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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_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="idm139955963395968"></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
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cursor string for the current journal entry. A cursor is a
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serialization of the current journal position formatted as text.
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The string only contains printable characters and can be passed
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around in text form. The cursor identifies a journal entry
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globally and in a stable way and may be used to later seek to it
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via
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<a href="sd_journal_seek_cursor.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_seek_cursor</span>(3)</span></a>.
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The cursor string should be considered opaque and not be parsed by
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clients. Seeking to a cursor position without the specific entry
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being available locally will seek to the next closest (in terms of
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time) available entry. The call takes two arguments: a journal
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context object and a pointer to a string pointer where the cursor
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string will be placed. The string is allocated via libc
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<a href="malloc.html"><span class="citerefentry"><span class="refentrytitle">malloc</span>(3)</span></a>
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and should be freed after use with
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<a href="http://man7.org/linux/man-pages/man3/free.3.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
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not work before
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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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(or related call) has been called at least once, in order to
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position the read pointer at a valid entry.</p><p><code class="function">sd_journal_test_cursor()</code>
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may be used to check whether the current position in
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the journal matches the specified cursor. This is
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useful since cursor strings do not uniquely identify
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an entry: the same entry might be referred to by
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multiple different cursor strings, and hence string
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comparing cursors is not possible. Use this call to
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verify after an invocation of
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<a href="sd_journal_seek_cursor.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_seek_cursor</span>(3)</span></a>
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whether the entry being sought to was actually found
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in the journal or the next closest entry was used
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instead.</p></div><div class="refsect1"><a name="idm139955967288928"></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
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success or a negative errno-style error code.
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<code class="function">sd_journal_test_cursor()</code> returns positive if
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the current entry matches the specified cursor, 0 if it does not
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match the specified cursor or a negative errno-style error code on
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failure.</p></div><div class="refsect1"><a name="idm139955967286400"></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
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<code class="function">sd_journal_test_cursor()</code> interfaces are
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available as a shared library, which can be compiled and linked to
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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="idm139955967282032"></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_seek_cursor.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_seek_cursor</span>(3)</span></a>
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</p></div></div></body></html>
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