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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"

"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

<refentry id="sd_journal_stream_fd">

<refentryinfo>

<title>sd_journal_stream_fd</title>

<productname>systemd</productname>

<authorgroup>

<author>

<contrib>Developer</contrib>

<firstname>Lennart</firstname>

<surname>Poettering</surname>

<email>lennart@poettering.net</email>

</author>

</authorgroup>

</refentryinfo>

<refmeta>

<refentrytitle>sd_journal_stream_fd</refentrytitle>

<manvolnum>3</manvolnum>

</refmeta>

<refnamediv>

<refname>sd_journal_stream_fd</refname>

<refpurpose>Create log stream file descriptor to the journal</refpurpose>

</refnamediv>

<refsynopsisdiv>

<funcsynopsis>

<funcsynopsisinfo>#include &lt;systemd/sd-journal.h&gt;</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>

</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 STDOUT/STDERR 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 <literal>LOG_EMERG</literal>,

<literal>LOG_ALERT</literal>,

<literal>LOG_CRIT</literal>,

<literal>LOG_ERR</literal>,

<literal>LOG_WARNING</literal>,

<literal>LOG_NOTICE</literal>,

<literal>LOG_INFO</literal>,

<literal>LOG_DEBUG</literal>, as defined in

<filename>syslog.h</filename>, see

<citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>

for details. The third argument is a boolean: if true

kernel-style log priority level prefixes (such as

<literal>SD_WARNING</literal>) are interpreted, see

<citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>

for more information.</para>

<para>It is recommended that applications log UTF-8

messages only with this API, but this is not

enforced.</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>Notes</title>

<para>The <function>sd_journal_stream_fd()</function>

interface is available as shared library, which can

be compiled and linked to with the

<literal>libsystemd-journal</literal>

<citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>

file.</para>

</refsect1>

<refsect1>

<title>Examples</title>

<para>Creating a log stream suitable for

<citerefentry><refentrytitle>fprintf</refentrytitle><manvolnum>3</manvolnum></citerefentry>:</para>

<programlisting>#include &lt;syslog.h&gt;

#include &lt;stdio.h&gt;

#include &lt;string.h&gt;

#include &lt;unistd.h&gt;

#include &lt;systemd/sd-journal.h&gt;

#include &lt;systemd/sd-daemon.h&gt;

int main(int argc, char *argv[]) {

int fd;

FILE *log;

fd = sd_journal_stream_fd("test", LOG_INFO, 1);

if (fd &lt; 0) {

fprintf(stderr, "Failed to create stream fd: %s\n", strerror(-fd));

return 1;

}

log = fdopen(fd, "w");

if (!log) {

fprintf(stderr, "Failed to create file object: %m\n");

close(fd);

return 1;

}

fprintf(log, "Hello World!\n");

fprintf(log, SD_WARNING "This is a warning!\n");

fclose(log);

return 0;

}</programlisting>

</refsect1>

<refsect1>

<title>See Also</title>

<para>

<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,

<citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,

<citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>,

<citerefentry><refentrytitle>sd_journal_print</refentrytitle><manvolnum>3</manvolnum></citerefentry>,

<citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>,

<citerefentry><refentrytitle>fprintf</refentrytitle><manvolnum>3</manvolnum></citerefentry>,

<citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>

</para>

</refsect1>

</refentry>