]>
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, | |
125 | terminated by a NULL. The strings passed should be of | |
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> | |
153 | is a wapper around | |
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 | |
174 | mostly be used interchangably | |
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>, | |
216 | <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>7</manvolnum></citerefentry>, | |
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> |