+++ /dev/null
-<?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_print">
-
- <refentryinfo>
- <title>sd_journal_print</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_print</refentrytitle>
- <manvolnum>3</manvolnum>
- </refmeta>
-
- <refnamediv>
- <refname>sd_journal_print</refname>
- <refname>sd_journal_printv</refname>
- <refname>sd_journal_send</refname>
- <refname>sd_journal_sendv</refname>
- <refname>sd_journal_perror</refname>
- <refname>SD_JOURNAL_SUPPRESS_LOCATION</refname>
- <refpurpose>Submit log entries to the journal</refpurpose>
- </refnamediv>
-
- <refsynopsisdiv>
- <funcsynopsis>
- <funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo>
-
- <funcprototype>
- <funcdef>int <function>sd_journal_print</function></funcdef>
- <paramdef>int <parameter>priority</parameter></paramdef>
- <paramdef>const char *<parameter>format</parameter></paramdef>
- <paramdef>...</paramdef>
- </funcprototype>
-
- <funcprototype>
- <funcdef>int <function>sd_journal_printv</function></funcdef>
- <paramdef>int <parameter>priority</parameter></paramdef>
- <paramdef>const char *<parameter>format</parameter></paramdef>
- <paramdef>va_list <parameter>ap</parameter></paramdef>
- </funcprototype>
-
- <funcprototype>
- <funcdef>int <function>sd_journal_send</function></funcdef>
- <paramdef>const char *<parameter>format</parameter></paramdef>
- <paramdef>...</paramdef>
- </funcprototype>
-
- <funcprototype>
- <funcdef>int <function>sd_journal_sendv</function></funcdef>
- <paramdef>const struct iovec *<parameter>iov</parameter></paramdef>
- <paramdef>int <parameter>n</parameter></paramdef>
- </funcprototype>
-
- <funcprototype>
- <funcdef>int <function>sd_journal_perror</function></funcdef>
- <paramdef>const char *<parameter>message</parameter></paramdef>
- </funcprototype>
-
- </funcsynopsis>
- </refsynopsisdiv>
-
- <refsect1>
- <title>Description</title>
-
- <para><function>sd_journal_print()</function> may be used to
- submit simple, plain text log entries to the system journal. The
- first argument is a priority value. This is followed by a format
- string and its parameters, similar to
- <citerefentry project='man-pages'><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry>
- or
- <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
- The priority value 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. It is recommended to use this call to submit log
- messages in the application locale or system locale and in UTF-8
- format, but no such restrictions are enforced.</para>
-
- <para><function>sd_journal_printv()</function> is similar to
- <function>sd_journal_print()</function> but takes a variable
- argument list encapsulated in an object of type
- <varname>va_list</varname> (see
- <citerefentry project='man-pages'><refentrytitle>stdarg</refentrytitle><manvolnum>3</manvolnum></citerefentry>
- for more information) instead of the format string. It is
- otherwise equivalent in behavior.</para>
-
- <para><function>sd_journal_send()</function> may be used to submit
- structured log entries to the system journal. It takes a series of
- format strings, each immediately followed by their associated
- parameters, terminated by <constant>NULL</constant>. The strings
- passed should be of the format <literal>VARIABLE=value</literal>.
- The variable name must be in uppercase and consist only of
- characters, numbers and underscores, and may not begin with an
- underscore. (All assignments that do not follow this syntax will
- be ignored.) The value can be of any size and format. It is highly
- recommended to submit text strings formatted in the UTF-8
- character encoding only, and submit binary fields only when
- formatting in UTF-8 strings is not sensible. A number of well
- known fields are defined, see
- <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
- for details, but additional application defined fields may be
- used. A variable may be assigned more than one value per
- entry.</para>
-
- <para><function>sd_journal_sendv()</function> is similar to
- <function>sd_journal_send()</function> but takes an array of
- <varname>struct iovec</varname> (as defined in
- <filename>uio.h</filename>, see
- <citerefentry project='man-pages'><refentrytitle>readv</refentrytitle><manvolnum>3</manvolnum></citerefentry>
- for details) instead of the format string. Each structure should
- reference one field of the entry to submit. The second argument
- specifies the number of structures in the array.
- <function>sd_journal_sendv()</function> is particularly useful to
- submit binary objects to the journal where that is
- necessary.</para>
-
- <para><function>sd_journal_perror()</function> is a similar to
- <citerefentry project='die-net'><refentrytitle>perror</refentrytitle><manvolnum>3</manvolnum></citerefentry>
- and writes a message to the journal that consists of the passed
- string, suffixed with ": " and a human readable representation of
- the current error code stored in
- <citerefentry project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
- If the message string is passed as <constant>NULL</constant> or
- empty string, only the error string representation will be
- written, prefixed with nothing. An additional journal field ERRNO=
- is included in the entry containing the numeric error code
- formatted as decimal string. The log priority used is
- <constant>LOG_ERR</constant> (3).</para>
-
- <para>Note that <function>sd_journal_send()</function> is a
- wrapper around <function>sd_journal_sendv()</function> to make it
- easier to use when only text strings shall be submitted. Also, the
- following two calls are mostly equivalent:</para>
-
- <programlisting>sd_journal_print(LOG_INFO, "Hello World, this is PID %lu!", (unsigned long) getpid());
-
-sd_journal_send("MESSAGE=Hello World, this is PID %lu!", (unsigned long) getpid(),
- "PRIORITY=%i", LOG_INFO,
- NULL);</programlisting>
-
- <para>Note that these calls implicitly add fields for the source
- file, function name and code line where invoked. This is
- implemented with macros. If this is not desired, it can be turned
- off by defining SD_JOURNAL_SUPPRESS_LOCATION before including
- <filename>sd-journal.h</filename>.</para>
-
- <para><citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
- and <function>sd_journal_print()</function> may
- largely be used interchangeably
- functionality-wise. However, note that log messages
- logged via the former take a different path to the
- journal server than the later, and hence global
- chronological ordering between the two streams cannot
- be guaranteed. Using
- <function>sd_journal_print()</function> has the
- benefit of logging source code line, filenames, and
- functions as metadata along all entries, and
- guaranteeing chronological ordering with structured
- log entries that are generated via
- <function>sd_journal_send()</function>. Using
- <function>syslog()</function> has the benefit of being
- more portable.</para>
- </refsect1>
-
- <refsect1>
- <title>Return Value</title>
-
- <para>The four calls return 0 on success or a negative errno-style
- error code. The
- <citerefentry project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>
- variable itself is not altered.</para>
-
- <para>If
- <citerefentry><refentrytitle>systemd-journald</refentrytitle><manvolnum>8</manvolnum></citerefentry>
- is not running (the socket is not present), those functions do
- nothing, and also return 0.</para>
- </refsect1>
-
- <refsect1>
- <title>Async signal safety</title>
- <para><function>sd_journal_sendv()</function> is "async signal
- safe" in the meaning of
- <citerefentry project='man-pages'><refentrytitle>signal</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
- </para>
-
- <para><function>sd_journal_print</function>,
- <function>sd_journal_printv</function>,
- <function>sd_journal_send</function>, and
- <function>sd_journal_perror</function> are
- not async signal safe.</para>
- </refsect1>
-
- <refsect1>
- <title>Notes</title>
-
- <para>The <function>sd_journal_print()</function>,
- <function>sd_journal_printv()</function>,
- <function>sd_journal_send()</function> and
- <function>sd_journal_sendv()</function> interfaces are 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>See Also</title>
-
- <para>
- <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>sd_journal_stream_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
- <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
- <citerefentry project='die-net'><refentrytitle>perror</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
- <citerefentry project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
- <citerefentry project='man-pages'><refentrytitle>signal</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
- <citerefentry project='man-pages'><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>
- </para>
- </refsect1>
-
-</refentry>
~ianmdlvl / elogind.git / blobdiff