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a81df0ad | 1 | <?xml version='1.0'?> <!--*-nxml-*--> |
3a54a157 | 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
eea10b26 | 3 | "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd"> |
db9ecf05 | 4 | <!-- SPDX-License-Identifier: LGPL-2.1-or-later --> |
a81df0ad | 5 | |
7d6b2723 | 6 | <refentry id="sd_journal_stream_fd" xmlns:xi="http://www.w3.org/2001/XInclude"> |
a81df0ad | 7 | |
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8 | <refentryinfo> |
9 | <title>sd_journal_stream_fd</title> | |
10 | <productname>systemd</productname> | |
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11 | </refentryinfo> |
12 | ||
13 | <refmeta> | |
14 | <refentrytitle>sd_journal_stream_fd</refentrytitle> | |
15 | <manvolnum>3</manvolnum> | |
16 | </refmeta> | |
17 | ||
18 | <refnamediv> | |
19 | <refname>sd_journal_stream_fd</refname> | |
32104d32 | 20 | <refname>sd_journal_stream_fd_with_namespace</refname> |
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21 | <refpurpose>Create log stream file descriptor to the journal</refpurpose> |
22 | </refnamediv> | |
23 | ||
24 | <refsynopsisdiv> | |
25 | <funcsynopsis> | |
26 | <funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo> | |
27 | ||
28 | <funcprototype> | |
29 | <funcdef>int <function>sd_journal_stream_fd</function></funcdef> | |
30 | <paramdef>const char *<parameter>identifier</parameter></paramdef> | |
31 | <paramdef>int <parameter>priority</parameter></paramdef> | |
32 | <paramdef>int <parameter>level_prefix</parameter></paramdef> | |
33 | </funcprototype> | |
34 | ||
32104d32 MY |
35 | <funcprototype> |
36 | <funcdef>int <function>sd_journal_stream_fd_with_namespace</function></funcdef> | |
37 | <paramdef>const char *<parameter>name_space</parameter></paramdef> | |
38 | <paramdef>const char *<parameter>identifier</parameter></paramdef> | |
39 | <paramdef>int <parameter>priority</parameter></paramdef> | |
40 | <paramdef>int <parameter>level_prefix</parameter></paramdef> | |
41 | </funcprototype> | |
42 | ||
798d3a52 ZJS |
43 | </funcsynopsis> |
44 | </refsynopsisdiv> | |
45 | ||
46 | <refsect1> | |
47 | <title>Description</title> | |
48 | ||
32104d32 MY |
49 | <para><function>sd_journal_stream_fd()</function> may be used to create a log stream file descriptor. |
50 | Log messages written to this file descriptor as simple newline-separated text strings are written | |
51 | to the journal. This file descriptor can be used internally by applications or be made standard output | |
52 | or standard error of other processes executed.</para> | |
798d3a52 | 53 | |
32104d32 MY |
54 | <para><function>sd_journal_stream_fd()</function> takes a short program identifier string as |
55 | first argument, which will be written to the journal as SYSLOG_IDENTIFIER= field for each log entry | |
798d3a52 ZJS |
56 | (see |
57 | <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
32104d32 MY |
58 | for more information). The second argument shall be the default priority level for all messages. |
59 | The priority level is one of | |
798d3a52 ZJS |
60 | <constant>LOG_EMERG</constant>, <constant>LOG_ALERT</constant>, |
61 | <constant>LOG_CRIT</constant>, <constant>LOG_ERR</constant>, | |
62 | <constant>LOG_WARNING</constant>, <constant>LOG_NOTICE</constant>, | |
63 | <constant>LOG_INFO</constant>, <constant>LOG_DEBUG</constant>, as | |
64 | defined in <filename>syslog.h</filename>, see | |
65 | <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
66 | for details. The third argument is a boolean: if true kernel-style | |
67 | log level prefixes (such as <constant>SD_WARNING</constant>) are | |
68 | interpreted, see | |
69 | <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
70 | for more information.</para> | |
71 | ||
32104d32 MY |
72 | <para><function>sd_journal_stream_fd_with_namespace()</function> is similar to |
73 | <function>sd_journal_stream_fd()</function>, but takes an additional <parameter>name_space</parameter> parameter | |
74 | that specifies which journal namespace to operate on. If specified as <constant>NULL</constant> the call | |
75 | is identical to <function>sd_journal_stream_fd()</function>. For details about journal namespaces, see | |
76 | <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para> | |
77 | ||
78 | <para>It is recommended that applications log UTF-8 messages only with this API, but this is not enforced.</para> | |
5b7e1d8e | 79 | |
32104d32 MY |
80 | <para>Each invocation of these functions allocates a new log stream file descriptor, |
81 | that is not shared with prior or later invocations. The file descriptor is write-only (its reading direction | |
82 | is shut down), and <constant>O_NONBLOCK</constant> is turned off initially.</para> | |
798d3a52 ZJS |
83 | </refsect1> |
84 | ||
85 | <refsect1> | |
86 | <title>Return Value</title> | |
87 | ||
32104d32 | 88 | <para>The call returns a valid write-only file descriptor on success or a negative errno-style error code.</para> |
798d3a52 ZJS |
89 | </refsect1> |
90 | ||
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91 | <refsect1> |
92 | <title>Signal safety</title> | |
93 | ||
32104d32 MY |
94 | <para><function>sd_journal_stream_fd()</function> and <function>sd_journal_stream_fd_with_namespace()</function> |
95 | are "async signal safe" in the meaning of <citerefentry | |
2695b872 | 96 | project='man-pages'><refentrytitle>signal-safety</refentrytitle><manvolnum>7</manvolnum></citerefentry>. |
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97 | </para> |
98 | </refsect1> | |
99 | ||
798d3a52 ZJS |
100 | <refsect1> |
101 | <title>Notes</title> | |
102 | ||
64a7ef8b | 103 | <xi:include href="threads-aware.xml" xpointer="safe"/> |
a8d46a16 | 104 | |
7d6b2723 | 105 | <xi:include href="libsystemd-pkgconfig.xml" xpointer="pkgconfig-text"/> |
798d3a52 ZJS |
106 | </refsect1> |
107 | ||
108 | <refsect1> | |
109 | <title>Examples</title> | |
110 | ||
111 | <para>Creating a log stream suitable for | |
112 | <citerefentry project='man-pages'><refentrytitle>fprintf</refentrytitle><manvolnum>3</manvolnum></citerefentry>:</para> | |
113 | ||
29c45dc4 | 114 | <programlisting><xi:include href="journal-stream-fd.c" parse="text" /></programlisting> |
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115 | </refsect1> |
116 | ||
69106f47 AK |
117 | <refsect1> |
118 | <title>History</title> | |
119 | <para><function>sd_journal_stream_fd()</function> was added in version 187.</para> | |
32104d32 | 120 | <para><function>sd_journal_stream_fd_with_namespace()</function> was added in version 256.</para> |
69106f47 AK |
121 | </refsect1> |
122 | ||
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123 | <refsect1> |
124 | <title>See Also</title> | |
125 | ||
13a69c12 DT |
126 | <para><simplelist type="inline"> |
127 | <member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member> | |
128 | <member><citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> | |
129 | <member><citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> | |
130 | <member><citerefentry><refentrytitle>sd_journal_print</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> | |
131 | <member><citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> | |
132 | <member><citerefentry project='man-pages'><refentrytitle>fprintf</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> | |
133 | <member><citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry></member> | |
134 | </simplelist></para> | |
798d3a52 | 135 | </refsect1> |
a81df0ad LP |
136 | |
137 | </refentry> |