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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_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 &lt;systemd/sd-journal.h&gt;</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="idm214172116480"></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>
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                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
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                instead.</p></div><div class="refsect1"><a name="idm214172307584"></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>
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                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
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                specified cursor, 0 if it does not match the specified
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                cursor or a negative errno-style error code on
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                failure.</p></div><div class="refsect1"><a name="idm214172304784"></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>
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                and <code class="function">sd_journal_test_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="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="idm214172300656"></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>,
                        <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>