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12b42c7667
This did not really work out as we had hoped. Trying to do this upstream introduced several problems that probably makes it better suited as a downstream patch after all. At any rate, it is not releaseable in the current state, so we at least need to revert this before the release. * by adjusting the path to binaries, but not do the same thing to the search path we end up with inconsistent man-pages. Adjusting the search path too would be quite messy, and it is not at all obvious that this is worth the effort, but at any rate it would have to be done before we could ship this. * this means that distributed man-pages does not make sense as they depend on config options, and for better or worse we are still distributing man pages, so that is something that definitely needs sorting out before we could ship with this patch. * we have long held that split-usr is only minimally supported in order to boot, and something we hope will eventually go away. So before we start adding even more magic/effort in order to make this work nicely, we should probably question if it makes sense at all.
261 lines
11 KiB
XML
261 lines
11 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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This file is part of systemd.
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Copyright 2012 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="sd_journal_print">
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<refentryinfo>
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<title>sd_journal_print</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>sd_journal_print</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>sd_journal_print</refname>
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<refname>sd_journal_printv</refname>
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<refname>sd_journal_send</refname>
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<refname>sd_journal_sendv</refname>
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<refname>sd_journal_perror</refname>
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<refname>SD_JOURNAL_SUPPRESS_LOCATION</refname>
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<refpurpose>Submit log entries to the journal</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo>
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<funcprototype>
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<funcdef>int <function>sd_journal_print</function></funcdef>
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<paramdef>int <parameter>priority</parameter></paramdef>
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<paramdef>const char *<parameter>format</parameter></paramdef>
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<paramdef>...</paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_journal_printv</function></funcdef>
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<paramdef>int <parameter>priority</parameter></paramdef>
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<paramdef>const char *<parameter>format</parameter></paramdef>
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<paramdef>va_list <parameter>ap</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_journal_send</function></funcdef>
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<paramdef>const char *<parameter>format</parameter></paramdef>
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<paramdef>...</paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_journal_sendv</function></funcdef>
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<paramdef>const struct iovec *<parameter>iov</parameter></paramdef>
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<paramdef>int <parameter>n</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_journal_perror</function></funcdef>
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<paramdef>const char *<parameter>message</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><function>sd_journal_print()</function> may be used to
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submit simple, plain text log entries to the system journal. The
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first argument is a priority value. This is followed by a format
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string and its parameters, similar to
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<citerefentry project='man-pages'><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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or
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<citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
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The priority value is one of
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<constant>LOG_EMERG</constant>,
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<constant>LOG_ALERT</constant>,
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<constant>LOG_CRIT</constant>,
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<constant>LOG_ERR</constant>,
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<constant>LOG_WARNING</constant>,
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<constant>LOG_NOTICE</constant>,
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<constant>LOG_INFO</constant>,
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<constant>LOG_DEBUG</constant>, as defined in
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<filename>syslog.h</filename>, see
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<citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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for details. It is recommended to use this call to submit log
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messages in the application locale or system locale and in UTF-8
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format, but no such restrictions are enforced.</para>
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<para><function>sd_journal_printv()</function> is similar to
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<function>sd_journal_print()</function> but takes a variable
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argument list encapsulated in an object of type
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<varname>va_list</varname> (see
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<citerefentry project='man-pages'><refentrytitle>stdarg</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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for more information) instead of the format string. It is
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otherwise equivalent in behavior.</para>
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<para><function>sd_journal_send()</function> may be used to submit
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structured log entries to the system journal. It takes a series of
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format strings, each immediately followed by their associated
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parameters, terminated by <constant>NULL</constant>. The strings
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passed should be of the format <literal>VARIABLE=value</literal>.
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The variable name must be in uppercase and consist only of
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characters, numbers and underscores, and may not begin with an
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underscore. (All assignments that do not follow this syntax will
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be ignored.) The value can be of any size and format. It is highly
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recommended to submit text strings formatted in the UTF-8
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character encoding only, and submit binary fields only when
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formatting in UTF-8 strings is not sensible. A number of well
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known fields are defined, see
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<citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
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for details, but additional application defined fields may be
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used. A variable may be assigned more than one value per
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entry.</para>
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<para><function>sd_journal_sendv()</function> is similar to
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<function>sd_journal_send()</function> but takes an array of
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<varname>struct iovec</varname> (as defined in
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<filename>uio.h</filename>, see
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<citerefentry project='man-pages'><refentrytitle>readv</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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for details) instead of the format string. Each structure should
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reference one field of the entry to submit. The second argument
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specifies the number of structures in the array.
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<function>sd_journal_sendv()</function> is particularly useful to
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submit binary objects to the journal where that is
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necessary.</para>
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<para><function>sd_journal_perror()</function> is a similar to
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<citerefentry project='die-net'><refentrytitle>perror</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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and writes a message to the journal that consists of the passed
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string, suffixed with ": " and a human readable representation of
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the current error code stored in
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<citerefentry project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
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If the message string is passed as <constant>NULL</constant> or
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empty string, only the error string representation will be
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written, prefixed with nothing. An additional journal field ERRNO=
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is included in the entry containing the numeric error code
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formatted as decimal string. The log priority used is
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<constant>LOG_ERR</constant> (3).</para>
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<para>Note that <function>sd_journal_send()</function> is a
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wrapper around <function>sd_journal_sendv()</function> to make it
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easier to use when only text strings shall be submitted. Also, the
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following two calls are mostly equivalent:</para>
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<programlisting>sd_journal_print(LOG_INFO, "Hello World, this is PID %lu!", (unsigned long) getpid());
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sd_journal_send("MESSAGE=Hello World, this is PID %lu!", (unsigned long) getpid(),
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"PRIORITY=%i", LOG_INFO,
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NULL);</programlisting>
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<para>Note that these calls implicitly add fields for the source
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file, function name and code line where invoked. This is
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implemented with macros. If this is not desired, it can be turned
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off by defining SD_JOURNAL_SUPPRESS_LOCATION before including
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<filename>sd-journal.h</filename>.</para>
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<para><citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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and <function>sd_journal_print()</function> may
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largely be used interchangeably
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functionality-wise. However, note that log messages
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logged via the former take a different path to the
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journal server than the later, and hence global
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chronological ordering between the two streams cannot
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be guaranteed. Using
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<function>sd_journal_print()</function> has the
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benefit of logging source code line, filenames, and
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functions as metadata along all entries, and
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guaranteeing chronological ordering with structured
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log entries that are generated via
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<function>sd_journal_send()</function>. Using
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<function>syslog()</function> has the benefit of being
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more portable.</para>
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</refsect1>
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<refsect1>
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<title>Return Value</title>
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<para>The four calls return 0 on success or a negative errno-style
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error code. The
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<citerefentry project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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variable itself is not altered.</para>
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<para>If
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<citerefentry><refentrytitle>systemd-journald</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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is not running (the socket is not present), those functions do
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nothing, and also return 0.</para>
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</refsect1>
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<refsect1>
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<title>Async signal safety</title>
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<para><function>sd_journal_sendv()</function> is "async signal
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safe" in the meaning of
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<citerefentry project='man-pages'><refentrytitle>signal</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
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</para>
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<para><function>sd_journal_print</function>,
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<function>sd_journal_printv</function>,
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<function>sd_journal_send</function>, and
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<function>sd_journal_perror</function> are
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not async signal safe.</para>
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</refsect1>
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<refsect1>
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<title>Notes</title>
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<para>The <function>sd_journal_print()</function>,
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<function>sd_journal_printv()</function>,
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<function>sd_journal_send()</function> and
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<function>sd_journal_sendv()</function> interfaces are available
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as a shared library, which can be compiled and linked to with the
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<constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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file.</para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_journal_stream_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry project='die-net'><refentrytitle>perror</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
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<citerefentry project='man-pages'><refentrytitle>signal</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
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<citerefentry project='man-pages'><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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