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systemd/man/sd_journal_stream_fd.xml
Zbigniew Jędrzejewski-Szmek 5aded36978 man: add a mapping for external manpages
It is annoying when we have dead links on fd.o.

Add project='man-pages|die-net|archlinux' to <citerefentry>-ies.

In generated html, add external links to
http://man7.org/linux/man-pages/man, http://linux.die.net/man/,
https://www.archlinux.org/.

By default, pages in sections 2 and 4 go to man7, since Michael
Kerrisk is the autorative source on kernel related stuff.

The rest of links goes to linux.die.net, because they have the
manpages.

Except for the pacman stuff, since it seems to be only available from
archlinux.org.

Poor gummiboot gets no link, because gummitboot(8) ain't to be found
on the net. According to common wisdom, that would mean that it does
not exist. But I have seen Kay using it, so I know it does, and
deserves to be found. Can somebody be nice and put it up somewhere?
2014-07-07 18:36:55 -04:00

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<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
This file is part of systemd.
Copyright 2012 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->
<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 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 priority 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>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 a shared library, which can
be compiled and linked to with the
<constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
file.</para>
</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>#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 project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry project='man-pages'><refentrytitle>fprintf</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>