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22 | <a href="../libudev/index.html">gudev </a><span style="float:right">systemd 219</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 <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_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="idm140423144980192"></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 the log journal |
| 23 | for reading. It will find all journal files automatically and | |
| 24 | interleave them automatically when reading. As first argument it | |
| 25 | takes a pointer to a <code class="varname">sd_journal</code> pointer, which | |
| 26 | on success will contain a journal context object. The second | |
| 27 | argument is a flags field, which may consist of the following | |
| 28 | flags ORed together: <code class="constant">SD_JOURNAL_LOCAL_ONLY</code> | |
| 29 | makes sure only journal files generated on the local machine will | |
| 30 | be opened. <code class="constant">SD_JOURNAL_RUNTIME_ONLY</code> makes sure | |
| 31 | only volatile journal files will be opened, excluding those which | |
| 32 | are stored on persistent storage. | |
| 33 | <code class="constant">SD_JOURNAL_SYSTEM</code> will cause journal files of | |
| 34 | system services and the kernel (in opposition to user session | |
| 35 | processes) to be opened. | |
| 36 | <code class="constant">SD_JOURNAL_CURRENT_USER</code> will cause journal | |
| 37 | files of the current user to be opened. If neither | |
| 38 | <code class="constant">SD_JOURNAL_SYSTEM</code> nor | |
| 39 | <code class="constant">SD_JOURNAL_CURRENT_USER</code> are specified, all | |
| 40 | journal file types will be opened.</p><p><code class="function">sd_journal_open_directory()</code> is similar | |
| 41 | to <code class="function">sd_journal_open()</code> but takes an absolute | |
| 42 | directory path as argument. All journal files in this directory | |
| 43 | will be opened and interleaved automatically. This call also takes | |
| 44 | a flags argument, but it must be passed as 0 as no flags are | |
| 45 | currently understood for this call.</p><p><code class="function">sd_journal_open_files()</code> is similar to | |
| 46 | <code class="function">sd_journal_open()</code> but takes a | |
| 47 | <code class="constant">NULL</code>-terminated list of file paths to open. | |
| 48 | All files will be opened and interleaved automatically. This call | |
| 49 | also takes a flags argument, but it must be passed as 0 as no | |
| 50 | flags are currently understood for this call. Please note that in | |
| 51 | the case of a live journal, this function is only useful for | |
| 52 | debugging, because individual journal files can be rotated at any | |
| 53 | moment, and the opening of specific files is inherently | |
| 54 | racy.</p><p><code class="function">sd_journal_open_container()</code> is similar | |
| 55 | to <code class="function">sd_journal_open()</code> but opens the journal | |
| 56 | files of a running OS container. The specified machine name refers | |
| 57 | to a container that is registered with | |
| 58 | <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 used in the | |
| 59 | child after a fork. Functions which take a journal object as an | |
| 60 | argument (<code class="function">sd_journal_next()</code> and others) will | |
| 61 | return <code class="constant">-ECHILD</code> after a fork. | |
| 62 | </p><p><code class="function">sd_journal_close()</code> will close the | |
| 63 | journal context allocated with | |
| 64 | <code class="function">sd_journal_open()</code> or | |
| 65 | <code class="function">sd_journal_open_directory()</code> and free its | |
| 66 | resources.</p><p>When opening the journal only journal files accessible to | |
| 67 | the calling user will be opened. If journal files are not | |
| 68 | accessible to the caller, this will be silently ignored.</p><p>See | |
| 69 | <a href="sd_journal_next.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_next</span>(3)</span></a> | |
| 70 | for an example of how to iterate through the journal after opening | |
| 71 | it with <code class="function">sd_journal_open()</code>.</p><p>A journal context object returned by | |
| 72 | <code class="function">sd_journal_open()</code> references a specific | |
| 73 | journal entry as <span class="emphasis"><em>current</em></span> entry, similar to a | |
| 74 | file seek index in a classic file system file, but without | |
| 75 | absolute positions. It may be altered with | |
| 76 | <a href="sd_journal_next.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_next</span>(3)</span></a> | |
| 77 | and | |
| 78 | <a href="sd_journal_seek_head.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_seek_head</span>(3)</span></a> | |
| 79 | and related calls. The current entry position may be exported in | |
| 80 | <span class="emphasis"><em>cursor</em></span> strings, as accessible via | |
| 81 | <a href="sd_journal_get_cursor.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_get_cursor</span>(3)</span></a>. | |
| 82 | Cursor strings may be used to globally identify a specific journal | |
| 83 | entry in a stable way and then later to seek to it (or if the | |
| 84 | specific entry is not available locally, to its closest entry in | |
| 85 | time) | |
| 86 | <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 | |
| 87 | <code class="function">sd_journal_get_fd()</code> and related calls.</p></div><div class="refsect1"><a name="idm140423144946896"></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>, | |
| 88 | <code class="function">sd_journal_open_directory()</code>, and | |
| 89 | <code class="function">sd_journal_open_files()</code> calls return 0 on | |
| 90 | success or a negative errno-style error code. | |
| 91 | <code class="function">sd_journal_close()</code> returns nothing.</p></div><div class="refsect1"><a name="idm140423144942720"></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>, | |
| 92 | <code class="function">sd_journal_open_directory()</code> and | |
| 93 | <code class="function">sd_journal_close()</code> interfaces are available | |
| 94 | as a shared library, which can be compiled and linked to with the | |
| 95 | <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> | |
| 96 | file.</p></div><div class="refsect1"><a name="idm140423139973184"></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>, | |
| 97 | <code class="function">sd_journal_close()</code>, | |
| 98 | <code class="constant">SD_JOURNAL_LOCAL_ONLY</code>, | |
| 99 | <code class="constant">SD_JOURNAL_RUNTIME_ONLY</code>, | |
| 100 | <code class="constant">SD_JOURNAL_SYSTEM_ONLY</code> were added in | |
| 101 | systemd-38.</p><p><code class="function">sd_journal_open_directory()</code> was added | |
| 102 | in systemd-187.</p><p><code class="constant">SD_JOURNAL_SYSTEM</code>, | |
| 103 | <code class="constant">SD_JOURNAL_CURRENT_USER</code>, and | |
| 104 | <code class="function">sd_journal_open_files()</code> were added in | |
| 105 | systemd-205. <code class="constant">SD_JOURNAL_SYSTEM_ONLY</code> was | |
| 106 | deprecated.</p></div><div class="refsect1"><a name="idm140423139966848"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p> | |
| 107 | <a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>, | |
| 108 | <a href="sd-journal.html"><span class="citerefentry"><span class="refentrytitle">sd-journal</span>(3)</span></a>, | |
| 109 | <a href="sd_journal_next.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_next</span>(3)</span></a>, | |
| 110 | <a href="sd_journal_get_data.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_get_data</span>(3)</span></a>, | |
| 111 | <a href="systemd-machined.html"><span class="citerefentry"><span class="refentrytitle">systemd-machined</span>(8)</span></a> | |
| 112 | </p></div></div></body></html> |