches the
specified cursor, 0 if it does not match the specified
cursor or a negative errno-style error code on
failure.</p></div><div class="refsect1"><a name="idm274677893456"></a><h2 id="Notes">Notes<a class="headerlink" title="Permalink to this headline" href="#Notes">¶</a></h2><p>The <code class="function">sd_journal_get_cursor()</code>
and <code class="function">sd_journal_test_cursor()</code>
interfaces are available as shared library, which can
be compiled and linked to with the
<code class="constant">libsystemd-journal</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="idm274681605664"></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_open.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_open</span>(3)</span></a>,
<a href="sd_journal_seek_cursor.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_seek_cursor</span>(3)</span></a>
</p></div></div></body></html>
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