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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" [
<!ENTITY % entities SYSTEM "custom-entities.ent" >
%entities;
]>
<!--
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_get_realtime_usec">
<refentryinfo>
<title>sd_journal_get_realtime_usec</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_get_realtime_usec</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_journal_get_realtime_usec</refname>
<refname>sd_journal_get_monotonic_usec</refname>
<refpurpose>Read timestamps from the current journal entry</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>sd_journal_get_realtime_usec</function></funcdef>
<paramdef>sd_journal *<parameter>j</parameter></paramdef>
<paramdef>uint64_t *<parameter>usec</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_journal_get_monotonic_usec</function></funcdef>
<paramdef>sd_journal *<parameter>j</parameter></paramdef>
<paramdef>uint64_t *<parameter>usec</parameter></paramdef>
<paramdef>sd_id128_t *<parameter>boot_id</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_journal_get_realtime_usec()</function> gets the
realtime (wallclock) timestamp of the current journal entry. It
takes two arguments: the journal context object and a pointer to a
64-bit unsigned integer to store the timestamp in. The timestamp
is in microseconds since the epoch, i.e.
<constant>CLOCK_REALTIME</constant>.</para>
<para><function>sd_journal_get_monotonic_usec()</function> gets
the monotonic timestamp of the current journal entry. It takes
three arguments: the journal context object, a pointer to a 64-bit
unsigned integer to store the timestamp in, as well as a 128-bit
ID buffer to store the boot ID of the monotonic timestamp. The
timestamp is in microseconds since boot-up of the specific boot,
i.e. <constant>CLOCK_MONOTONIC</constant>. Since the monotonic
clock begins new with every reboot, it only defines a well-defined
point in time when used together with an identifier identifying
the boot. See
<citerefentry><refentrytitle>sd_id128_get_boot</refentrytitle><manvolnum>3</manvolnum></citerefentry>
for more information. If the boot ID parameter is passed
<constant>NULL</constant>, the function will fail if the monotonic
timestamp of the current entry is not of the current system
boot.</para>
<para>Note that these functions will not work before
<citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
(or related call) has been called at least
once, in order to position the read pointer at a valid entry.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para><function>sd_journal_get_realtime_usec()</function> and
<function>sd_journal_get_monotonic_usec()</function> returns 0 on
success or a negative errno-style error code. If the boot ID
parameter was passed <constant>NULL</constant> and the monotonic
timestamp of the current journal entry is not of the current
system boot, <constant>-ESTALE</constant> is returned by
<function>sd_journal_get_monotonic_usec()</function>.</para>
</refsect1>
<refsect1>
<title>Notes</title>
<para>The <function>sd_journal_get_realtime_usec()</function> and
<function>sd_journal_get_monotonic_usec()</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_open</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_id128_get_boot</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>clock_gettime</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_journal_get_cutoff_realtime_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
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