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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_open"> | |
25 | ||
26 | <refentryinfo> | |
27 | <title>sd_journal_open</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_open</refentrytitle> | |
42 | <manvolnum>3</manvolnum> | |
43 | </refmeta> | |
44 | ||
45 | <refnamediv> | |
46 | <refname>sd_journal_open</refname> | |
47 | <refname>sd_journal_open_directory</refname> | |
5302ebe1 | 48 | <refname>sd_journal_open_files</refname> |
b6741478 | 49 | <refname>sd_journal_open_container</refname> |
3bb55eee | 50 | <refname>sd_journal_close</refname> |
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51 | <refname>sd_journal</refname> |
52 | <refname>SD_JOURNAL_LOCAL_ONLY</refname> | |
53 | <refname>SD_JOURNAL_RUNTIME_ONLY</refname> | |
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54 | <refname>SD_JOURNAL_SYSTEM</refname> |
55 | <refname>SD_JOURNAL_CURRENT_USER</refname> | |
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56 | <refpurpose>Open the system journal for reading</refpurpose> |
57 | </refnamediv> | |
58 | ||
59 | <refsynopsisdiv> | |
60 | <funcsynopsis> | |
61 | <funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo> | |
62 | ||
63 | <funcprototype> | |
64 | <funcdef>int <function>sd_journal_open</function></funcdef> | |
65 | <paramdef>sd_journal** <parameter>ret</parameter></paramdef> | |
66 | <paramdef>int <parameter>flags</parameter></paramdef> | |
67 | </funcprototype> | |
68 | ||
69 | <funcprototype> | |
70 | <funcdef>int <function>sd_journal_open_directory</function></funcdef> | |
71 | <paramdef>sd_journal** <parameter>ret</parameter></paramdef> | |
72 | <paramdef>const char* <parameter>path</parameter></paramdef> | |
73 | <paramdef>int <parameter>flags</parameter></paramdef> | |
74 | </funcprototype> | |
75 | ||
5302ebe1 ZJS |
76 | <funcprototype> |
77 | <funcdef>int <function>sd_journal_open_files</function></funcdef> | |
78 | <paramdef>sd_journal** <parameter>ret</parameter></paramdef> | |
79 | <paramdef>const char** <parameter>paths</parameter></paramdef> | |
80 | <paramdef>int <parameter>flags</parameter></paramdef> | |
81 | </funcprototype> | |
82 | ||
b6741478 LP |
83 | <funcprototype> |
84 | <funcdef>int <function>sd_journal_open_container</function></funcdef> | |
85 | <paramdef>sd_journal** <parameter>ret</parameter></paramdef> | |
86 | <paramdef>const char* <parameter>machine</parameter></paramdef> | |
87 | <paramdef>int <parameter>flags</parameter></paramdef> | |
88 | </funcprototype> | |
89 | ||
3bb55eee | 90 | <funcprototype> |
486aad23 | 91 | <funcdef>void <function>sd_journal_close</function></funcdef> |
3bb55eee LP |
92 | <paramdef>sd_journal* <parameter>j</parameter></paramdef> |
93 | </funcprototype> | |
94 | </funcsynopsis> | |
95 | </refsynopsisdiv> | |
96 | ||
97 | <refsect1> | |
98 | <title>Description</title> | |
99 | ||
bb31a4ac | 100 | <para><function>sd_journal_open()</function> opens |
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101 | the log journal for reading. It will find all journal |
102 | files automatically and interleave them automatically | |
103 | when reading. As first argument it takes a pointer to | |
74d00578 | 104 | a <varname>sd_journal</varname> pointer, which on |
aed63d67 | 105 | success will contain a journal context object. The |
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106 | second argument is a flags field, which may consist of |
107 | the following flags ORed together: | |
74d00578 | 108 | <constant>SD_JOURNAL_LOCAL_ONLY</constant> makes sure |
3bb55eee | 109 | only journal files generated on the local machine will |
74d00578 | 110 | be opened. <constant>SD_JOURNAL_RUNTIME_ONLY</constant> |
3bb55eee | 111 | makes sure only volatile journal files will be opened, |
49f43d5f | 112 | excluding those which are stored on persistent |
74d00578 | 113 | storage. <constant>SD_JOURNAL_SYSTEM</constant> |
a688baa8 ZJS |
114 | will cause journal files of system services and the |
115 | kernel (in opposition to user session processes) to | |
74d00578 | 116 | be opened. <constant>SD_JOURNAL_CURRENT_USER</constant> |
a688baa8 | 117 | will cause journal files of the current user to be |
74d00578 ZJS |
118 | opened. If neither <constant>SD_JOURNAL_SYSTEM</constant> |
119 | nor <constant>SD_JOURNAL_CURRENT_USER</constant> are | |
a688baa8 | 120 | specified, all journal file types will be opened.</para> |
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121 | |
122 | <para><function>sd_journal_open_directory()</function> | |
123 | is similar to <function>sd_journal_open()</function> | |
124 | but takes an absolute directory path as argument. All | |
125 | journal files in this directory will be opened and | |
126 | interleaved automatically. This call also takes a | |
127 | flags argument, but it must be passed as 0 as no flags | |
128 | are currently understood for this call.</para> | |
129 | ||
5302ebe1 ZJS |
130 | <para><function>sd_journal_open_files()</function> |
131 | is similar to <function>sd_journal_open()</function> | |
74d00578 | 132 | but takes a <constant>NULL</constant>-terminated list |
5302ebe1 ZJS |
133 | of file paths to open. All files will be opened and |
134 | interleaved automatically. This call also takes a | |
135 | flags argument, but it must be passed as 0 as no flags | |
7699b6eb | 136 | are currently understood for this call. Please note |
aed63d67 | 137 | that in the case of a live journal, this function is only |
7699b6eb ZJS |
138 | useful for debugging, because individual journal files |
139 | can be rotated at any moment, and the opening of | |
aed63d67 | 140 | specific files is inherently racy.</para> |
5302ebe1 | 141 | |
b6741478 LP |
142 | <para><function>sd_journal_open_container()</function> |
143 | is similar to <function>sd_journal_open()</function> | |
144 | but opens the journal files of a running | |
145 | OS container. The specified machine name refers to a | |
146 | container that is registered with | |
147 | <citerefentry><refentrytitle>systemd-machined</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para> | |
148 | ||
a65f06bb ZJS |
149 | <para><varname>sd_journal</varname> objects cannot be |
150 | used in the child after a fork. Functions which take a | |
151 | journal object as an argument | |
152 | (<function>sd_journal_next()</function> and others) | |
153 | will return <constant>-ECHILD</constant> after a fork. | |
154 | </para> | |
155 | ||
3bb55eee LP |
156 | <para><function>sd_journal_close()</function> will |
157 | close the journal context allocated with | |
158 | <function>sd_journal_open()</function> or | |
159 | <function>sd_journal_open_directory()</function> and | |
160 | free its resources.</para> | |
161 | ||
162 | <para>When opening the journal only journal files | |
163 | accessible to the calling user will be opened. If | |
79640424 | 164 | journal files are not accessible to the caller, this |
3bb55eee | 165 | will be silently ignored.</para> |
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166 | |
167 | <para>See | |
168 | <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
aed63d67 | 169 | for an example of how to iterate through the journal |
bb31a4ac | 170 | after opening it with |
67c3cf4f | 171 | <function>sd_journal_open()</function>.</para> |
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172 | |
173 | <para>A journal context object returned by | |
174 | <function>sd_journal_open()</function> references a | |
175 | specific journal entry as <emphasis>current</emphasis> entry, | |
176 | similar to a file seek index in a classic file system | |
177 | file, but without absolute positions. It may be | |
178 | altered with | |
179 | <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
180 | and | |
181 | <citerefentry><refentrytitle>sd_journal_seek_head</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
182 | and related calls. The current entry position may be | |
183 | exported in <emphasis>cursor</emphasis> strings, as accessible | |
184 | via | |
185 | <citerefentry><refentrytitle>sd_journal_get_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>. Cursor | |
186 | strings may be used to globally identify a specific | |
187 | journal entry in a stable way and then later to seek | |
188 | to it (or if the specific entry is not available | |
189 | locally, to its closest entry in time) | |
190 | <citerefentry><refentrytitle>sd_journal_seek_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para> | |
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191 | |
192 | <para>Notification of journal changes is available via | |
193 | <function>sd_journal_get_fd()</function> and related | |
194 | calls.</para> | |
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195 | </refsect1> |
196 | ||
197 | <refsect1> | |
198 | <title>Return Value</title> | |
199 | ||
5e9dfd2e ZJS |
200 | <para>The <function>sd_journal_open()</function>, |
201 | <function>sd_journal_open_directory()</function>, and | |
202 | <function>sd_journal_open_files()</function> calls | |
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203 | return 0 on success or a negative errno-style error |
204 | code. <function>sd_journal_close()</function> returns | |
205 | nothing.</para> | |
206 | </refsect1> | |
207 | ||
208 | <refsect1> | |
209 | <title>Notes</title> | |
210 | ||
211 | <para>The <function>sd_journal_open()</function>, | |
212 | <function>sd_journal_open_directory()</function> and | |
213 | <function>sd_journal_close()</function> interfaces are | |
aed63d67 | 214 | available as a shared library, which can be compiled and |
3bb55eee | 215 | linked to with the |
1e158d27 | 216 | <constant>libsystemd-journal</constant> <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> |
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217 | file.</para> |
218 | </refsect1> | |
219 | ||
a688baa8 ZJS |
220 | <refsect1> |
221 | <title>History</title> | |
222 | ||
223 | <para><function>sd_journal_open()</function>, | |
224 | <function>sd_journal_close()</function>, | |
74d00578 ZJS |
225 | <constant>SD_JOURNAL_LOCAL_ONLY</constant>, |
226 | <constant>SD_JOURNAL_RUNTIME_ONLY</constant>, | |
227 | <constant>SD_JOURNAL_SYSTEM_ONLY</constant> were added | |
a688baa8 ZJS |
228 | in systemd-38.</para> |
229 | ||
230 | <para><function>sd_journal_open_directory()</function> | |
231 | was added in systemd-187.</para> | |
232 | ||
74d00578 ZJS |
233 | <para><constant>SD_JOURNAL_SYSTEM</constant>, |
234 | <constant>SD_JOURNAL_CURRENT_USER</constant>, | |
5302ebe1 ZJS |
235 | and <function>sd_journal_open_files()</function> |
236 | were added in systemd-205. | |
74d00578 | 237 | <constant>SD_JOURNAL_SYSTEM_ONLY</constant> |
a688baa8 ZJS |
238 | was deprecated.</para> |
239 | </refsect1> | |
240 | ||
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241 | <refsect1> |
242 | <title>See Also</title> | |
243 | ||
244 | <para> | |
245 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
246 | <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
247 | <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
b6741478 LP |
248 | <citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
249 | <citerefentry><refentrytitle>systemd-machined</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
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250 | </para> |
251 | </refsect1> | |
252 | ||
253 | </refentry> |