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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_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_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">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="idm274677924448"></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 |
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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 | |
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26 | a <code class="varname">sd_journal</code> pointer, which on |
| 27 | success will contain a journal context object. The | |
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28 | second argument is a flags field, which may consist of |
| 29 | the following flags ORed together: | |
| 14228c0d | 30 | <code class="constant">SD_JOURNAL_LOCAL_ONLY</code> makes sure |
| 663996b3 | 31 | only journal files generated on the local machine will |
| 14228c0d | 32 | be opened. <code class="constant">SD_JOURNAL_RUNTIME_ONLY</code> |
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33 | makes sure only volatile journal files will be opened, |
| 34 | excluding those which are stored on persistent | |
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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> | |
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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 | |
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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="varname">sd_journal</code> objects cannot be | |
| 59 | used in the child after a fork. Functions which take a | |
| 60 | journal object as an argument | |
| 61 | (<code class="function">sd_journal_next()</code> and others) | |
| 62 | will return <code class="constant">-ECHILD</code> after a fork. | |
| 63 | </p><p><code class="function">sd_journal_close()</code> will | |
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64 | close the journal context allocated with |
| 65 | <code class="function">sd_journal_open()</code> or | |
| 66 | <code class="function">sd_journal_open_directory()</code> and | |
| 67 | free its resources.</p><p>When opening the journal only journal files | |
| 68 | accessible to the calling user will be opened. If | |
| 14228c0d | 69 | journal files are not accessible to the caller, this |
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70 | will be silently ignored.</p><p>See |
| 71 | <a href="sd_journal_next.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_next</span>(3)</span></a> | |
| 14228c0d | 72 | for an example of how to iterate through the journal |
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73 | after opening it with |
| 74 | <code class="function">sd_journal_open()</code>.</p><p>A journal context object returned by | |
| 75 | <code class="function">sd_journal_open()</code> references a | |
| 76 | specific journal entry as <span class="emphasis"><em>current</em></span> entry, | |
| 77 | similar to a file seek index in a classic file system | |
| 78 | file, but without absolute positions. It may be | |
| 79 | altered with | |
| 80 | <a href="sd_journal_next.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_next</span>(3)</span></a> | |
| 81 | and | |
| 82 | <a href="sd_journal_seek_head.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_seek_head</span>(3)</span></a> | |
| 83 | and related calls. The current entry position may be | |
| 84 | exported in <span class="emphasis"><em>cursor</em></span> strings, as accessible | |
| 85 | via | |
| 86 | <a href="sd_journal_get_cursor.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_get_cursor</span>(3)</span></a>. Cursor | |
| 87 | strings may be used to globally identify a specific | |
| 88 | journal entry in a stable way and then later to seek | |
| 89 | to it (or if the specific entry is not available | |
| 90 | locally, to its closest entry in time) | |
| 91 | <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 | |
| 92 | <code class="function">sd_journal_get_fd()</code> and related | |
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93 | calls.</p></div><div class="refsect1"><a name="idm274677893168"></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>, |
| 94 | <code class="function">sd_journal_open_directory()</code>, and | |
| 95 | <code class="function">sd_journal_open_files()</code> calls | |
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96 | return 0 on success or a negative errno-style error |
| 97 | code. <code class="function">sd_journal_close()</code> returns | |
| 14228c0d | 98 | nothing.</p></div><div class="refsect1"><a name="idm274677888960"></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>, |
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99 | <code class="function">sd_journal_open_directory()</code> and |
| 100 | <code class="function">sd_journal_close()</code> interfaces are | |
| 14228c0d | 101 | available as a shared library, which can be compiled and |
| 663996b3 | 102 | linked to with the |
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103 | <code class="constant">libsystemd-journal</code> <a href="pkg-config.html"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a> |
| 104 | file.</p></div><div class="refsect1"><a name="idm274677884112"></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>, | |
| 105 | <code class="function">sd_journal_close()</code>, | |
| 106 | <code class="constant">SD_JOURNAL_LOCAL_ONLY</code>, | |
| 107 | <code class="constant">SD_JOURNAL_RUNTIME_ONLY</code>, | |
| 108 | <code class="constant">SD_JOURNAL_SYSTEM_ONLY</code> were added | |
| 109 | in systemd-38.</p><p><code class="function">sd_journal_open_directory()</code> | |
| 110 | was added in systemd-187.</p><p><code class="constant">SD_JOURNAL_SYSTEM</code>, | |
| 111 | <code class="constant">SD_JOURNAL_CURRENT_USER</code>, | |
| 112 | and <code class="function">sd_journal_open_files()</code> | |
| 113 | were added in systemd-205. | |
| 114 | <code class="constant">SD_JOURNAL_SYSTEM_ONLY</code> | |
| 115 | was deprecated.</p></div><div class="refsect1"><a name="idm274672909856"></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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116 | <a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>, |
| 117 | <a href="sd-journal.html"><span class="citerefentry"><span class="refentrytitle">sd-journal</span>(3)</span></a>, | |
| 118 | <a href="sd_journal_next.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_next</span>(3)</span></a>, | |
| 119 | <a href="sd_journal_get_data.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_get_data</span>(3)</span></a> | |
| 120 | </p></div></div></body></html> |