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12b42c7667
This did not really work out as we had hoped. Trying to do this upstream introduced several problems that probably makes it better suited as a downstream patch after all. At any rate, it is not releaseable in the current state, so we at least need to revert this before the release. * by adjusting the path to binaries, but not do the same thing to the search path we end up with inconsistent man-pages. Adjusting the search path too would be quite messy, and it is not at all obvious that this is worth the effort, but at any rate it would have to be done before we could ship this. * this means that distributed man-pages does not make sense as they depend on config options, and for better or worse we are still distributing man pages, so that is something that definitely needs sorting out before we could ship with this patch. * we have long held that split-usr is only minimally supported in order to boot, and something we hope will eventually go away. So before we start adding even more magic/effort in order to make this work nicely, we should probably question if it makes sense at all.
209 lines
8.7 KiB
XML
209 lines
8.7 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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This file is part of systemd.
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Copyright 2012 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="sd_journal_add_match">
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<refentryinfo>
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<title>sd_journal_add_match</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>sd_journal_add_match</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>sd_journal_add_match</refname>
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<refname>sd_journal_add_disjunction</refname>
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<refname>sd_journal_add_conjunction</refname>
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<refname>sd_journal_flush_matches</refname>
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<refpurpose>Add or remove entry matches</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo>
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<funcprototype>
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<funcdef>int <function>sd_journal_add_match</function></funcdef>
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<paramdef>sd_journal *<parameter>j</parameter></paramdef>
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<paramdef>const void *<parameter>data</parameter></paramdef>
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<paramdef>size_t <parameter>size</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_journal_add_disjunction</function></funcdef>
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<paramdef>sd_journal *<parameter>j</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_journal_add_conjunction</function></funcdef>
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<paramdef>sd_journal *<parameter>j</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>void <function>sd_journal_flush_matches</function></funcdef>
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<paramdef>sd_journal *<parameter>j</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><function>sd_journal_add_match()</function> adds a match by
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which to filter the entries of the journal file. Matches applied
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with this call will filter what can be iterated through and read
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from the journal file via calls like
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<citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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and
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<citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
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Matches are of the form <literal>FIELD=value</literal>, where the
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field part is a short uppercase string consisting only of 0-9, A-Z
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and the underscore. It may not begin with two underscores or be
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the empty string. The value part may be any value, including
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binary. If a match is applied, only entries with this field set
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will be iterated. Multiple matches may be active at the same time:
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If they apply to different fields, only entries with both fields
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set like this will be iterated. If they apply to the same fields,
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only entries where the field takes one of the specified values
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will be iterated. Well known fields are documented in
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<citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
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Whenever a new match is added the current entry position is reset,
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and
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<citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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(or a similar call) needs to be called before entries can be read
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again.</para>
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<para><function>sd_journal_add_disjunction()</function> may be
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used to insert a disjunction (i.e. logical OR) in the match list.
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If this call is invoked, all previously added matches since the
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last invocation of
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<function>sd_journal_add_disjunction()</function> or
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<function>sd_journal_add_conjunction()</function> are combined in
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an OR with all matches added afterwards, until
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<function>sd_journal_add_disjunction()</function> or
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<function>sd_journal_add_conjunction()</function> is invoked again
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to begin the next OR or AND term. </para>
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<para><function>sd_journal_add_conjunction()</function> may be
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used to insert a conjunction (i.e. logical AND) in the match list.
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If this call is invoked, all previously added matches since the
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last invocation of
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<function>sd_journal_add_conjunction()</function> are combined in
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an AND with all matches added afterwards, until
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<function>sd_journal_add_conjunction()</function> is invoked again
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to begin the next AND term. The combination of
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<function>sd_journal_add_match()</function>,
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<function>sd_journal_add_disjunction()</function> and
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<function>sd_journal_add_conjunction()</function> may be used to
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build complex search terms, even though full logical expressions
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are not available. Note that
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<function>sd_journal_add_conjunction()</function> operates one
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level 'higher' than
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<function>sd_journal_add_disjunction()</function>. It is hence
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possible to build an expression of AND terms, consisting of OR
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terms, consisting of AND terms, consisting of OR terms of matches
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(the latter OR expression is implicitly created for matches with
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the same field name, see above).</para>
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<para><function>sd_journal_flush_matches()</function> may be used
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to flush all matches, disjunction and conjunction terms again.
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After this call all filtering is removed and all entries in the
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journal will be iterated again.</para>
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<para>Note that filtering via matches only applies to the way the
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journal is read, it has no effect on storage on disk.</para>
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</refsect1>
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<refsect1>
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<title>Return Value</title>
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<para><function>sd_journal_add_match()</function>,
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<function>sd_journal_add_disjunction()</function> and
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<function>sd_journal_add_conjunction()</function>
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return 0 on success or a negative errno-style error
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code. <function>sd_journal_flush_matches()</function>
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returns nothing.</para>
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</refsect1>
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<refsect1>
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<title>Notes</title>
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<para>The <function>sd_journal_add_match()</function>,
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<function>sd_journal_add_disjunction()</function>,
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<function>sd_journal_add_conjunction()</function> and
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<function>sd_journal_flush_matches()</function>
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interfaces are available as a shared library, which can
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be compiled and linked to with the
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<constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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file.</para>
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</refsect1>
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<refsect1>
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<title>Examples</title>
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<para>The following example adds matches to a journal context
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object to iterate only through messages generated by the Avahi
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service at the four error log levels, plus all messages of the
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message ID 03bb1dab98ab4ecfbf6fff2738bdd964 coming from any
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service (this example lacks the necessary error checking):</para>
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<programlisting>...
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int add_matches(sd_journal *j) {
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sd_journal_add_match(j, "_SYSTEMD_UNIT=avahi-daemon.service", 0);
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sd_journal_add_match(j, "PRIORITY=0", 0);
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sd_journal_add_match(j, "PRIORITY=1", 0);
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sd_journal_add_match(j, "PRIORITY=2", 0);
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sd_journal_add_match(j, "PRIORITY=3", 0);
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sd_journal_add_disjunction(j);
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sd_journal_add_match(j, "MESSAGE_ID=03bb1dab98ab4ecfbf6fff2738bdd964", 0);
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}</programlisting>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_journal_open</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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