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<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 &lt;systemd/sd-journal.h&gt;</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>