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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> | |
976c46f8 | 50 | <refname>SD_JOURNAL_SUPPRESS_LOCATION</refname> |
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51 | <refpurpose>Submit log entries to the journal</refpurpose> |
52 | </refnamediv> | |
53 | ||
54 | <refsynopsisdiv> | |
55 | <funcsynopsis> | |
56 | <funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo> | |
57 | ||
58 | <funcprototype> | |
59 | <funcdef>int <function>sd_journal_print</function></funcdef> | |
60 | <paramdef>int <parameter>priority</parameter></paramdef> | |
61 | <paramdef>const char* <parameter>format</parameter></paramdef> | |
62 | <paramdef>...</paramdef> | |
63 | </funcprototype> | |
64 | ||
65 | <funcprototype> | |
66 | <funcdef>int <function>sd_journal_printv</function></funcdef> | |
67 | <paramdef>int <parameter>priority</parameter></paramdef> | |
68 | <paramdef>const char* <parameter>format</parameter></paramdef> | |
69 | <paramdef>va_list <parameter>ap</parameter></paramdef> | |
70 | </funcprototype> | |
71 | ||
72 | <funcprototype> | |
73 | <funcdef>int <function>sd_journal_send</function></funcdef> | |
74 | <paramdef>const char* <parameter>format</parameter></paramdef> | |
75 | <paramdef>...</paramdef> | |
76 | </funcprototype> | |
77 | ||
78 | <funcprototype> | |
79 | <funcdef>int <function>sd_journal_sendv</function></funcdef> | |
80 | <paramdef>const struct iovec *<parameter>iov</parameter></paramdef> | |
81 | <paramdef>int <parameter>n</parameter></paramdef> | |
82 | </funcprototype> | |
83 | ||
84 | </funcsynopsis> | |
85 | </refsynopsisdiv> | |
86 | ||
87 | <refsect1> | |
88 | <title>Description</title> | |
89 | ||
90 | <para><function>sd_journal_print()</function> may be | |
91 | used to submit simple, plain text log entries to the | |
92 | system journal. The first argument is a priority | |
93 | value. This is followed by a format string and its | |
94 | parameters, similar to | |
95 | <citerefentry><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
96 | or | |
97 | <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>. The | |
98 | priority value is one of | |
99 | <literal>LOG_EMERG</literal>, | |
100 | <literal>LOG_ALERT</literal>, | |
101 | <literal>LOG_CRIT</literal>, | |
102 | <literal>LOG_ERR</literal>, | |
103 | <literal>LOG_WARNING</literal>, | |
104 | <literal>LOG_NOTICE</literal>, | |
105 | <literal>LOG_INFO</literal>, | |
106 | <literal>LOG_DEBUG</literal>, as defined in | |
107 | <filename>syslog.h</filename>, see | |
108 | <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
109 | for details. It is recommended to use this call to | |
110 | submit log messages in the application locale or system | |
111 | locale and in UTF-8 format, but no such restrictions | |
112 | are enforced.</para> | |
113 | ||
114 | <para><function>sd_journal_printv()</function> is | |
115 | similar to <function>sd_journal_print()</function> but | |
116 | takes a variable argument list encapsulated in an | |
117 | object of type <literal>va_list</literal> (see | |
118 | <citerefentry><refentrytitle>stdarg</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
119 | for more information) instead of the format string. It | |
120 | is otherwise equivalent in behaviour.</para> | |
121 | ||
122 | <para><function>sd_journal_send()</function> may be | |
123 | used to submit structured log entries to the system | |
124 | journal. It takes a series of format strings, each | |
125 | immediately followed by their associated parameters, | |
19125c20 | 126 | terminated by NULL. The strings passed should be of |
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127 | the format <literal>VARIABLE=value</literal>. The |
128 | variable name must be in uppercase and consist only | |
129 | of characters, numbers and underscores, and may not | |
130 | begin with an underscore. The value can be of any size | |
131 | and format. It is highly recommended to submit | |
132 | text strings formatted in the UTF-8 character encoding | |
133 | only, and submit binary fields only when formatting in | |
134 | UTf-8 strings is not sensible. A number of well known | |
135 | fields are defined, see | |
136 | <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
137 | for details, but additional application defined fields | |
138 | may be used.</para> | |
139 | ||
140 | <para><function>sd_journal_sendv()</function> is | |
141 | similar to <function>sd_journal_send()</function> but | |
142 | takes an array of <literal>struct iovec</literal> (as | |
143 | defined in <filename>uio.h</filename>, see | |
144 | <citerefentry><refentrytitle>readv</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
145 | for details) instead of the format string. Each | |
146 | structure should reference one field of the entry to | |
147 | submit. The second argument specifies the number of | |
148 | structures in the | |
149 | array. <function>sd_journal_sendv()</function> is | |
150 | particularly useful to submit binary objects to the | |
151 | journal where that is necessary.</para> | |
152 | ||
153 | <para>Note that <function>sd_journal_send()</function> | |
19125c20 | 154 | is a wrapper around |
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155 | <function>sd_journal_sendv()</function> to make it |
156 | easier to use when only text strings shall be | |
157 | submitted. Also, the following two calls are | |
158 | mostly equivalent:</para> | |
159 | ||
160 | <programlisting>sd_journal_print(LOG_INFO, "Hello World, this is PID %lu!", (unsigned long) getpid()); | |
161 | ||
162 | sd_journal_send("MESSAGE=Hello World, this is PID %lu!", (unsigned long) getpid(), | |
163 | "PRIORITY=%i", LOG_INFO, | |
164 | NULL);</programlisting> | |
165 | ||
166 | <para>Note that these calls implicitly add fields for | |
167 | the source file, function name and code line where | |
168 | invoked. This is implemented with macros. If this is | |
169 | not desired it can be turned off by defining | |
170 | SD_JOURNAL_SUPPRESS_LOCATION before including | |
171 | <filename>sd-journal.h</filename>.</para> | |
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172 | |
173 | <para><citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
174 | and and <function>sd_journal_print()</function> may | |
49f43d5f | 175 | largely be used interchangeably |
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176 | functionality-wise. However, note that log messages |
177 | logged via the former take a different path to the | |
178 | journal server than the later, and hence global | |
179 | chronological ordering between the two streams cannot | |
180 | be guaranteed. Using | |
181 | <function>sd_journal_print()</function> has the | |
182 | benefit of logging source code line, file names, and | |
183 | functions as meta data along all entries, and | |
184 | guaranteeing chronological ordering with structured | |
185 | log entries that are generated via | |
186 | <function>sd_journal_send()</function>. Using | |
187 | <function>syslog()</function> has the benefit of being | |
188 | more portable.</para> | |
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189 | </refsect1> |
190 | ||
191 | <refsect1> | |
192 | <title>Return Value</title> | |
193 | ||
194 | <para>The four calls return 0 on success or a | |
195 | negative errno-style error code.</para> | |
196 | </refsect1> | |
197 | ||
198 | <refsect1> | |
199 | <title>Notes</title> | |
200 | ||
201 | <para>The <function>sd_journal_print()</function>, | |
202 | <function>sd_journal_printv()</function>, | |
203 | <function>sd_journal_send()</function> and | |
204 | <function>sd_journal_sendv()</function> interfaces | |
205 | are available as shared library, which can be compiled | |
206 | and linked to with the | |
207 | <literal>libsystemd-journal</literal> | |
208 | <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
209 | file.</para> | |
210 | </refsect1> | |
211 | ||
212 | <refsect1> | |
213 | <title>See Also</title> | |
214 | ||
215 | <para> | |
216 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
cb07866b | 217 | <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
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218 | <citerefentry><refentrytitle>sd_journal_stream_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
219 | <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
220 | <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
221 | </para> | |
222 | </refsect1> | |
223 | ||
224 | </refentry> |