<?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_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, -ESTALE 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 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_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>