<?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_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 <systemd/sd-journal.h></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. CLOCK_MONOOTONIC. 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. CLOCK_REALTIME. Note that the realtime clock is not necessary 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>.</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 <literal>libsystemd-journal</literal> <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>