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120 lines
5.1 KiB
XML
120 lines
5.1 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
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<refentry id="sd_journal_get_realtime_usec"
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xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>sd_journal_get_realtime_usec</title>
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<productname>systemd</productname>
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</refentryinfo>
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<refmeta>
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<refentrytitle>sd_journal_get_realtime_usec</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_get_realtime_usec</refname>
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<refname>sd_journal_get_monotonic_usec</refname>
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<refpurpose>Read timestamps from the current journal entry</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_get_realtime_usec</function></funcdef>
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<paramdef>sd_journal *<parameter>j</parameter></paramdef>
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<paramdef>uint64_t *<parameter>usec</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_journal_get_monotonic_usec</function></funcdef>
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<paramdef>sd_journal *<parameter>j</parameter></paramdef>
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<paramdef>uint64_t *<parameter>usec</parameter></paramdef>
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<paramdef>sd_id128_t *<parameter>boot_id</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_get_realtime_usec()</function> gets the
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realtime (wallclock) timestamp of the current journal entry. It
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takes two arguments: the journal context object and a pointer to a
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64-bit unsigned integer to store the timestamp in. The timestamp
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is in microseconds since the epoch, i.e.
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<constant>CLOCK_REALTIME</constant>.</para>
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<para><function>sd_journal_get_monotonic_usec()</function> gets
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the monotonic timestamp of the current journal entry. It takes
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three arguments: the journal context object, a pointer to a 64-bit
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unsigned integer to store the timestamp in, as well as a 128-bit
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ID buffer to store the boot ID of the monotonic timestamp. The
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timestamp is in microseconds since boot-up of the specific boot,
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i.e. <constant>CLOCK_MONOTONIC</constant>. Since the monotonic
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clock begins new with every reboot, it only defines a well-defined
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point in time when used together with an identifier identifying
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the boot. See
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<citerefentry><refentrytitle>sd_id128_get_boot</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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for more information. If the boot ID parameter is passed
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<constant>NULL</constant>, the function will fail if the monotonic
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timestamp of the current entry is not of the current system
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boot.</para>
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<para>Note that these functions will not work before
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<citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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(or related call) has been called at least
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once, in order to position the read pointer at a valid entry.</para>
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</refsect1>
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<refsect1>
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<title>Return Value</title>
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<para><function>sd_journal_get_realtime_usec()</function> and
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<function>sd_journal_get_monotonic_usec()</function> returns 0 on
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success or a negative errno-style error code. If the boot ID
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parameter was passed <constant>NULL</constant> and the monotonic
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timestamp of the current journal entry is not of the current
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system boot, <constant>-ESTALE</constant> is returned by
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<function>sd_journal_get_monotonic_usec()</function>.</para>
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</refsect1>
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<refsect1>
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<title>Notes</title>
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<xi:include href="threads-aware.xml" xpointer="strict"/>
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<xi:include href="libsystemd-pkgconfig.xml" xpointer="pkgconfig-text"/>
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</refsect1>
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<refsect1>
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<title>History</title>
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<para><function>sd_journal_get_realtime_usec()</function> and
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<function>sd_journal_get_monotonic_usec()</function> were added in version 187.</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_open</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_journal_get_seqnum</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_id128_get_boot</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>clock_gettime</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_journal_get_cutoff_realtime_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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