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14228c0d | 22 | <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> |
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23 | returns a cursor string for the current journal |
24 | entry. A cursor is a serialization of the current | |
25 | journal position formatted as text. The string only | |
26 | contains printable characters and can be passed around | |
27 | in text form. The cursor identifies a journal entry | |
28 | globally and in a stable way and may be used to later | |
29 | seek to it via | |
30 | <a href="sd_journal_seek_cursor.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_seek_cursor</span>(3)</span></a>. The | |
31 | cursor string should be considered opaque and not be | |
32 | parsed by clients. Seeking to a cursor position | |
33 | without the specific entry being available locally | |
34 | will seek to the next closest (in terms of time) | |
35 | available entry. The call takes two arguments: a | |
36 | journal context object and a pointer to a string | |
37 | pointer where the cursor string will be placed. The | |
38 | string is allocated via libc | |
39 | <a href="malloc.html"><span class="citerefentry"><span class="refentrytitle">malloc</span>(3)</span></a> | |
40 | and should be freed after use with | |
41 | <a href="free.html"><span class="citerefentry"><span class="refentrytitle">free</span>(3)</span></a>.</p><p>Note that | |
42 | <code class="function">sd_journal_get_cursor()</code> will not | |
43 | work before | |
44 | <a href="sd_journal_next.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_next</span>(3)</span></a> | |
45 | (or related call) has been called at least once, in | |
46 | order to position the read pointer at a valid | |
47 | entry.</p><p><code class="function">sd_journal_test_cursor()</code> | |
48 | may be used to check whether the current position in | |
49 | the journal matches the specified cursor. This is | |
50 | useful since cursor strings do not uniquely identify | |
51 | an entry: the same entry might be referred to by | |
52 | multiple different cursor strings, and hence string | |
53 | comparing cursors is not possible. Use this call to | |
54 | verify after an invocation of | |
55 | <a href="sd_journal_seek_cursor.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_seek_cursor</span>(3)</span></a> | |
56 | whether the entry being sought to was actually found | |
57 | in the journal or the next closest entry was used | |
14228c0d | 58 | 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> |
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59 | returns 0 on success or a negative errno-style error |
60 | code. <code class="function">sd_journal_test_cursor()</code> | |
61 | returns positive if the current entry matches the | |
14228c0d | 62 | specified cursor, 0 if it does not match the specified |
663996b3 | 63 | cursor or a negative errno-style error code on |
14228c0d | 64 | 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> |
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65 | and <code class="function">sd_journal_test_cursor()</code> |
66 | interfaces are available as shared library, which can | |
67 | be compiled and linked to with the | |
14228c0d MB |
68 | <code class="constant">libsystemd-journal</code> <a href="pkg-config.html"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a> |
69 | 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> | |
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70 | <a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>, |
71 | <a href="sd-journal.html"><span class="citerefentry"><span class="refentrytitle">sd-journal</span>(3)</span></a>, | |
72 | <a href="sd_journal_open.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_open</span>(3)</span></a>, | |
73 | <a href="sd_journal_seek_cursor.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_seek_cursor</span>(3)</span></a> | |
74 | </p></div></div></body></html> |