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Diffstat (limited to 'src/libsystemd/sd_journal_stream_fd.xml')
| -rw-r--r-- | src/libsystemd/sd_journal_stream_fd.xml | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/src/libsystemd/sd_journal_stream_fd.xml b/src/libsystemd/sd_journal_stream_fd.xml new file mode 100644 index 0000000000..db88eba1bc --- /dev/null +++ b/src/libsystemd/sd_journal_stream_fd.xml @@ -0,0 +1,167 @@ +<?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 <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> + + </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>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>Function <function>sd_journal_stream_fd()</function> is thread-safe and may be called + from multiple threads. All calls will return the same file descriptor, although temporarily + multiple file descriptors may be open.</para> + + <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 <syslog.h> +#include <stdio.h> +#include <string.h> +#include <unistd.h> +#include <systemd/sd-journal.h> +#include <systemd/sd-daemon.h> + +int main(int argc, char *argv[]) { + int fd; + FILE *log; + fd = sd_journal_stream_fd("test", LOG_INFO, 1); + if (fd < 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> |