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<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>sd_journal_open</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><style>
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<span style="float:right">systemd 221</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="idm47157569776992"></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
for reading. It will find all journal files automatically and
interleave them automatically when reading. As first argument it
takes a pointer to a <code class="varname">sd_journal</code> pointer, which
on success will contain a journal context object. The second
argument is a flags field, which may consist of the following
flags ORed together: <code class="constant">SD_JOURNAL_LOCAL_ONLY</code>
makes sure only journal files generated on the local machine will
be opened. <code class="constant">SD_JOURNAL_RUNTIME_ONLY</code> makes sure
only volatile journal files will be opened, excluding those which
are stored on persistent storage.
<code class="constant">SD_JOURNAL_SYSTEM</code> will cause journal files of
system services and the kernel (in opposition to user session
processes) to be opened.
<code class="constant">SD_JOURNAL_CURRENT_USER</code> will cause journal
files of the current user to be opened. If neither
<code class="constant">SD_JOURNAL_SYSTEM</code> nor
<code class="constant">SD_JOURNAL_CURRENT_USER</code> are specified, all
journal file types will be opened.</p><p><code class="function">sd_journal_open_directory()</code> is similar
to <code class="function">sd_journal_open()</code> but takes an absolute
directory path as argument. All journal files in this directory
will be opened and interleaved automatically. This call also takes
a flags argument, but it must be passed as 0 as no flags are
currently understood for this call.</p><p><code class="function">sd_journal_open_files()</code> is similar to
<code class="function">sd_journal_open()</code> but takes a
<code class="constant">NULL</code>-terminated list of file paths to open.
All files will be opened and interleaved automatically. This call
also takes a flags argument, but it must be passed as 0 as no
flags are currently understood for this call. Please note that in
the case of a live journal, this function is only useful for
debugging, because individual journal files can be rotated at any
moment, and the opening of specific files is inherently
racy.</p><p><code class="function">sd_journal_open_container()</code> is similar
to <code class="function">sd_journal_open()</code> but opens the journal
files of a running OS container. The specified machine name refers
to a container that is registered with
<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
child after a fork. Functions which take a journal object as an
argument (<code class="function">sd_journal_next()</code> and others) will
return <code class="constant">-ECHILD</code> after a fork.
</p><p><code class="function">sd_journal_close()</code> will close the
journal context allocated with
<code class="function">sd_journal_open()</code> or
<code class="function">sd_journal_open_directory()</code> and free its
resources.</p><p>When opening the journal only journal files accessible to
the calling user will be opened. If journal files are not
accessible to the caller, this will be silently ignored.</p><p>See
<a href="sd_journal_next.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_next</span>(3)</span></a>
for an example of how to iterate through the journal after opening
it with <code class="function">sd_journal_open()</code>.</p><p>A journal context object returned by
<code class="function">sd_journal_open()</code> references a specific
journal entry as <span class="emphasis"><em>current</em></span> entry, similar to a
file seek index in a classic file system file, but without
absolute positions. It may be altered with
<a href="sd_journal_next.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_next</span>(3)</span></a>
and
<a href="sd_journal_seek_head.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_seek_head</span>(3)</span></a>
and related calls. The current entry position may be exported in
<span class="emphasis"><em>cursor</em></span> strings, as accessible via
<a href="sd_journal_get_cursor.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_get_cursor</span>(3)</span></a>.
Cursor strings may be used to globally identify a specific journal
entry in a stable way and then later to seek to it (or if the
specific entry is not available locally, to its closest entry in
time)
<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
<code class="function">sd_journal_get_fd()</code> and related calls.</p></div><div class="refsect1"><a name="idm47157569752720"></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>,
<code class="function">sd_journal_open_directory()</code>, and
<code class="function">sd_journal_open_files()</code> calls return 0 on
success or a negative errno-style error code.
<code class="function">sd_journal_close()</code> returns nothing.</p></div><div class="refsect1"><a name="idm47157569748976"></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>,
<code class="function">sd_journal_open_directory()</code> and
<code class="function">sd_journal_close()</code> interfaces are available
as a shared library, which can be compiled and linked to with the
<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>
file.</p></div><div class="refsect1"><a name="idm47157569744448"></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>,
<code class="function">sd_journal_close()</code>,
<code class="constant">SD_JOURNAL_LOCAL_ONLY</code>,
<code class="constant">SD_JOURNAL_RUNTIME_ONLY</code>,
<code class="constant">SD_JOURNAL_SYSTEM_ONLY</code> were added in
systemd-38.</p><p><code class="function">sd_journal_open_directory()</code> was added
in systemd-187.</p><p><code class="constant">SD_JOURNAL_SYSTEM</code>,
<code class="constant">SD_JOURNAL_CURRENT_USER</code>, and
<code class="function">sd_journal_open_files()</code> were added in
systemd-205. <code class="constant">SD_JOURNAL_SYSTEM_ONLY</code> was
deprecated.</p></div><div class="refsect1"><a name="idm47157569738112"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p>
<a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>,
<a href="sd-journal.html"><span class="citerefentry"><span class="refentrytitle">sd-journal</span>(3)</span></a>,
<a href="sd_journal_next.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_next</span>(3)</span></a>,
<a href="sd_journal_get_data.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_get_data</span>(3)</span></a>,
<a href="systemd-machined.html"><span class="citerefentry"><span class="refentrytitle">systemd-machined</span>(8)</span></a>
</p></div></div></body></html>
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