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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_stream_fd"> | |
25 | ||
26 | <refentryinfo> | |
27 | <title>sd_journal_stream_fd</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_stream_fd</refentrytitle> | |
42 | <manvolnum>3</manvolnum> | |
43 | </refmeta> | |
44 | ||
45 | <refnamediv> | |
46 | <refname>sd_journal_stream_fd</refname> | |
47 | <refpurpose>Create log stream file descriptor to the journal</refpurpose> | |
48 | </refnamediv> | |
49 | ||
50 | <refsynopsisdiv> | |
51 | <funcsynopsis> | |
52 | <funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo> | |
53 | ||
54 | <funcprototype> | |
55 | <funcdef>int <function>sd_journal_stream_fd</function></funcdef> | |
60f067b4 | 56 | <paramdef>const char *<parameter>identifier</parameter></paramdef> |
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57 | <paramdef>int <parameter>priority</parameter></paramdef> |
58 | <paramdef>int <parameter>level_prefix</parameter></paramdef> | |
59 | </funcprototype> | |
60 | ||
61 | </funcsynopsis> | |
62 | </refsynopsisdiv> | |
63 | ||
64 | <refsect1> | |
65 | <title>Description</title> | |
66 | ||
67 | <para><function>sd_journal_stream_fd()</function> may | |
68 | be used to create a log stream file descriptor. Log | |
69 | messages written to this file descriptor as simple | |
14228c0d | 70 | newline-separated text strings are written to the |
663996b3 | 71 | journal. This file descriptor can be used internally |
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72 | by applications or be made standard output or standard |
73 | error of other processes executed.</para> | |
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74 | |
75 | <para><function>sd_journal_stream_fd()</function> | |
76 | takes a short program identifier string as first | |
77 | argument, which will be written to the journal as | |
78 | _SYSLOG_IDENTIFIER= field for each log entry (see | |
79 | <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
80 | for more information). The second argument shall be | |
81 | the default priority level for all messages. The | |
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82 | priority level is one of <constant>LOG_EMERG</constant>, |
83 | <constant>LOG_ALERT</constant>, | |
84 | <constant>LOG_CRIT</constant>, | |
85 | <constant>LOG_ERR</constant>, | |
86 | <constant>LOG_WARNING</constant>, | |
87 | <constant>LOG_NOTICE</constant>, | |
88 | <constant>LOG_INFO</constant>, | |
89 | <constant>LOG_DEBUG</constant>, as defined in | |
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90 | <filename>syslog.h</filename>, see |
91 | <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
92 | for details. The third argument is a boolean: if true | |
93 | kernel-style log priority level prefixes (such as | |
14228c0d | 94 | <constant>SD_WARNING</constant>) are interpreted, see |
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95 | <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry> |
96 | for more information.</para> | |
97 | ||
98 | <para>It is recommended that applications log UTF-8 | |
99 | messages only with this API, but this is not | |
100 | enforced.</para> | |
101 | ||
102 | </refsect1> | |
103 | ||
104 | <refsect1> | |
105 | <title>Return Value</title> | |
106 | ||
107 | <para>The call returns a valid write-only file descriptor on success or a | |
108 | negative errno-style error code.</para> | |
109 | </refsect1> | |
110 | ||
111 | <refsect1> | |
112 | <title>Notes</title> | |
113 | ||
114 | <para>The <function>sd_journal_stream_fd()</function> | |
60f067b4 | 115 | interface is available as a shared library, which can |
663996b3 | 116 | be compiled and linked to with the |
60f067b4 | 117 | <constant>libsystemd</constant> <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> |
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118 | file.</para> |
119 | </refsect1> | |
120 | ||
121 | <refsect1> | |
122 | <title>Examples</title> | |
123 | ||
124 | <para>Creating a log stream suitable for | |
125 | <citerefentry><refentrytitle>fprintf</refentrytitle><manvolnum>3</manvolnum></citerefentry>:</para> | |
126 | ||
127 | <programlisting>#include <syslog.h> | |
128 | #include <stdio.h> | |
129 | #include <string.h> | |
130 | #include <unistd.h> | |
131 | #include <systemd/sd-journal.h> | |
132 | #include <systemd/sd-daemon.h> | |
133 | ||
134 | int main(int argc, char *argv[]) { | |
135 | int fd; | |
136 | FILE *log; | |
137 | fd = sd_journal_stream_fd("test", LOG_INFO, 1); | |
138 | if (fd < 0) { | |
139 | fprintf(stderr, "Failed to create stream fd: %s\n", strerror(-fd)); | |
140 | return 1; | |
141 | } | |
142 | log = fdopen(fd, "w"); | |
143 | if (!log) { | |
144 | fprintf(stderr, "Failed to create file object: %m\n"); | |
145 | close(fd); | |
146 | return 1; | |
147 | } | |
148 | fprintf(log, "Hello World!\n"); | |
149 | fprintf(log, SD_WARNING "This is a warning!\n"); | |
150 | fclose(log); | |
151 | return 0; | |
152 | }</programlisting> | |
153 | ||
154 | </refsect1> | |
155 | ||
156 | <refsect1> | |
157 | <title>See Also</title> | |
158 | ||
159 | <para> | |
160 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
161 | <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
162 | <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
163 | <citerefentry><refentrytitle>sd_journal_print</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
164 | <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
165 | <citerefentry><refentrytitle>fprintf</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
166 | <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
167 | </para> | |
168 | </refsect1> | |
169 | ||
170 | </refentry> |