man/sd_journal_open_files.html

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  22   <a href="../libudev/index.html">gudev </a><span style="float:right">systemd 218</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_open_files, sd_journal_open_container, sd_journal_close, sd_journal, SD_JOURNAL_LOCAL_ONLY, SD_JOURNAL_RUNTIME_ONLY, SD_JOURNAL_SYSTEM, SD_JOURNAL_CURRENT_USER — 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">int <b class="fsfunc">sd_journal_open_files</b>(</code></td><td>sd_journal **<var class="pdparam">ret</var>, </td></tr><tr><td> </td><td>const char **<var class="pdparam">paths</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_container</b>(</code></td><td>sd_journal **<var class="pdparam">ret</var>, </td></tr><tr><td> </td><td>const char *<var class="pdparam">machine</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="idm139693584531584"></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="varname">sd_journal</code> pointer, which on
  27                 success will contain a journal context object. The
  28                 second argument is a flags field, which may consist of
  29                 the following flags ORed together:
  30                 <code class="constant">SD_JOURNAL_LOCAL_ONLY</code> makes sure
  31                 only journal files generated on the local machine will
  32                 be opened. <code class="constant">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="constant">SD_JOURNAL_SYSTEM</code>
  36                 will cause journal files of system services and the
  37                 kernel (in opposition to user session processes) to
  38                 be opened. <code class="constant">SD_JOURNAL_CURRENT_USER</code>
  39                 will cause journal files of the current user to be
  40                 opened. If neither <code class="constant">SD_JOURNAL_SYSTEM</code>
  41                 nor <code class="constant">SD_JOURNAL_CURRENT_USER</code> are
  42                 specified, all journal file types will be opened.</p><p><code class="function">sd_journal_open_directory()</code>
  43                 is similar to <code class="function">sd_journal_open()</code>
  44                 but takes an absolute directory path as argument. All
  45                 journal files in this directory will be opened and
  46                 interleaved automatically. This call also takes a
  47                 flags argument, but it must be passed as 0 as no flags
  48                 are currently understood for this call.</p><p><code class="function">sd_journal_open_files()</code>
  49                 is similar to <code class="function">sd_journal_open()</code>
  50                 but takes a <code class="constant">NULL</code>-terminated list
  51                 of file paths to open. All files will be opened and
  52                 interleaved automatically. This call also takes a
  53                 flags argument, but it must be passed as 0 as no flags
  54                 are currently understood for this call. Please note
  55                 that in the case of a live journal, this function is only
  56                 useful for debugging, because individual journal files
  57                 can be rotated at any moment, and the opening of
  58                 specific files is inherently racy.</p><p><code class="function">sd_journal_open_container()</code>
  59                 is similar to <code class="function">sd_journal_open()</code>
  60                 but opens the journal files of a running
  61                 OS container. The specified machine name refers to a
  62                 container that is registered with
  63                 <a href="systemd-machined.html"><span class="citerefentry"><span class="refentrytitle">systemd-machined</span>(8)</span></a>.</p><p><code class="varname">sd_journal</code> objects cannot be
  64                 used in the child after a fork. Functions which take a
  65                 journal object as an argument
  66                 (<code class="function">sd_journal_next()</code> and others)
  67                 will return <code class="constant">-ECHILD</code> after a fork.
  68                 </p><p><code class="function">sd_journal_close()</code> will
  69                 close the journal context allocated with
  70                 <code class="function">sd_journal_open()</code> or
  71                 <code class="function">sd_journal_open_directory()</code> and
  72                 free its resources.</p><p>When opening the journal only journal files
  73                 accessible to the calling user will be opened. If
  74                 journal files are not accessible to the caller, this
  75                 will be silently ignored.</p><p>See
  76                 <a href="sd_journal_next.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_next</span>(3)</span></a>
  77                 for an example of how to iterate through the journal
  78                 after opening it with
  79                 <code class="function">sd_journal_open()</code>.</p><p>A journal context object returned by
  80                 <code class="function">sd_journal_open()</code> references a
  81                 specific journal entry as <span class="emphasis"><em>current</em></span> entry,
  82                 similar to a file seek index in a classic file system
  83                 file, but without absolute positions. It may be
  84                 altered with
  85                 <a href="sd_journal_next.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_next</span>(3)</span></a>
  86                 and
  87                 <a href="sd_journal_seek_head.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_seek_head</span>(3)</span></a>
  88                 and related calls. The current entry position may be
  89                 exported in <span class="emphasis"><em>cursor</em></span> strings, as accessible
  90                 via
  91                 <a href="sd_journal_get_cursor.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_get_cursor</span>(3)</span></a>. Cursor
  92                 strings may be used to globally identify a specific
  93                 journal entry in a stable way and then later to seek
  94                 to it (or if the specific entry is not available
  95                 locally, to its closest entry in time)
  96                 <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
  97                 <code class="function">sd_journal_get_fd()</code> and related
  98                 calls.</p></div><div class="refsect1"><a name="idm139693586294336"></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>,
  99                 <code class="function">sd_journal_open_directory()</code>, and
 100                 <code class="function">sd_journal_open_files()</code> calls
 101                 return 0 on success or a negative errno-style error
 102                 code. <code class="function">sd_journal_close()</code> returns
 103                 nothing.</p></div><div class="refsect1"><a name="idm139693586290128"></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>,
 104                 <code class="function">sd_journal_open_directory()</code> and
 105                 <code class="function">sd_journal_close()</code> interfaces are
 106                 available as a shared library, which can be compiled and
 107                 linked to with the
 108                 <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>
 109                 file.</p></div><div class="refsect1"><a name="idm139693586284960"></a><h2 id="History">History<a class="headerlink" title="Permalink to this headline" href="#History">¶</a></h2><p><code class="function">sd_journal_open()</code>,
 110                 <code class="function">sd_journal_close()</code>,
 111                 <code class="constant">SD_JOURNAL_LOCAL_ONLY</code>,
 112                 <code class="constant">SD_JOURNAL_RUNTIME_ONLY</code>,
 113                 <code class="constant">SD_JOURNAL_SYSTEM_ONLY</code> were added
 114                 in systemd-38.</p><p><code class="function">sd_journal_open_directory()</code>
 115                 was added in systemd-187.</p><p><code class="constant">SD_JOURNAL_SYSTEM</code>,
 116                 <code class="constant">SD_JOURNAL_CURRENT_USER</code>,
 117                 and <code class="function">sd_journal_open_files()</code>
 118                 were added in systemd-205.
 119                 <code class="constant">SD_JOURNAL_SYSTEM_ONLY</code>
 120                 was deprecated.</p></div><div class="refsect1"><a name="idm139693581595616"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p>
 121                         <a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>,
 122                         <a href="sd-journal.html"><span class="citerefentry"><span class="refentrytitle">sd-journal</span>(3)</span></a>,
 123                         <a href="sd_journal_next.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_next</span>(3)</span></a>,
 124                         <a href="sd_journal_get_data.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_get_data</span>(3)</span></a>,
 125                         <a href="systemd-machined.html"><span class="citerefentry"><span class="refentrytitle">systemd-machined</span>(8)</span></a>
 126                 </p></div></div></body></html>