1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
|
<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
<refentry id="sd_journal_print" xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>sd_journal_print</title>
<productname>systemd</productname>
</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>
<refname>sd_journal_perror</refname>
<refname>SD_JOURNAL_SUPPRESS_LOCATION</refname>
<refname>sd_journal_print_with_location</refname>
<refname>sd_journal_printv_with_location</refname>
<refname>sd_journal_send_with_location</refname>
<refname>sd_journal_sendv_with_location</refname>
<refname>sd_journal_perror_with_location</refname>
<refpurpose>Submit log entries to the journal</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include <systemd/sd-journal.h></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>
<funcprototype>
<funcdef>int <function>sd_journal_perror</function></funcdef>
<paramdef>const char *<parameter>message</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_journal_print_with_location</function></funcdef>
<paramdef>int <parameter>priority</parameter></paramdef>
<paramdef>const char *<parameter>file</parameter></paramdef>
<paramdef>const char *<parameter>line</parameter></paramdef>
<paramdef>const char *<parameter>func</parameter></paramdef>
<paramdef>const char *<parameter>format</parameter></paramdef>
<paramdef>…</paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_journal_printv_with_location</function></funcdef>
<paramdef>int <parameter>priority</parameter></paramdef>
<paramdef>const char *<parameter>file</parameter></paramdef>
<paramdef>const char *<parameter>line</parameter></paramdef>
<paramdef>const char *<parameter>func</parameter></paramdef>
<paramdef>const char *<parameter>format</parameter></paramdef>
<paramdef>va_list <parameter>ap</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_journal_send_with_location</function></funcdef>
<paramdef>const char *<parameter>file</parameter></paramdef>
<paramdef>const char *<parameter>line</parameter></paramdef>
<paramdef>const char *<parameter>func</parameter></paramdef>
<paramdef>const char *<parameter>format</parameter></paramdef>
<paramdef>…</paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_journal_sendv_with_location</function></funcdef>
<paramdef>const char *<parameter>file</parameter></paramdef>
<paramdef>const char *<parameter>line</parameter></paramdef>
<paramdef>const char *<parameter>func</parameter></paramdef>
<paramdef>const struct iovec *<parameter>iov</parameter></paramdef>
<paramdef>int <parameter>n</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_journal_perror_with_location</function></funcdef>
<paramdef>const char *<parameter>file</parameter></paramdef>
<paramdef>const char *<parameter>line</parameter></paramdef>
<paramdef>const char *<parameter>func</parameter></paramdef>
<paramdef>const char *<parameter>message</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 project='man-pages'><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry> or
<citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
Note that currently the resulting message will be truncated to <constant>LINE_MAX - 8</constant>.
The priority value is one of <constant>LOG_EMERG</constant>, <constant>LOG_ALERT</constant>,
<constant>LOG_CRIT</constant>, <constant>LOG_ERR</constant>, <constant>LOG_WARNING</constant>,
<constant>LOG_NOTICE</constant>, <constant>LOG_INFO</constant>, <constant>LOG_DEBUG</constant>, as defined in
<filename>syslog.h</filename>, see <citerefentry
project='man-pages'><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. Note that log messages written using this function are generally not
expected to end in a new-line character. However, as all trailing whitespace (including spaces, new-lines,
tabulators and carriage returns) are automatically stripped from the logged string, it is acceptable to specify one
(or more). Empty lines (after trailing whitespace removal) are suppressed. On non-empty lines, leading whitespace
(as well as inner whitespace) is left unmodified. </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
<varname>va_list</varname> (see
<citerefentry project='man-pages'><refentrytitle>stdarg</refentrytitle><manvolnum>3</manvolnum></citerefentry>
for more information) instead of the format string. It is
otherwise equivalent in behavior.</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
<constant>NULL</constant>. 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. (All assignments that do not follow this syntax will be ignored.) 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. A variable may be assigned more than one value per
entry. If this function is used, trailing whitespace is automatically removed from each formatted field.</para>
<para><function>sd_journal_sendv()</function> is similar to <function>sd_journal_send()</function> but takes an
array of <varname>struct iovec</varname> (as defined in <filename>uio.h</filename>, see <citerefentry
project='man-pages'><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. Note that this function will not strip trailing
whitespace of the passed fields, but passes the specified data along unmodified. This is different from both
<function>sd_journal_print()</function> and <function>sd_journal_send()</function> described above, which are based
on format strings, and do strip trailing whitespace.</para>
<para><function>sd_journal_perror()</function> is a similar to
<citerefentry project='die-net'><refentrytitle>perror</refentrytitle><manvolnum>3</manvolnum></citerefentry>
and writes a message to the journal that consists of the passed
string, suffixed with ": " and a human-readable representation of
the current error code stored in
<citerefentry project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
If the message string is passed as <constant>NULL</constant> or
empty string, only the error string representation will be
written, prefixed with nothing. An additional journal field ERRNO=
is included in the entry containing the numeric error code
formatted as decimal string. The log priority used is
<constant>LOG_ERR</constant> (3).</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
<constant>SD_JOURNAL_SUPPRESS_LOCATION</constant> before including <filename>sd-journal.h</filename>.
</para>
<para><function>sd_journal_print_with_location()</function>,
<function>sd_journal_printv_with_location()</function>, <function>sd_journal_send_with_location()</function>,
<function>sd_journal_sendv_with_location()</function>, and
<function>sd_journal_perror_with_location()</function> are similar to their counterparts without
<literal>_with_location</literal>, but accept additional parameters to explicitly set the source file
name, function, and line. The arguments <literal>file</literal> and <literal>line</literal> must contain valid
journal entries including the variable name, e.g. <literal>CODE_FILE=src/foo.c</literal> and
<literal>CODE_LINE=666</literal>, while <literal>func</literal> must only contain the function name, i.e. the value
without <literal>CODE_FUNC=</literal>. These variants are primarily useful when writing custom wrappers, for
example in bindings for a different language.</para>
<para><citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
and <function>sd_journal_print()</function> may
largely be used interchangeably
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, filenames, and
functions as metadata 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>
<para>These functions implement a client to the <ulink
url="https://systemd.io/JOURNAL_NATIVE_PROTOCOL">Native Journal Protocol</ulink>.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>The ten functions return 0 on success or a negative errno-style error code. The
<citerefentry project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>
variable itself is not altered.</para>
<para>If
<citerefentry><refentrytitle>systemd-journald</refentrytitle><manvolnum>8</manvolnum></citerefentry>
is not running (the socket is not present), those functions do
nothing, and also return 0.</para>
</refsect1>
<refsect1>
<title>Thread safety</title>
<xi:include href="threads-aware.xml" xpointer="safe"/>
<para><function>sd_journal_sendv()</function> and <function>sd_journal_sendv_with_location()</function>
are "async signal safe" in the meaning of
<citerefentry project='man-pages'><refentrytitle>signal-safety</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
</para>
<para><function>sd_journal_print()</function>,
<function>sd_journal_printv()</function>,
<function>sd_journal_send()</function>,
<function>sd_journal_perror()</function>,
and their counterparts with <literal>_with_location</literal>
are not async signal safe.</para>
</refsect1>
<xi:include href="libsystemd-pkgconfig.xml" />
<refsect1>
<title>History</title>
<para><function>sd_journal_print()</function>,
<function>sd_journal_printv()</function>,
<function>sd_journal_send()</function>, and
<function>sd_journal_sendv()</function> were added in version 187.</para>
<para><function>sd_journal_perror()</function> was added in version 188.</para>
<para><function>sd_journal_print_with_location()</function>,
<function>sd_journal_printv_with_location()</function>,
<function>sd_journal_send_with_location()</function>,
<function>sd_journal_sendv_with_location()</function>, and
<function>sd_journal_perror_with_location()</function> were added in version 246.</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para><simplelist type="inline">
<member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>sd_journal_stream_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
<member><citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
<member><citerefentry project='die-net'><refentrytitle>perror</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
<member><citerefentry project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
<member><citerefentry project='man-pages'><refentrytitle>signal</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
<member><citerefentry project='man-pages'><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
</simplelist></para>
</refsect1>
</refentry>
|
