mirror of
https://github.com/systemd/systemd-stable.git
synced 2024-10-29 21:55:25 +03:00
e9dd9f9547
Use proper grammar, word usage, adjective hyphenation, commas, capitalization, spelling, etc. To improve readability, some run-on sentences or sentence fragments were revised. [zj: remove the space from 'file name', 'host name', and 'time zone'.]
251 lines
13 KiB
XML
251 lines
13 KiB
XML
<?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><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
||
or
|
||
<citerefentry><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><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><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><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><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><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><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 meta data 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><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
||
variable itself is not altered.</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 shared library, which can be compiled
|
||
and linked to with the
|
||
<constant>libsystemd-journal</constant> <citerefentry><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><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>perror</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
|
||
</para>
|
||
</refsect1>
|
||
|
||
</refentry>
|