| <?xml version='1.0'?> <!--*-nxml-*--> |
| <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" |
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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_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> |