[thirdparty/systemd.git] / man / sd_journal_print.xml

<?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_print">

        <refentryinfo>
                <title>sd_journal_print</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_print</refentrytitle>
                <manvolnum>3</manvolnum>
        </refmeta>

        <refnamediv>
                <refname>sd_journal_print</refname>
                <refname>sd_journal_printv</refname>
                <refname>sd_journal_send</refname>
                <refname>sd_journal_sendv</refname>
                <refpurpose>Submit log entries to the journal</refpurpose>
        </refnamediv>

        <refsynopsisdiv>
                <funcsynopsis>
                        <funcsynopsisinfo>#include &lt;systemd/sd-journal.h&gt;</funcsynopsisinfo>

                        <funcprototype>
                                <funcdef>int <function>sd_journal_print</function></funcdef>
                                <paramdef>int <parameter>priority</parameter></paramdef>
                                <paramdef>const char* <parameter>format</parameter></paramdef>
                                <paramdef>...</paramdef>
                        </funcprototype>

                        <funcprototype>
                                <funcdef>int <function>sd_journal_printv</function></funcdef>
                                <paramdef>int <parameter>priority</parameter></paramdef>
                                <paramdef>const char* <parameter>format</parameter></paramdef>
                                <paramdef>va_list <parameter>ap</parameter></paramdef>
                        </funcprototype>

                        <funcprototype>
                                <funcdef>int <function>sd_journal_send</function></funcdef>
                                <paramdef>const char* <parameter>format</parameter></paramdef>
                                <paramdef>...</paramdef>
                        </funcprototype>

                        <funcprototype>
                                <funcdef>int <function>sd_journal_sendv</function></funcdef>
                                <paramdef>const struct iovec *<parameter>iov</parameter></paramdef>
                                <paramdef>int <parameter>n</parameter></paramdef>
                        </funcprototype>

                </funcsynopsis>
        </refsynopsisdiv>

        <refsect1>
                <title>Description</title>

                <para><function>sd_journal_print()</function> may be
                used to submit simple, plain text log entries to the
                system journal. The first argument is a priority
                value. This is followed by a format string and its
                parameters, similar to
                <citerefentry><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                or
                <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>. The
                priority value is one of
                <literal>LOG_EMERG</literal>,
                <literal>LOG_ALERT</literal>,
                <literal>LOG_CRIT</literal>,
                <literal>LOG_ERR</literal>,
                <literal>LOG_WARNING</literal>,
                <literal>LOG_NOTICE</literal>,
                <literal>LOG_INFO</literal>,
                <literal>LOG_DEBUG</literal>, as defined in
                <filename>syslog.h</filename>, see
                <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                for details. It is recommended to use this call to
                submit log messages in the application locale or system
                locale and in UTF-8 format, but no such restrictions
                are enforced.</para>

                <para><function>sd_journal_printv()</function> is
                similar to <function>sd_journal_print()</function> but
                takes a variable argument list encapsulated in an
                object of type <literal>va_list</literal> (see
                <citerefentry><refentrytitle>stdarg</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                for more information) instead of the format string. It
                is otherwise equivalent in behaviour.</para>

                <para><function>sd_journal_send()</function> may be
                used to submit structured log entries to the system
                journal. It takes a series of format strings, each
                immediately followed by their associated parameters,
                terminated by NULL. The strings passed should be of
                the format <literal>VARIABLE=value</literal>. The
                variable name must be in uppercase and consist only
                of characters, numbers and underscores, and may not
                begin with an underscore. The value can be of any size
                and format. It is highly recommended to submit
                text strings formatted in the UTF-8 character encoding
                only, and submit binary fields only when formatting in
                UTf-8 strings is not sensible. A number of well known
                fields are defined, see
                <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
                for details, but additional application defined fields
                may be used.</para>

                <para><function>sd_journal_sendv()</function> is
                similar to <function>sd_journal_send()</function> but
                takes an array of <literal>struct iovec</literal> (as
                defined in <filename>uio.h</filename>, see
                <citerefentry><refentrytitle>readv</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                for details) instead of the format string. Each
                structure should reference one field of the entry to
                submit. The second argument specifies the number of
                structures in the
                array. <function>sd_journal_sendv()</function> is
                particularly useful to submit binary objects to the
                journal where that is necessary.</para>

                <para>Note that <function>sd_journal_send()</function>
                is a wrapper around
                <function>sd_journal_sendv()</function> to make it
                easier to use when only text strings shall be
                submitted. Also, the following two calls are
                mostly equivalent:</para>

                <programlisting>sd_journal_print(LOG_INFO, "Hello World, this is PID %lu!", (unsigned long) getpid());

sd_journal_send("MESSAGE=Hello World, this is PID %lu!", (unsigned long) getpid(),
                "PRIORITY=%i", LOG_INFO,
                NULL);</programlisting>

                <para>Note that these calls implicitly add fields for
                the source file, function name and code line where
                invoked. This is implemented with macros. If this is
                not desired it can be turned off by defining
                SD_JOURNAL_SUPPRESS_LOCATION before including
                <filename>sd-journal.h</filename>.</para>

                <para><citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                and and <function>sd_journal_print()</function> may
                largely be used interchangably
                functionality-wise. However, note that log messages
                logged via the former take a different path to the
                journal server than the later, and hence global
                chronological ordering between the two streams cannot
                be guaranteed. Using
                <function>sd_journal_print()</function> has the
                benefit of logging source code line, file names, and
                functions as meta data along all entries, and
                guaranteeing chronological ordering with structured
                log entries that are generated via
                <function>sd_journal_send()</function>. Using
                <function>syslog()</function> has the benefit of being
                more portable.</para>
        </refsect1>

        <refsect1>
                <title>Return Value</title>

                <para>The four calls return 0 on success or a
                negative errno-style error code.</para>
        </refsect1>

        <refsect1>
                <title>Notes</title>

                <para>The <function>sd_journal_print()</function>,
                <function>sd_journal_printv()</function>,
                <function>sd_journal_send()</function> and
                <function>sd_journal_sendv()</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>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_stream_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
                </para>
        </refsect1>

</refentry>
Commit	Line	Data
a8eedf49 LP	1	<?xml version='1.0'?> <!---nxml--->
	2	<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
	3	"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
	4
	5	<!--
	6	This file is part of systemd.
	7
	8	Copyright 2012 Lennart Poettering
	9
	10	systemd is free software; you can redistribute it and/or modify it
	11	under the terms of the GNU Lesser General Public License as published by
	12	the Free Software Foundation; either version 2.1 of the License, or
	13	(at your option) any later version.
	14
	15	systemd is distributed in the hope that it will be useful, but
	16	WITHOUT ANY WARRANTY; without even the implied warranty of
	17	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	18	Lesser General Public License for more details.
	19
	20	You should have received a copy of the GNU Lesser General Public License
	21	along with systemd; If not, see <http://www.gnu.org/licenses/>.
	22	-->
	23
	24	<refentry id="sd_journal_print">
	25
	26	<refentryinfo>
	27	<title>sd_journal_print</title>
	28	<productname>systemd</productname>
	29
	30	<authorgroup>
	31	<author>
	32	<contrib>Developer</contrib>
	33	<firstname>Lennart</firstname>
	34	<surname>Poettering</surname>
	35	<email>lennart@poettering.net</email>
	36	</author>
	37	</authorgroup>
	38	</refentryinfo>
	39
	40	<refmeta>
	41	<refentrytitle>sd_journal_print</refentrytitle>
	42	<manvolnum>3</manvolnum>
	43	</refmeta>
	44
	45	<refnamediv>
	46	<refname>sd_journal_print</refname>
	47	<refname>sd_journal_printv</refname>
	48	<refname>sd_journal_send</refname>
	49	<refname>sd_journal_sendv</refname>
	50	<refpurpose>Submit log entries to the journal</refpurpose>
	51	</refnamediv>
	52
	53	<refsynopsisdiv>
	54	<funcsynopsis>
	55	<funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo>
	56
	57	<funcprototype>
	58	<funcdef>int <function>sd_journal_print</function></funcdef>
	59	<paramdef>int <parameter>priority</parameter></paramdef>
	60	<paramdef>const char* <parameter>format</parameter></paramdef>
	61	<paramdef>...</paramdef>
	62	</funcprototype>
	63
	64	<funcprototype>
65	<funcdef>int <function>sd_journal_printv</function></funcdef>
66	<paramdef>int <parameter>priority</parameter></paramdef>
67	<paramdef>const char* <parameter>format</parameter></paramdef>
68	<paramdef>va_list <parameter>ap</parameter></paramdef>
69	</funcprototype>
70
71	<funcprototype>
72	<funcdef>int <function>sd_journal_send</function></funcdef>
73	<paramdef>const char* <parameter>format</parameter></paramdef>
74	<paramdef>...</paramdef>
75	</funcprototype>
76
77	<funcprototype>
78	<funcdef>int <function>sd_journal_sendv</function></funcdef>
79	<paramdef>const struct iovec *<parameter>iov</parameter></paramdef>
80	<paramdef>int <parameter>n</parameter></paramdef>
81	</funcprototype>
82
83	</funcsynopsis>
84	</refsynopsisdiv>
85
86	<refsect1>
87	<title>Description</title>
88
89	<para><function>sd_journal_print()</function> may be
90	used to submit simple, plain text log entries to the
91	system journal. The first argument is a priority
92	value. This is followed by a format string and its
93	parameters, similar to
94	<citerefentry><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry>
95	or
96	<citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>. The
97	priority value is one of
98	<literal>LOG_EMERG</literal>,
99	<literal>LOG_ALERT</literal>,
100	<literal>LOG_CRIT</literal>,
101	<literal>LOG_ERR</literal>,
102	<literal>LOG_WARNING</literal>,
103	<literal>LOG_NOTICE</literal>,
104	<literal>LOG_INFO</literal>,
105	<literal>LOG_DEBUG</literal>, as defined in
106	<filename>syslog.h</filename>, see
107	<citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
108	for details. It is recommended to use this call to
109	submit log messages in the application locale or system
110	locale and in UTF-8 format, but no such restrictions
111	are enforced.</para>
112
113	<para><function>sd_journal_printv()</function> is
114	similar to <function>sd_journal_print()</function> but
115	takes a variable argument list encapsulated in an
116	object of type <literal>va_list</literal> (see
117	<citerefentry><refentrytitle>stdarg</refentrytitle><manvolnum>3</manvolnum></citerefentry>
118	for more information) instead of the format string. It
119	is otherwise equivalent in behaviour.</para>
120
121	<para><function>sd_journal_send()</function> may be
122	used to submit structured log entries to the system
123	journal. It takes a series of format strings, each
124	immediately followed by their associated parameters,
19125c20	125	terminated by NULL. The strings passed should be of
a8eedf49 LP	126	the format <literal>VARIABLE=value</literal>. The
	127	variable name must be in uppercase and consist only
	128	of characters, numbers and underscores, and may not
	129	begin with an underscore. The value can be of any size
	130	and format. It is highly recommended to submit
	131	text strings formatted in the UTF-8 character encoding
	132	only, and submit binary fields only when formatting in
	133	UTf-8 strings is not sensible. A number of well known
	134	fields are defined, see
	135	<citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
	136	for details, but additional application defined fields
	137	may be used.</para>
	138
	139	<para><function>sd_journal_sendv()</function> is
	140	similar to <function>sd_journal_send()</function> but
	141	takes an array of <literal>struct iovec</literal> (as
	142	defined in <filename>uio.h</filename>, see
	143	<citerefentry><refentrytitle>readv</refentrytitle><manvolnum>3</manvolnum></citerefentry>
	144	for details) instead of the format string. Each
	145	structure should reference one field of the entry to
	146	submit. The second argument specifies the number of
	147	structures in the
	148	array. <function>sd_journal_sendv()</function> is
	149	particularly useful to submit binary objects to the
	150	journal where that is necessary.</para>
	151
	152	<para>Note that <function>sd_journal_send()</function>
19125c20	153	is a wrapper around
a8eedf49 LP	154	<function>sd_journal_sendv()</function> to make it
	155	easier to use when only text strings shall be
	156	submitted. Also, the following two calls are
	157	mostly equivalent:</para>
	158
	159	<programlisting>sd_journal_print(LOG_INFO, "Hello World, this is PID %lu!", (unsigned long) getpid());
	160
	161	sd_journal_send("MESSAGE=Hello World, this is PID %lu!", (unsigned long) getpid(),
	162	"PRIORITY=%i", LOG_INFO,
	163	NULL);</programlisting>
	164
	165	<para>Note that these calls implicitly add fields for
	166	the source file, function name and code line where
	167	invoked. This is implemented with macros. If this is
	168	not desired it can be turned off by defining
	169	SD_JOURNAL_SUPPRESS_LOCATION before including
	170	<filename>sd-journal.h</filename>.</para>
6aae0ed2 LP	171
	172	<para><citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
	173	and and <function>sd_journal_print()</function> may
19125c20	174	largely be used interchangably
6aae0ed2 LP	175	functionality-wise. However, note that log messages
	176	logged via the former take a different path to the
	177	journal server than the later, and hence global
	178	chronological ordering between the two streams cannot
	179	be guaranteed. Using
	180	<function>sd_journal_print()</function> has the
	181	benefit of logging source code line, file names, and
	182	functions as meta data along all entries, and
	183	guaranteeing chronological ordering with structured
	184	log entries that are generated via
	185	<function>sd_journal_send()</function>. Using
	186	<function>syslog()</function> has the benefit of being
	187	more portable.</para>
a8eedf49 LP	188	</refsect1>
	189
	190	<refsect1>
	191	<title>Return Value</title>
	192
	193	<para>The four calls return 0 on success or a
	194	negative errno-style error code.</para>
	195	</refsect1>
	196
	197	<refsect1>
	198	<title>Notes</title>
	199
	200	<para>The <function>sd_journal_print()</function>,
	201	<function>sd_journal_printv()</function>,
	202	<function>sd_journal_send()</function> and
	203	<function>sd_journal_sendv()</function> interfaces
	204	are available as shared library, which can be compiled
	205	and linked to with the
	206	<literal>libsystemd-journal</literal>
	207	<citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
	208	file.</para>
	209	</refsect1>
	210
	211	<refsect1>
	212	<title>See Also</title>
	213
	214	<para>
	215	<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
cb07866b	216	<citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
a8eedf49 LP	217	<citerefentry><refentrytitle>sd_journal_stream_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
	218	<citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
	219	<citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
	220	</para>
	221	</refsect1>
	222
	223	</refentry>