1 <?xml version='1.0'?> <!--*-nxml-*-->
2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
6 This file is part of systemd.
8 Copyright 2012 Lennart Poettering
10 systemd is free software; you can redistribute it and/or modify it
11 under the terms of the GNU Lesser General Public License as published by
12 the Free Software Foundation; either version 2.1 of the License, or
13 (at your option) any later version.
15 systemd is distributed in the hope that it will be useful, but
16 WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 Lesser General Public License for more details.
20 You should have received a copy of the GNU Lesser General Public License
21 along with systemd; If not, see <http://www.gnu.org/licenses/>.
24 <refentry id="sd_journal_seek_head">
27 <title>sd_journal_seek_head</title>
28 <productname>systemd</productname>
32 <contrib>Developer</contrib>
33 <firstname>Lennart</firstname>
34 <surname>Poettering</surname>
35 <email>lennart@poettering.net</email>
41 <refentrytitle>sd_journal_seek_head</refentrytitle>
42 <manvolnum>3</manvolnum>
46 <refname>sd_journal_seek_head</refname>
47 <refname>sd_journal_seek_tail</refname>
48 <refname>sd_journal_seek_monotonic_usec</refname>
49 <refname>sd_journal_seek_realtime_usec</refname>
50 <refname>sd_journal_seek_cursor</refname>
51 <refpurpose>Seek to a position in the
57 <funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo>
60 <funcdef>int <function>sd_journal_seek_head</function></funcdef>
61 <paramdef>sd_journal* <parameter>j</parameter></paramdef>
65 <funcdef>int <function>sd_journal_seek_tail</function></funcdef>
66 <paramdef>sd_journal* <parameter>j</parameter></paramdef>
70 <funcdef>int <function>sd_journal_seek_monotonic_usec</function></funcdef>
71 <paramdef>sd_journal* <parameter>j</parameter></paramdef>
72 <paramdef>sd_id128_t <parameter>boot_id</parameter></paramdef>
73 <paramdef>uint64_t <parameter>usec</parameter></paramdef>
77 <funcdef>int <function>sd_journal_seek_realtime_usec</function></funcdef>
78 <paramdef>sd_journal* <parameter>j</parameter></paramdef>
79 <paramdef>uint64_t <parameter>usec</parameter></paramdef>
83 <funcdef>int <function>sd_journal_seek_cursor</function></funcdef>
84 <paramdef>sd_journal* <parameter>j</parameter></paramdef>
85 <paramdef>const char * <parameter>cursor</parameter></paramdef>
91 <title>Description</title>
93 <para><function>sd_journal_seek_head()</function>
94 seeks to the beginning of the journal, i.e. the oldest
95 available entry.</para>
98 <function>sd_journal_seek_tail()</function> may be
99 used to seek to the end of the journal, i.e. the most
100 recent available entry.</para>
102 <para><function>sd_journal_seek_monotonic_usec()</function>
103 seeks to the entry with the specified monotonic
104 timestamp, i.e. CLOCK_MONOOTONIC. Since monotonic time
105 restarts on every reboot a boot ID needs to be
106 specified as well.</para>
108 <para><function>sd_journal_seek_realtime_usec()</function>
109 seeks to the entry with the specified realtime
110 (wallclock) timestamp, i.e. CLOCK_REALTIME. Note that
111 the realtime clock is not necessary monotonic. If a
112 realtime timestamp is ambiguous it is not defined
113 which position is sought to.</para>
115 <para><function>sd_journal_seek_cursor()</function>
116 seeks to the entry located at the specified cursor
117 string. For details on cursors see
118 <citerefentry><refentrytitle>sd_journal_get_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
120 <para>Note that these calls do not actually make any
121 entry the new current entry, this needs to be done in
122 a separate step with a subsequent
123 <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
124 invocation (or a similar call). Only then entry data
126 <citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>. If
127 no entry exists that matches exactly the specified
128 seek address the next closest is sought to. If
129 <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
130 is used the closest following entry will be sought to,
132 <citerefentry><refentrytitle>sd_journal_previous</refentrytitle><manvolnum>3</manvolnum></citerefentry>
133 is used the closest preceding entry is sought
138 <title>Return Value</title>
140 <para>The functions return 0 on success or a negative
141 errno-style error code.</para>
147 <para>The <function>sd_journal_seek_head()</function>,
148 <function>sd_journal_seek_tail()</function>,
149 <function>sd_journal_seek_monotonic_usec()</function>,
150 <function>sd_journal_seek_realtime_usec()</function>,
151 and <function>sd_journal_seek_cursor()</function>
152 interfaces are available as shared library, which can
153 be compiled and linked to with the
154 <literal>libsystemd-journal</literal>
155 <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
160 <title>See Also</title>
163 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
164 <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
165 <citerefentry><refentrytitle>sd_journal_open</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
166 <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
167 <citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
168 <citerefentry><refentrytitle>sd_journal_get_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
169 <citerefentry><refentrytitle>sd_journal_get_realtime_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>