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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 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>...
+ <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);
+ 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>
- <refsect1>
- <title>See Also</title>
+ <refsect1>
+ <title>See Also</title>
- <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>
+ <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