mirror of
https://github.com/systemd/systemd.git
synced 2024-11-26 19:53:45 +08:00
138 lines
6.4 KiB
XML
138 lines
6.4 KiB
XML
<?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_stream_fd" xmlns:xi="http://www.w3.org/2001/XInclude">
|
|
|
|
<refentryinfo>
|
|
<title>sd_journal_stream_fd</title>
|
|
<productname>systemd</productname>
|
|
</refentryinfo>
|
|
|
|
<refmeta>
|
|
<refentrytitle>sd_journal_stream_fd</refentrytitle>
|
|
<manvolnum>3</manvolnum>
|
|
</refmeta>
|
|
|
|
<refnamediv>
|
|
<refname>sd_journal_stream_fd</refname>
|
|
<refname>sd_journal_stream_fd_with_namespace</refname>
|
|
<refpurpose>Create log stream file descriptor to the journal</refpurpose>
|
|
</refnamediv>
|
|
|
|
<refsynopsisdiv>
|
|
<funcsynopsis>
|
|
<funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo>
|
|
|
|
<funcprototype>
|
|
<funcdef>int <function>sd_journal_stream_fd</function></funcdef>
|
|
<paramdef>const char *<parameter>identifier</parameter></paramdef>
|
|
<paramdef>int <parameter>priority</parameter></paramdef>
|
|
<paramdef>int <parameter>level_prefix</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>int <function>sd_journal_stream_fd_with_namespace</function></funcdef>
|
|
<paramdef>const char *<parameter>name_space</parameter></paramdef>
|
|
<paramdef>const char *<parameter>identifier</parameter></paramdef>
|
|
<paramdef>int <parameter>priority</parameter></paramdef>
|
|
<paramdef>int <parameter>level_prefix</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
</funcsynopsis>
|
|
</refsynopsisdiv>
|
|
|
|
<refsect1>
|
|
<title>Description</title>
|
|
|
|
<para><function>sd_journal_stream_fd()</function> may be used to create a log stream file descriptor.
|
|
Log messages written to this file descriptor as simple newline-separated text strings are written
|
|
to the journal. This file descriptor can be used internally by applications or be made standard output
|
|
or standard error of other processes executed.</para>
|
|
|
|
<para><function>sd_journal_stream_fd()</function> takes a short program identifier string as
|
|
first argument, which will be written to the journal as SYSLOG_IDENTIFIER= field for each log entry
|
|
(see
|
|
<citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
|
|
for more information). The second argument shall be the default priority level for all messages.
|
|
The priority level 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. The third argument is a boolean: if true kernel-style
|
|
log level prefixes (such as <constant>SD_WARNING</constant>) are
|
|
interpreted, see
|
|
<citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
|
for more information.</para>
|
|
|
|
<para><function>sd_journal_stream_fd_with_namespace()</function> is similar to
|
|
<function>sd_journal_stream_fd()</function>, but takes an additional <parameter>name_space</parameter> parameter
|
|
that specifies which journal namespace to operate on. If specified as <constant>NULL</constant> the call
|
|
is identical to <function>sd_journal_stream_fd()</function>. For details about journal namespaces, see
|
|
<citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
|
|
|
|
<para>It is recommended that applications log UTF-8 messages only with this API, but this is not enforced.</para>
|
|
|
|
<para>Each invocation of these functions allocates a new log stream file descriptor,
|
|
that is not shared with prior or later invocations. The file descriptor is write-only (its reading direction
|
|
is shut down), and <constant>O_NONBLOCK</constant> is turned off initially.</para>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Return Value</title>
|
|
|
|
<para>The call returns a valid write-only file descriptor on success or a negative errno-style error code.</para>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Signal safety</title>
|
|
|
|
<para><function>sd_journal_stream_fd()</function> and <function>sd_journal_stream_fd_with_namespace()</function>
|
|
are "async signal safe" in the meaning of <citerefentry
|
|
project='man-pages'><refentrytitle>signal-safety</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
|
|
</para>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Notes</title>
|
|
|
|
<xi:include href="threads-aware.xml" xpointer="safe"/>
|
|
|
|
<xi:include href="libsystemd-pkgconfig.xml" xpointer="pkgconfig-text"/>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Examples</title>
|
|
|
|
<para>Creating a log stream suitable for
|
|
<citerefentry project='man-pages'><refentrytitle>fprintf</refentrytitle><manvolnum>3</manvolnum></citerefentry>:</para>
|
|
|
|
<programlisting><xi:include href="journal-stream-fd.c" parse="text" /></programlisting>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>History</title>
|
|
<para><function>sd_journal_stream_fd()</function> was added in version 187.</para>
|
|
<para><function>sd_journal_stream_fd_with_namespace()</function> was added in version 256.</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-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>sd_journal_print</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
|
|
<member><citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
|
|
<member><citerefentry project='man-pages'><refentrytitle>fprintf</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
|
|
</simplelist></para>
|
|
</refsect1>
|
|
|
|
</refentry>
|