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Diffstat (limited to 'src/libsystemd/sd_journal_add_match.xml')
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diff --git a/src/libsystemd/sd_journal_add_match.xml b/src/libsystemd/sd_journal_add_match.xml new file mode 100644 index 0000000000..7c64329aed --- /dev/null +++ b/src/libsystemd/sd_journal_add_match.xml @@ -0,0 +1,219 @@ +<?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_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>. + Parameter <parameter>data</parameter> must be of the form + <literal><replaceable>FIELD</replaceable>=<replaceable>value</replaceable></literal>, + where the <replaceable>FIELD</replaceable> 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 <replaceable>value</replaceable> part may be anything, including binary. Parameter + <parameter>size</parameter> specifies the number of bytes in <parameter>data</parameter> + (i.e. the length of <replaceable>FIELD</replaceable>, plus one, plus the length of + <replaceable>value</replaceable>). Parameter <parameter>size</parameter> may also be + specified as <constant>0</constant>, in which case <parameter>data</parameter> + must be a <constant>NUL</constant>-terminated string, and the bytes before the terminating + zero are used as the match.</para> + + <para>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>All functions listed here are thread-agnostic and only a single thread may operate + on a given <structname>sd_journal</structname> object.</para> + + <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> |