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<refentry id="sd_journal_seek_head">

<refentryinfo>

<title>sd_journal_seek_head</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_seek_head</refentrytitle>

<manvolnum>3</manvolnum>

</refmeta>

<refnamediv>

<refname>sd_journal_seek_head</refname>

<refname>sd_journal_seek_tail</refname>

<refname>sd_journal_seek_monotonic_usec</refname>

<refname>sd_journal_seek_realtime_usec</refname>

<refname>sd_journal_seek_cursor</refname>

<refpurpose>Seek to a position in the

journal</refpurpose>

</refnamediv>

<refsynopsisdiv>

<funcsynopsis>

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

<funcprototype>

<funcdef>int <function>sd_journal_seek_head</function></funcdef>

<paramdef>sd_journal* <parameter>j</parameter></paramdef>

</funcprototype>

<funcprototype>

<funcdef>int <function>sd_journal_seek_tail</function></funcdef>

<paramdef>sd_journal* <parameter>j</parameter></paramdef>

</funcprototype>

<funcprototype>

<funcdef>int <function>sd_journal_seek_monotonic_usec</function></funcdef>

<paramdef>sd_journal* <parameter>j</parameter></paramdef>

<paramdef>sd_id128_t <parameter>boot_id</parameter></paramdef>

<paramdef>uint64_t <parameter>usec</parameter></paramdef>

</funcprototype>

<funcprototype>

<funcdef>int <function>sd_journal_seek_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_seek_cursor</function></funcdef>

<paramdef>sd_journal* <parameter>j</parameter></paramdef>

<paramdef>const char * <parameter>cursor</parameter></paramdef>

</funcprototype>

</funcsynopsis>

</refsynopsisdiv>

<refsect1>

<title>Description</title>

<para><function>sd_journal_seek_head()</function>

seeks to the beginning of the journal, i.e. the oldest

available entry.</para>

<para>Similar,

<function>sd_journal_seek_tail()</function> may be

used to seek to the end of the journal, i.e. the most

recent available entry.</para>

<para><function>sd_journal_seek_monotonic_usec()</function>

seeks to the entry with the specified monotonic

timestamp,

i.e. <constant>CLOCK_MONOTONIC</constant>. Since

monotonic time restarts on every reboot a boot ID

needs to be specified as well.</para>

<para><function>sd_journal_seek_realtime_usec()</function>

seeks to the entry with the specified realtime

(wallclock) timestamp,

i.e. <constant>CLOCK_REALTIME</constant>. Note that

the realtime clock is not necessarily monotonic. If a

realtime timestamp is ambiguous it is not defined

which position is sought to.</para>

<para><function>sd_journal_seek_cursor()</function>

seeks to the entry located at the specified cursor

string. For details on cursors see

<citerefentry><refentrytitle>sd_journal_get_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>. If

no entry matching the specified cursor is found the

call will seek to the next closest entry (in terms of

time) instead. To verify whether the newly selected

entry actually matches the cursor use

<citerefentry><refentrytitle>sd_journal_test_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>

<para>Note that these calls do not actually make any

entry the new current entry, this needs to be done in

a separate step with a subsequent

<citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>

invocation (or a similar call). Only then entry data

may be retrieved via

<citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>. If

no entry exists that matches exactly the specified

seek address the next closest is sought to. If

<citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>

is used the closest following entry will be sought to,

if

<citerefentry><refentrytitle>sd_journal_previous</refentrytitle><manvolnum>3</manvolnum></citerefentry>

is used the closest preceding entry is sought

to.</para>

</refsect1>

<refsect1>

<title>Return Value</title>

<para>The functions return 0 on success or a negative

errno-style error code.</para>

</refsect1>

<refsect1>

<title>Notes</title>

<para>The <function>sd_journal_seek_head()</function>,

<function>sd_journal_seek_tail()</function>,

<function>sd_journal_seek_monotonic_usec()</function>,

<function>sd_journal_seek_realtime_usec()</function>,

and <function>sd_journal_seek_cursor()</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_journal_get_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>,

<citerefentry><refentrytitle>sd_journal_get_realtime_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>

</para>

</refsect1>

</refentry>