Cross Reference: /systemd/man/sd_journal_open.xml
sd_journal_open.xml revision 4a010f4e6e95964d7acaa33be768dbdb5e46d72a
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync<?xml version='1.0'?> <!--*-nxml-*-->
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync<!--
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync This file is part of systemd.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Copyright 2012 Lennart Poettering
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync systemd is free software; you can redistribute it and/or modify it
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync under the terms of the GNU Lesser General Public License as published by
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync the Free Software Foundation; either version 2.1 of the License, or
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync (at your option) any later version.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync systemd is distributed in the hope that it will be useful, but
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync WITHOUT ANY WARRANTY; without even the implied warranty of
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Lesser General Public License for more details.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync You should have received a copy of the GNU Lesser General Public License
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync along with systemd; If not, see <http://www.gnu.org/licenses/>.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync-->
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync<refentry id="sd_journal_open">
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync <refentryinfo>
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync <title>sd_journal_open</title>
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync <productname>systemd</productname>
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync <authorgroup>
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync <author>
<contrib>Developer</contrib>
<firstname>Lennart</firstname>
<surname>Poettering</surname>
<email>lennart@poettering.net</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>sd_journal_open</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_journal_open</refname>
<refname>sd_journal_open_directory</refname>
<refname>sd_journal_close</refname>
<refpurpose>Open the system journal for reading</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include &lt;systemd/sd-journal.h&gt;</funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>sd_journal_open</function></funcdef>
<paramdef>sd_journal** <parameter>ret</parameter></paramdef>
<paramdef>int <parameter>flags</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_journal_open_directory</function></funcdef>
<paramdef>sd_journal** <parameter>ret</parameter></paramdef>
<paramdef>const char* <parameter>path</parameter></paramdef>
<paramdef>int <parameter>flags</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_journal_close</function></funcdef>
<paramdef>sd_journal* <parameter>j</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_journal_open()</function> opens the
the log journal for reading. It will find all journal
files automatically and interleave them automatically
when reading. As first argument it takes a pointer to
a <literal>sd_journal</literal> pointer, which on
success will contain journal context afterwards. The
second argument is a flags field, which may consist of
the following flags ORed together:
<literal>SD_JOURNAL_LOCAL_ONLY</literal> makes sure
only journal files generated on the local machine will
be opened. <literal>SD_JOURNAL_RUNTIME_ONLY</literal>
makes sure only volatile journal files will be opened,
excluding those which are stored on persistant
storage. <literal>SD_JOURNAL_SYSTEM_ONLY</literal>
will ensure that only journal files of system services
and the kernel (in opposition to user session processes) will
be opened.</para>
<para><function>sd_journal_open_directory()</function>
is similar to <function>sd_journal_open()</function>
but takes an absolute directory path as argument. All
journal files in this directory will be opened and
interleaved automatically. This call also takes a
flags argument, but it must be passed as 0 as no flags
are currently understood for this call.</para>
<para><function>sd_journal_close()</function> will
close the journal context allocated with
<function>sd_journal_open()</function> or
<function>sd_journal_open_directory()</function> and
free its resources.</para>
<para>When opening the journal only journal files
accessible to the calling user will be opened. If
journal files are not accessible to the caller this
will be silently ignored.</para>
<para>See
<citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
for an example how to iterate through the journal
after opening it it with
<function>sd_journal_open()</function>.</para>
<para>A journal context object returned by
<function>sd_journal_open()</function> references a
specific journal entry as <emphasis>current</emphasis> entry,
similar to a file seek index in a classic file system
file, but without absolute positions. It may be
altered with
<citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
and
<citerefentry><refentrytitle>sd_journal_seek_head</refentrytitle><manvolnum>3</manvolnum></citerefentry>
and related calls. The current entry position may be
exported in <emphasis>cursor</emphasis> strings, as accessible
via
<citerefentry><refentrytitle>sd_journal_get_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>. Cursor
strings may be used to globally identify a specific
journal entry in a stable way and then later to seek
to it (or if the specific entry is not available
locally, to its closest entry in time)
<citerefentry><refentrytitle>sd_journal_seek_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>The <function>sd_journal_open()</function> and
<function>sd_journal_open_directory()</function> calls
return 0 on success or a negative errno-style error
code. <function>sd_journal_close()</function> returns
nothing.</para>
</refsect1>
<refsect1>
<title>Notes</title>
<para>The <function>sd_journal_open()</function>,
<function>sd_journal_open_directory()</function> and
<function>sd_journal_close()</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_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>