--- /dev/null
+<?xml version='1.0'?> <!--*-nxml-*-->
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
+ "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+
+<!--
+ This file is part of systemd.
+
+ Copyright 2012 Lennart Poettering
+
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ systemd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+-->
+
+<refentry id="sd_journal_add_match">
+
+ <refentryinfo>
+ <title>sd_journal_add_match</title>
+ <productname>systemd</productname>
+
+ <authorgroup>
+ <author>
+ <contrib>Developer</contrib>
+ <firstname>Lennart</firstname>
+ <surname>Poettering</surname>
+ <email>lennart@poettering.net</email>
+ </author>
+ </authorgroup>
+ </refentryinfo>
+
+ <refmeta>
+ <refentrytitle>sd_journal_add_match</refentrytitle>
+ <manvolnum>3</manvolnum>
+ </refmeta>
+
+ <refnamediv>
+ <refname>sd_journal_add_match</refname>
+ <refname>sd_journal_add_disjunction</refname>
+ <refname>sd_journal_flush_matches</refname>
+ <refpurpose>Add or remove entry matches</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <funcsynopsis>
+ <funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo>
+
+ <funcprototype>
+ <funcdef>int <function>sd_journal_add_match</function></funcdef>
+ <paramdef>sd_journal* <parameter>j</parameter></paramdef>
+ <paramdef>const void* <parameter>data</parameter></paramdef>
+ <paramdef>size_t <parameter>size</parameter></paramdef>
+ </funcprototype>
+
+ <funcprototype>
+ <funcdef>int <function>sd_journal_add_disjunction</function></funcdef>
+ <paramdef>sd_journal* <parameter>j</parameter></paramdef>
+ </funcprototype>
+
+ <funcprototype>
+ <funcdef>int <function>sd_journal_flush_matches</function></funcdef>
+ <paramdef>sd_journal* <parameter>j</parameter></paramdef>
+ </funcprototype>
+ </funcsynopsis>
+ </refsynopsisdiv>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para><function>sd_journal_add_match()</function> adds
+ a match by which to filter the entries of the journal
+ file. Matches applied with this call will filter what
+ can be iterated through and read from the journal file
+ via calls like
+ <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ and
+ <citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>. Matches
+ are of the form <literal>FIELD=value</literal>, where
+ the field part is a short uppercase string consisting
+ only of 0-9, A-Z and the underscore. It may not begin
+ with two underscores or be the empty string. The value
+ part may be any value, including binary. If a match is
+ applied only entries with this field set will be
+ iterated. Multiple matches may be active at the same
+ time: if they apply to different fields only entries
+ with both fields set like this will be iterated, if
+ they apply to the same fields only entries where the
+ field takes one of the specified values will be
+ iterated. Well known fields are documented in
+ <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>. Whenever
+ a new match is added the current entry position is
+ reset, and
+ <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry> (or a similar call)
+ needs to be called before entries can be read
+ again.</para>
+
+ <para><function>sd_journal_add_disjunction()</function>
+ may be used to insert a disjunction (i.e. logical OR)
+ in the match list. If this call is invoked all
+ previously added matches are combined in an OR with
+ all matches added afterwards, until
+ <function>sd_journal_add_disjunction()</function> is
+ invoked again to begin the next OR term. The
+ combination of
+ <function>sd_journal_add_match()</function> and
+ <function>sd_journal_add_disjunction()</function> may
+ be used to build complex search terms, even though
+ full logical expressions are not available.</para>
+
+ <para><function>sd_journal_flush_matches()</function>
+ may be used to flush all matches and disjunction terms
+ again. After this call all filtering is removed and
+ all entries in the journal will be iterated
+ again.</para>
+
+ <para>Note that filtering via matches only applies to
+ way the journal is read, it has no effect on storage
+ on disk.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Return Value</title>
+
+ <para><function>sd_journal_add_match()</function> and
+ <function>sd_journal_add_disjunction()</function>
+ return 0 on success or a negative errno-style error
+ code. <function>sd_journal_flush_matches()</function>
+ returns nothing.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Notes</title>
+
+ <para>The <function>sd_journal_add_match()</function>,
+ <function>sd_journal_add_disjunction()</function> and
+ <function>sd_journal_flush_matches()</function> interfaces are
+ available as shared library, which can be compiled and
+ linked to with the
+ <literal>libsystemd-journal</literal>
+ <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+ file.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Examples</title>
+
+ <para>The following example adds matches to a journal
+ context object to iterate only through messages
+ generated by the Avahi service at the four error log
+ levels, plus all messages of the message ID
+ 03bb1dab98ab4ecfbf6fff2738bdd964 coming from any
+ service (this example lacks the necessary error
+ checking):</para>
+
+ <programlisting>...
+int add_matches(sd_journal *j) {
+ sd_journal_add_match(j, "_SYSTEMD_UNIT=avahi-daemon.service");
+ sd_journal_add_match(j, "PRIORITY=0");
+ sd_journal_add_match(j, "PRIORITY=1");
+ sd_journal_add_match(j, "PRIORITY=2");
+ sd_journal_add_match(j, "PRIORITY=3");
+ sd_journal_add_disjunction(j);
+ sd_journal_add_match(j, "MESSAGE_ID=03bb1dab98ab4ecfbf6fff2738bdd964");
+}</programlisting>
+
+ </refsect1>
+
+ <refsect1>
+ <title>See Also</title>
+
+ <para>
+ <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_journal_open</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ </para>
+ </refsect1>
+
+</refentry>
~ianmdlvl / elogind.git / commitdiff