man/SD_JOURNAL_SYSTEM_ONLY.html

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  22   <a href="../libudev/index.html">gudev </a><span style="float:right">systemd 204</span><hr><div class="refentry"><a name="sd_journal_open"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>sd_journal_open, sd_journal_open_directory, sd_journal_close, sd_journal, SD_JOURNAL_LOCAL_ONLY, SD_JOURNAL_RUNTIME_ONLY, SD_JOURNAL_SYSTEM_ONLY — Open the system journal for reading</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_open</b>(</code></td><td>sd_journal** <var class="pdparam">ret</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">flags</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_open_directory</b>(</code></td><td>sd_journal** <var class="pdparam">ret</var>, </td></tr><tr><td> </td><td>const char* <var class="pdparam">path</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">flags</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">void <b class="fsfunc">sd_journal_close</b>(</code></td><td>sd_journal* <var class="pdparam">j</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="idm259776818528"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description">¶</a></h2><p><code class="function">sd_journal_open()</code> opens
  23                 the log journal for reading. It will find all journal
  24                 files automatically and interleave them automatically
  25                 when reading. As first argument it takes a pointer to
  26                 a <code class="literal">sd_journal</code> pointer, which on
  27                 success will contain journal context object afterwards. The
  28                 second argument is a flags field, which may consist of
  29                 the following flags ORed together:
  30                 <code class="literal">SD_JOURNAL_LOCAL_ONLY</code> makes sure
  31                 only journal files generated on the local machine will
  32                 be opened. <code class="literal">SD_JOURNAL_RUNTIME_ONLY</code>
  33                 makes sure only volatile journal files will be opened,
  34                 excluding those which are stored on persistent
  35                 storage. <code class="literal">SD_JOURNAL_SYSTEM_ONLY</code>
  36                 will ensure that only journal files of system services
  37                 and the kernel (in opposition to user session processes) will
  38                 be opened.</p><p><code class="function">sd_journal_open_directory()</code>
  39                 is similar to <code class="function">sd_journal_open()</code>
  40                 but takes an absolute directory path as argument. All
  41                 journal files in this directory will be opened and
  42                 interleaved automatically. This call also takes a
  43                 flags argument, but it must be passed as 0 as no flags
  44                 are currently understood for this call.</p><p><code class="function">sd_journal_close()</code> will
  45                 close the journal context allocated with
  46                 <code class="function">sd_journal_open()</code> or
  47                 <code class="function">sd_journal_open_directory()</code> and
  48                 free its resources.</p><p>When opening the journal only journal files
  49                 accessible to the calling user will be opened. If
  50                 journal files are not accessible to the caller this
  51                 will be silently ignored.</p><p>See
  52                 <a href="sd_journal_next.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_next</span>(3)</span></a>
  53                 for an example how to iterate through the journal
  54                 after opening it with
  55                 <code class="function">sd_journal_open()</code>.</p><p>A journal context object returned by
  56                 <code class="function">sd_journal_open()</code> references a
  57                 specific journal entry as <span class="emphasis"><em>current</em></span> entry,
  58                 similar to a file seek index in a classic file system
  59                 file, but without absolute positions. It may be
  60                 altered with
  61                 <a href="sd_journal_next.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_next</span>(3)</span></a>
  62                 and
  63                 <a href="sd_journal_seek_head.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_seek_head</span>(3)</span></a>
  64                 and related calls. The current entry position may be
  65                 exported in <span class="emphasis"><em>cursor</em></span> strings, as accessible
  66                 via
  67                 <a href="sd_journal_get_cursor.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_get_cursor</span>(3)</span></a>. Cursor
  68                 strings may be used to globally identify a specific
  69                 journal entry in a stable way and then later to seek
  70                 to it (or if the specific entry is not available
  71                 locally, to its closest entry in time)
  72                 <a href="sd_journal_seek_cursor.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_seek_cursor</span>(3)</span></a>.</p><p>Notification of journal changes is available via
  73                 <code class="function">sd_journal_get_fd()</code> and related
  74                 calls.</p></div><div class="refsect1"><a name="idm259780692640"></a><h2 id="Return Value">Return Value<a class="headerlink" title="Permalink to this headline" href="#Return%20Value">¶</a></h2><p>The <code class="function">sd_journal_open()</code> and
  75                 <code class="function">sd_journal_open_directory()</code> calls
  76                 return 0 on success or a negative errno-style error
  77                 code. <code class="function">sd_journal_close()</code> returns
  78                 nothing.</p></div><div class="refsect1"><a name="idm259780689152"></a><h2 id="Notes">Notes<a class="headerlink" title="Permalink to this headline" href="#Notes">¶</a></h2><p>The <code class="function">sd_journal_open()</code>,
  79                 <code class="function">sd_journal_open_directory()</code> and
  80                 <code class="function">sd_journal_close()</code> interfaces are
  81                 available as shared library, which can be compiled and
  82                 linked to with the
  83                 <code class="literal">libsystemd-journal</code>
  84                 <a href="pkg-config.html"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a>
  85                 file.</p></div><div class="refsect1"><a name="idm259780684064"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p>
  86                         <a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>,
  87                         <a href="sd-journal.html"><span class="citerefentry"><span class="refentrytitle">sd-journal</span>(3)</span></a>,
  88                         <a href="sd_journal_next.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_next</span>(3)</span></a>,
  89                         <a href="sd_journal_get_data.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_get_data</span>(3)</span></a>
  90                 </p></div></div></body></html>