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1 | <?xml version='1.0'?> <!--*-nxml-*--> |
2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" | |
12b42c76 | 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
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4 | |
5 | <!-- | |
572eb058 | 6 | SPDX-License-Identifier: LGPL-2.1+ |
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7 | --> |
8 | ||
7d6b2723 | 9 | <refentry id="sd_journal_seek_head" xmlns:xi="http://www.w3.org/2001/XInclude"> |
639a6a25 | 10 | |
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11 | <refentryinfo> |
12 | <title>sd_journal_seek_head</title> | |
13 | <productname>systemd</productname> | |
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14 | </refentryinfo> |
15 | ||
16 | <refmeta> | |
17 | <refentrytitle>sd_journal_seek_head</refentrytitle> | |
18 | <manvolnum>3</manvolnum> | |
19 | </refmeta> | |
20 | ||
21 | <refnamediv> | |
22 | <refname>sd_journal_seek_head</refname> | |
23 | <refname>sd_journal_seek_tail</refname> | |
24 | <refname>sd_journal_seek_monotonic_usec</refname> | |
25 | <refname>sd_journal_seek_realtime_usec</refname> | |
26 | <refname>sd_journal_seek_cursor</refname> | |
27 | <refpurpose>Seek to a position in the | |
28 | journal</refpurpose> | |
29 | </refnamediv> | |
30 | ||
31 | <refsynopsisdiv> | |
32 | <funcsynopsis> | |
33 | <funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo> | |
34 | ||
35 | <funcprototype> | |
36 | <funcdef>int <function>sd_journal_seek_head</function></funcdef> | |
37 | <paramdef>sd_journal *<parameter>j</parameter></paramdef> | |
38 | </funcprototype> | |
39 | ||
40 | <funcprototype> | |
41 | <funcdef>int <function>sd_journal_seek_tail</function></funcdef> | |
42 | <paramdef>sd_journal *<parameter>j</parameter></paramdef> | |
43 | </funcprototype> | |
44 | ||
45 | <funcprototype> | |
46 | <funcdef>int <function>sd_journal_seek_monotonic_usec</function></funcdef> | |
47 | <paramdef>sd_journal *<parameter>j</parameter></paramdef> | |
48 | <paramdef>sd_id128_t <parameter>boot_id</parameter></paramdef> | |
49 | <paramdef>uint64_t <parameter>usec</parameter></paramdef> | |
50 | </funcprototype> | |
51 | ||
52 | <funcprototype> | |
53 | <funcdef>int <function>sd_journal_seek_realtime_usec</function></funcdef> | |
54 | <paramdef>sd_journal *<parameter>j</parameter></paramdef> | |
55 | <paramdef>uint64_t <parameter>usec</parameter></paramdef> | |
56 | </funcprototype> | |
57 | ||
58 | <funcprototype> | |
59 | <funcdef>int <function>sd_journal_seek_cursor</function></funcdef> | |
60 | <paramdef>sd_journal *<parameter>j</parameter></paramdef> | |
61 | <paramdef>const char *<parameter>cursor</parameter></paramdef> | |
62 | </funcprototype> | |
63 | </funcsynopsis> | |
64 | </refsynopsisdiv> | |
65 | ||
66 | <refsect1> | |
67 | <title>Description</title> | |
68 | ||
69 | <para><function>sd_journal_seek_head()</function> seeks to the | |
70 | beginning of the journal, i.e. the oldest available entry.</para> | |
71 | ||
72 | <para>Similarly, <function>sd_journal_seek_tail()</function> may | |
73 | be used to seek to the end of the journal, i.e. the most recent | |
74 | available entry.</para> | |
75 | ||
76 | <para><function>sd_journal_seek_monotonic_usec()</function> seeks | |
77 | to the entry with the specified monotonic timestamp, i.e. | |
78 | <constant>CLOCK_MONOTONIC</constant>. Since monotonic time | |
79 | restarts on every reboot a boot ID needs to be specified as | |
80 | well.</para> | |
81 | ||
82 | <para><function>sd_journal_seek_realtime_usec()</function> seeks | |
83 | to the entry with the specified realtime (wallclock) timestamp, | |
84 | i.e. <constant>CLOCK_REALTIME</constant>. Note that the realtime | |
85 | clock is not necessarily monotonic. If a realtime timestamp is | |
86 | ambiguous, it is not defined which position is sought to.</para> | |
87 | ||
88 | <para><function>sd_journal_seek_cursor()</function> seeks to the | |
89 | entry located at the specified cursor string. For details on | |
90 | cursors, see | |
91 | <citerefentry><refentrytitle>sd_journal_get_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>. | |
92 | If no entry matching the specified cursor is found the call will | |
93 | seek to the next closest entry (in terms of time) instead. To | |
94 | verify whether the newly selected entry actually matches the | |
95 | cursor, use | |
96 | <citerefentry><refentrytitle>sd_journal_test_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para> | |
97 | ||
98 | <para>Note that these calls do not actually make any entry the new | |
99 | current entry, this needs to be done in a separate step with a | |
100 | subsequent | |
101 | <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
102 | invocation (or a similar call). Only then, entry data may be | |
103 | retrieved via | |
104 | <citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>. | |
105 | If no entry exists that matches exactly the specified seek | |
106 | address, the next closest is sought to. If | |
107 | <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
108 | is used, the closest following entry will be sought to, if | |
109 | <citerefentry><refentrytitle>sd_journal_previous</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
110 | is used the closest preceding entry is sought to.</para> | |
111 | </refsect1> | |
112 | ||
113 | <refsect1> | |
114 | <title>Return Value</title> | |
115 | ||
116 | <para>The functions return 0 on success or a negative errno-style | |
117 | error code.</para> | |
118 | </refsect1> | |
119 | ||
120 | <refsect1> | |
121 | <title>Notes</title> | |
122 | ||
64a7ef8b | 123 | <xi:include href="threads-aware.xml" xpointer="strict"/> |
a8d46a16 | 124 | |
7d6b2723 | 125 | <xi:include href="libsystemd-pkgconfig.xml" xpointer="pkgconfig-text"/> |
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126 | </refsect1> |
127 | ||
128 | <refsect1> | |
129 | <title>See Also</title> | |
130 | ||
131 | <para> | |
132 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
133 | <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
134 | <citerefentry><refentrytitle>sd_journal_open</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
135 | <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
136 | <citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
137 | <citerefentry><refentrytitle>sd_journal_get_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
138 | <citerefentry><refentrytitle>sd_journal_get_realtime_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
139 | </para> | |
140 | </refsect1> | |
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141 | |
142 | </refentry> |