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a8eedf49 | 1 | <?xml version='1.0'?> <!--*-nxml-*--> |
3a54a157 | 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
12b42c76 | 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
0307f791 | 4 | <!-- SPDX-License-Identifier: LGPL-2.1+ --> |
a8eedf49 | 5 | |
7d6b2723 | 6 | <refentry id="sd_journal_print" xmlns:xi="http://www.w3.org/2001/XInclude"> |
a8eedf49 | 7 | |
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8 | <refentryinfo> |
9 | <title>sd_journal_print</title> | |
10 | <productname>systemd</productname> | |
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11 | </refentryinfo> |
12 | ||
13 | <refmeta> | |
14 | <refentrytitle>sd_journal_print</refentrytitle> | |
15 | <manvolnum>3</manvolnum> | |
16 | </refmeta> | |
17 | ||
18 | <refnamediv> | |
19 | <refname>sd_journal_print</refname> | |
20 | <refname>sd_journal_printv</refname> | |
21 | <refname>sd_journal_send</refname> | |
22 | <refname>sd_journal_sendv</refname> | |
23 | <refname>sd_journal_perror</refname> | |
24 | <refname>SD_JOURNAL_SUPPRESS_LOCATION</refname> | |
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25 | <refname>sd_journal_print_with_location</refname> |
26 | <refname>sd_journal_printv_with_location</refname> | |
27 | <refname>sd_journal_send_with_location</refname> | |
28 | <refname>sd_journal_sendv_with_location</refname> | |
29 | <refname>sd_journal_perror_with_location</refname> | |
30 | ||
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31 | <refpurpose>Submit log entries to the journal</refpurpose> |
32 | </refnamediv> | |
33 | ||
34 | <refsynopsisdiv> | |
35 | <funcsynopsis> | |
36 | <funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo> | |
37 | ||
38 | <funcprototype> | |
39 | <funcdef>int <function>sd_journal_print</function></funcdef> | |
40 | <paramdef>int <parameter>priority</parameter></paramdef> | |
41 | <paramdef>const char *<parameter>format</parameter></paramdef> | |
1eecafb8 | 42 | <paramdef>…</paramdef> |
798d3a52 ZJS |
43 | </funcprototype> |
44 | ||
45 | <funcprototype> | |
46 | <funcdef>int <function>sd_journal_printv</function></funcdef> | |
47 | <paramdef>int <parameter>priority</parameter></paramdef> | |
48 | <paramdef>const char *<parameter>format</parameter></paramdef> | |
49 | <paramdef>va_list <parameter>ap</parameter></paramdef> | |
50 | </funcprototype> | |
51 | ||
52 | <funcprototype> | |
53 | <funcdef>int <function>sd_journal_send</function></funcdef> | |
54 | <paramdef>const char *<parameter>format</parameter></paramdef> | |
1eecafb8 | 55 | <paramdef>…</paramdef> |
798d3a52 ZJS |
56 | </funcprototype> |
57 | ||
58 | <funcprototype> | |
59 | <funcdef>int <function>sd_journal_sendv</function></funcdef> | |
60 | <paramdef>const struct iovec *<parameter>iov</parameter></paramdef> | |
61 | <paramdef>int <parameter>n</parameter></paramdef> | |
62 | </funcprototype> | |
63 | ||
64 | <funcprototype> | |
65 | <funcdef>int <function>sd_journal_perror</function></funcdef> | |
66 | <paramdef>const char *<parameter>message</parameter></paramdef> | |
67 | </funcprototype> | |
68 | ||
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69 | <funcprototype> |
70 | <funcdef>int <function>sd_journal_print_with_location</function></funcdef> | |
71 | <paramdef>const char *<parameter>file</parameter></paramdef> | |
72 | <paramdef>const char *<parameter>line</parameter></paramdef> | |
73 | <paramdef>const char *<parameter>func</parameter></paramdef> | |
74 | <paramdef>int <parameter>priority</parameter></paramdef> | |
75 | <paramdef>const char *<parameter>format</parameter></paramdef> | |
76 | <paramdef>…</paramdef> | |
77 | </funcprototype> | |
78 | ||
79 | <funcprototype> | |
80 | <funcdef>int <function>sd_journal_printv_with_location</function></funcdef> | |
81 | <paramdef>int <parameter>priority</parameter></paramdef> | |
82 | <paramdef>const char *<parameter>file</parameter></paramdef> | |
83 | <paramdef>const char *<parameter>line</parameter></paramdef> | |
84 | <paramdef>const char *<parameter>func</parameter></paramdef> | |
85 | <paramdef>const char *<parameter>format</parameter></paramdef> | |
86 | <paramdef>va_list <parameter>ap</parameter></paramdef> | |
87 | </funcprototype> | |
88 | ||
89 | <funcprototype> | |
90 | <funcdef>int <function>sd_journal_send_with_location</function></funcdef> | |
91 | <paramdef>const char *<parameter>file</parameter></paramdef> | |
92 | <paramdef>const char *<parameter>line</parameter></paramdef> | |
93 | <paramdef>const char *<parameter>func</parameter></paramdef> | |
94 | <paramdef>const char *<parameter>format</parameter></paramdef> | |
95 | <paramdef>…</paramdef> | |
96 | </funcprototype> | |
97 | ||
98 | <funcprototype> | |
99 | <funcdef>int <function>sd_journal_sendv_with_location</function></funcdef> | |
100 | <paramdef>const char *<parameter>file</parameter></paramdef> | |
101 | <paramdef>const char *<parameter>line</parameter></paramdef> | |
102 | <paramdef>const char *<parameter>func</parameter></paramdef> | |
103 | <paramdef>const struct iovec *<parameter>iov</parameter></paramdef> | |
104 | <paramdef>int <parameter>n</parameter></paramdef> | |
105 | </funcprototype> | |
106 | ||
107 | <funcprototype> | |
108 | <funcdef>int <function>sd_journal_perror_with_location</function></funcdef> | |
109 | <paramdef>const char *<parameter>file</parameter></paramdef> | |
110 | <paramdef>const char *<parameter>line</parameter></paramdef> | |
111 | <paramdef>const char *<parameter>func</parameter></paramdef> | |
112 | <paramdef>const char *<parameter>message</parameter></paramdef> | |
113 | </funcprototype> | |
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114 | </funcsynopsis> |
115 | </refsynopsisdiv> | |
116 | ||
117 | <refsect1> | |
118 | <title>Description</title> | |
119 | ||
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120 | <para><function>sd_journal_print()</function> may be used to submit simple, plain text log entries to the system |
121 | journal. The first argument is a priority value. This is followed by a format string and its parameters, similar to | |
122 | <citerefentry project='man-pages'><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry> or | |
798d3a52 | 123 | <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>. |
11fcfc53 | 124 | Note that currently the resulting message will be truncated to <constant>LINE_MAX - 8</constant>. |
4c5db93f LP |
125 | The priority value is one of <constant>LOG_EMERG</constant>, <constant>LOG_ALERT</constant>, |
126 | <constant>LOG_CRIT</constant>, <constant>LOG_ERR</constant>, <constant>LOG_WARNING</constant>, | |
127 | <constant>LOG_NOTICE</constant>, <constant>LOG_INFO</constant>, <constant>LOG_DEBUG</constant>, as defined in | |
128 | <filename>syslog.h</filename>, see <citerefentry | |
129 | project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> for details. It is | |
130 | recommended to use this call to submit log messages in the application locale or system locale and in UTF-8 format, | |
131 | but no such restrictions are enforced. Note that log messages written using this function are generally not | |
132 | expected to end in a new-line character. However, as all trailing whitespace (including spaces, new-lines, | |
133 | tabulators and carriage returns) are automatically stripped from the logged string, it is acceptable to specify one | |
0d23bc57 LP |
134 | (or more). Empty lines (after trailing whitespace removal) are suppressed. On non-empty lines, leading whitespace |
135 | (as well as inner whitespace) is left unmodified. </para> | |
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136 | |
137 | <para><function>sd_journal_printv()</function> is similar to | |
138 | <function>sd_journal_print()</function> but takes a variable | |
139 | argument list encapsulated in an object of type | |
140 | <varname>va_list</varname> (see | |
3ba3a79d | 141 | <citerefentry project='man-pages'><refentrytitle>stdarg</refentrytitle><manvolnum>3</manvolnum></citerefentry> |
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142 | for more information) instead of the format string. It is |
143 | otherwise equivalent in behavior.</para> | |
144 | ||
4c5db93f LP |
145 | <para><function>sd_journal_send()</function> may be used to submit structured log entries to the system journal. It |
146 | takes a series of format strings, each immediately followed by their associated parameters, terminated by | |
147 | <constant>NULL</constant>. The strings passed should be of the format <literal>VARIABLE=value</literal>. The | |
148 | variable name must be in uppercase and consist only of characters, numbers and underscores, and may not begin with | |
149 | an underscore. (All assignments that do not follow this syntax will be ignored.) The value can be of any size and | |
150 | format. It is highly recommended to submit text strings formatted in the UTF-8 character encoding only, and submit | |
151 | binary fields only when formatting in UTF-8 strings is not sensible. A number of well-known fields are defined, see | |
152 | <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry> for | |
153 | details, but additional application defined fields may be used. A variable may be assigned more than one value per | |
154 | entry. If this function is used, trailing whitespace is automatically removed from each formatted field.</para> | |
155 | ||
156 | <para><function>sd_journal_sendv()</function> is similar to <function>sd_journal_send()</function> but takes an | |
157 | array of <varname>struct iovec</varname> (as defined in <filename>uio.h</filename>, see <citerefentry | |
158 | project='man-pages'><refentrytitle>readv</refentrytitle><manvolnum>3</manvolnum></citerefentry> for details) | |
159 | instead of the format string. Each structure should reference one field of the entry to submit. The second argument | |
160 | specifies the number of structures in the array. <function>sd_journal_sendv()</function> is particularly useful to | |
301a21a8 | 161 | submit binary objects to the journal where that is necessary. Note that this function will not strip trailing |
4c5db93f LP |
162 | whitespace of the passed fields, but passes the specified data along unmodified. This is different from both |
163 | <function>sd_journal_print()</function> and <function>sd_journal_send()</function> described above, which are based | |
164 | on format strings, and do strip trailing whitespace.</para> | |
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165 | |
166 | <para><function>sd_journal_perror()</function> is a similar to | |
3ba3a79d | 167 | <citerefentry project='die-net'><refentrytitle>perror</refentrytitle><manvolnum>3</manvolnum></citerefentry> |
798d3a52 | 168 | and writes a message to the journal that consists of the passed |
b938cb90 | 169 | string, suffixed with ": " and a human-readable representation of |
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170 | the current error code stored in |
171 | <citerefentry project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>. | |
172 | If the message string is passed as <constant>NULL</constant> or | |
173 | empty string, only the error string representation will be | |
174 | written, prefixed with nothing. An additional journal field ERRNO= | |
175 | is included in the entry containing the numeric error code | |
176 | formatted as decimal string. The log priority used is | |
177 | <constant>LOG_ERR</constant> (3).</para> | |
178 | ||
179 | <para>Note that <function>sd_journal_send()</function> is a | |
180 | wrapper around <function>sd_journal_sendv()</function> to make it | |
181 | easier to use when only text strings shall be submitted. Also, the | |
182 | following two calls are mostly equivalent:</para> | |
183 | ||
184 | <programlisting>sd_journal_print(LOG_INFO, "Hello World, this is PID %lu!", (unsigned long) getpid()); | |
a8eedf49 LP |
185 | |
186 | sd_journal_send("MESSAGE=Hello World, this is PID %lu!", (unsigned long) getpid(), | |
4c5db93f LP |
187 | "PRIORITY=%i", LOG_INFO, |
188 | NULL);</programlisting> | |
798d3a52 | 189 | |
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190 | <para>Note that these calls implicitly add fields for the source file, function name and code line where |
191 | invoked. This is implemented with macros. If this is not desired, it can be turned off by defining | |
192 | <constant>SD_JOURNAL_SUPPRESS_LOCATION</constant> before including <filename>sd-journal.h</filename>. | |
193 | </para> | |
194 | ||
195 | <para><function>sd_journal_print_with_location</function>, | |
196 | <function>sd_journal_printv_with_location</function>, <function>sd_journal_send_with_location</function>, | |
197 | <function>sd_journal_sendv_with_location</function>, and | |
198 | <function>sd_journal_perror_with_location</function> are similar to their counterparts without | |
199 | <literal>_with_location</literal>, but accept additional parameters to explicitly set the source file | |
200 | name, function, and line. Those arguments must contain valid journal entries including the variable name, | |
201 | e.g. <literal>CODE_FILE=src/foo.c</literal>, <literal>CODE_LINE=666</literal>, | |
202 | <literal>CODE_FUNC=myfunc</literal>. These variants are primarily useful when writing custom wrappers, | |
203 | for example in bindings for a different language.</para> | |
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204 | |
205 | <para><citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
206 | and <function>sd_journal_print()</function> may | |
207 | largely be used interchangeably | |
208 | functionality-wise. However, note that log messages | |
209 | logged via the former take a different path to the | |
210 | journal server than the later, and hence global | |
211 | chronological ordering between the two streams cannot | |
212 | be guaranteed. Using | |
213 | <function>sd_journal_print()</function> has the | |
214 | benefit of logging source code line, filenames, and | |
215 | functions as metadata along all entries, and | |
216 | guaranteeing chronological ordering with structured | |
217 | log entries that are generated via | |
218 | <function>sd_journal_send()</function>. Using | |
219 | <function>syslog()</function> has the benefit of being | |
220 | more portable.</para> | |
221 | </refsect1> | |
222 | ||
223 | <refsect1> | |
224 | <title>Return Value</title> | |
225 | ||
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226 | <para>The ten functions return 0 on success or a negative errno-style error code. The |
227 | <citerefentry project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
228 | variable itself is not altered.</para> | |
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229 | |
230 | <para>If | |
231 | <citerefentry><refentrytitle>systemd-journald</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
232 | is not running (the socket is not present), those functions do | |
233 | nothing, and also return 0.</para> | |
234 | </refsect1> | |
235 | ||
236 | <refsect1> | |
a8d46a16 | 237 | <title>Thread safety</title> |
64a7ef8b LP |
238 | |
239 | <xi:include href="threads-aware.xml" xpointer="safe"/> | |
a8d46a16 | 240 | |
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241 | <para><function>sd_journal_sendv()</function> and <function>sd_journal_sendv_with_location()</function> |
242 | are "async signal safe" in the meaning of | |
243 | <citerefentry project='man-pages'><refentrytitle>signal-safety</refentrytitle><manvolnum>7</manvolnum></citerefentry>. | |
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244 | </para> |
245 | ||
246 | <para><function>sd_journal_print</function>, | |
247 | <function>sd_journal_printv</function>, | |
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248 | <function>sd_journal_send</function>, |
249 | <function>sd_journal_perror</function>, | |
250 | and their counterparts with <literal>_with_location</literal> | |
251 | are not async signal safe.</para> | |
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252 | </refsect1> |
253 | ||
7d6b2723 | 254 | <xi:include href="libsystemd-pkgconfig.xml" /> |
798d3a52 ZJS |
255 | |
256 | <refsect1> | |
257 | <title>See Also</title> | |
258 | ||
259 | <para> | |
260 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
261 | <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
262 | <citerefentry><refentrytitle>sd_journal_stream_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
263 | <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
3ba3a79d | 264 | <citerefentry project='die-net'><refentrytitle>perror</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
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265 | <citerefentry project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
266 | <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>, | |
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267 | <citerefentry project='man-pages'><refentrytitle>signal</refentrytitle><manvolnum>7</manvolnum></citerefentry>, |
268 | <citerefentry project='man-pages'><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
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269 | </para> |
270 | </refsect1> | |
a8eedf49 LP |
271 | |
272 | </refentry> |