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-<?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">
-
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--->
-
-<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_add_conjunction</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_add_conjunction</function></funcdef>
- <paramdef>sd_journal *<parameter>j</parameter></paramdef>
- </funcprototype>
-
- <funcprototype>
- <funcdef>void <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 since the
- last invocation of
- <function>sd_journal_add_disjunction()</function> or
- <function>sd_journal_add_conjunction()</function> are combined in
- an OR with all matches added afterwards, until
- <function>sd_journal_add_disjunction()</function> or
- <function>sd_journal_add_conjunction()</function> is invoked again
- to begin the next OR or AND term. </para>
-
- <para><function>sd_journal_add_conjunction()</function> may be
- used to insert a conjunction (i.e. logical AND) in the match list.
- If this call is invoked, all previously added matches since the
- last invocation of
- <function>sd_journal_add_conjunction()</function> are combined in
- an AND with all matches added afterwards, until
- <function>sd_journal_add_conjunction()</function> is invoked again
- to begin the next AND term. The combination of
- <function>sd_journal_add_match()</function>,
- <function>sd_journal_add_disjunction()</function> and
- <function>sd_journal_add_conjunction()</function> may be used to
- build complex search terms, even though full logical expressions
- are not available. Note that
- <function>sd_journal_add_conjunction()</function> operates one
- level 'higher' than
- <function>sd_journal_add_disjunction()</function>. It is hence
- possible to build an expression of AND terms, consisting of OR
- terms, consisting of AND terms, consisting of OR terms of matches
- (the latter OR expression is implicitly created for matches with
- the same field name, see above).</para>
-
- <para><function>sd_journal_flush_matches()</function> may be used
- to flush all matches, disjunction and conjunction 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 the 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>,
- <function>sd_journal_add_disjunction()</function> and
- <function>sd_journal_add_conjunction()</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>,
- <function>sd_journal_add_conjunction()</function> and
- <function>sd_journal_flush_matches()</function>
- interfaces are available as a shared library, which can
- be compiled and linked to with the
- <constant>libsystemd</constant> <citerefentry project='die-net'><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", 0);
- sd_journal_add_match(j, "PRIORITY=0", 0);
- sd_journal_add_match(j, "PRIORITY=1", 0);
- sd_journal_add_match(j, "PRIORITY=2", 0);
- sd_journal_add_match(j, "PRIORITY=3", 0);
- sd_journal_add_disjunction(j);
- sd_journal_add_match(j, "MESSAGE_ID=03bb1dab98ab4ecfbf6fff2738bdd964", 0);
-}</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 / blobdiff