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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"> | |
4 | ||
5 | <!-- | |
6 | This file is part of systemd. | |
7 | ||
8 | Copyright 2012 Lennart Poettering | |
9 | ||
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. | |
14 | ||
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. | |
19 | ||
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/>. | |
22 | --> | |
23 | ||
24 | <refentry id="sd_journal_seek_head"> | |
25 | ||
26 | <refentryinfo> | |
27 | <title>sd_journal_seek_head</title> | |
28 | <productname>systemd</productname> | |
29 | ||
30 | <authorgroup> | |
31 | <author> | |
32 | <contrib>Developer</contrib> | |
33 | <firstname>Lennart</firstname> | |
34 | <surname>Poettering</surname> | |
35 | <email>lennart@poettering.net</email> | |
36 | </author> | |
37 | </authorgroup> | |
38 | </refentryinfo> | |
39 | ||
40 | <refmeta> | |
41 | <refentrytitle>sd_journal_seek_head</refentrytitle> | |
42 | <manvolnum>3</manvolnum> | |
43 | </refmeta> | |
44 | ||
45 | <refnamediv> | |
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 | |
52 | journal</refpurpose> | |
53 | </refnamediv> | |
54 | ||
55 | <refsynopsisdiv> | |
56 | <funcsynopsis> | |
57 | <funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo> | |
58 | ||
59 | <funcprototype> | |
60 | <funcdef>int <function>sd_journal_seek_head</function></funcdef> | |
61 | <paramdef>sd_journal* <parameter>j</parameter></paramdef> | |
62 | </funcprototype> | |
63 | ||
64 | <funcprototype> | |
65 | <funcdef>int <function>sd_journal_seek_tail</function></funcdef> | |
66 | <paramdef>sd_journal* <parameter>j</parameter></paramdef> | |
67 | </funcprototype> | |
68 | ||
69 | <funcprototype> | |
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> | |
74 | </funcprototype> | |
75 | ||
76 | <funcprototype> | |
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> | |
80 | </funcprototype> | |
81 | ||
82 | <funcprototype> | |
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> | |
86 | </funcprototype> | |
87 | </funcsynopsis> | |
88 | </refsynopsisdiv> | |
89 | ||
90 | <refsect1> | |
91 | <title>Description</title> | |
92 | ||
93 | <para><function>sd_journal_seek_head()</function> | |
94 | seeks to the beginning of the journal, i.e. the oldest | |
49f43d5f | 95 | available entry.</para> |
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96 | |
97 | <para>Similar, | |
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> | |
101 | ||
102 | <para><function>sd_journal_seek_monotonic_usec()</function> | |
103 | seeks to the entry with the specified monotonic | |
3ef51b2c | 104 | timestamp, i.e. CLOCK_MONOTONIC. Since monotonic time |
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105 | restarts on every reboot a boot ID needs to be |
106 | specified as well.</para> | |
107 | ||
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 | |
bb31a4ac | 111 | the realtime clock is not necessarily monotonic. If a |
639a6a25 | 112 | realtime timestamp is ambiguous it is not defined |
49f43d5f | 113 | which position is sought to.</para> |
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114 | |
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 | |
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118 | <citerefentry><refentrytitle>sd_journal_get_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>. If |
119 | no entry matching the specified cursor is found the | |
120 | call will seek to the next closest entry (in terms of | |
121 | time) instead. To verify whether the newly selected | |
122 | entry actually matches the cursor use | |
123 | <citerefentry><refentrytitle>sd_journal_test_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para> | |
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124 | |
125 | <para>Note that these calls do not actually make any | |
126 | entry the new current entry, this needs to be done in | |
127 | a separate step with a subsequent | |
128 | <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
129 | invocation (or a similar call). Only then entry data | |
130 | may be retrieved via | |
131 | <citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>. If | |
132 | no entry exists that matches exactly the specified | |
49f43d5f | 133 | seek address the next closest is sought to. If |
639a6a25 | 134 | <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry> |
49f43d5f | 135 | is used the closest following entry will be sought to, |
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136 | if |
137 | <citerefentry><refentrytitle>sd_journal_previous</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
49f43d5f | 138 | is used the closest preceding entry is sought |
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139 | to.</para> |
140 | </refsect1> | |
141 | ||
142 | <refsect1> | |
143 | <title>Return Value</title> | |
144 | ||
145 | <para>The functions return 0 on success or a negative | |
146 | errno-style error code.</para> | |
147 | </refsect1> | |
148 | ||
149 | <refsect1> | |
150 | <title>Notes</title> | |
151 | ||
152 | <para>The <function>sd_journal_seek_head()</function>, | |
153 | <function>sd_journal_seek_tail()</function>, | |
154 | <function>sd_journal_seek_monotonic_usec()</function>, | |
155 | <function>sd_journal_seek_realtime_usec()</function>, | |
156 | and <function>sd_journal_seek_cursor()</function> | |
157 | interfaces are available as shared library, which can | |
158 | be compiled and linked to with the | |
159 | <literal>libsystemd-journal</literal> | |
160 | <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
161 | file.</para> | |
162 | </refsect1> | |
163 | ||
164 | <refsect1> | |
165 | <title>See Also</title> | |
166 | ||
167 | <para> | |
168 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
169 | <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
170 | <citerefentry><refentrytitle>sd_journal_open</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
171 | <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
172 | <citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
173 | <citerefentry><refentrytitle>sd_journal_get_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
174 | <citerefentry><refentrytitle>sd_journal_get_realtime_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
175 | </para> | |
176 | </refsect1> | |
177 | ||
178 | </refentry> |