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3bb55eee | 1 | <?xml version='1.0'?> <!--*-nxml-*--> |
3a54a157 | 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
eea10b26 | 3 | "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd"> |
db9ecf05 | 4 | <!-- SPDX-License-Identifier: LGPL-2.1-or-later --> |
3bb55eee | 5 | |
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6 | <refentry id="sd_journal_open" |
7 | xmlns:xi="http://www.w3.org/2001/XInclude"> | |
3bb55eee | 8 | |
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9 | <refentryinfo> |
10 | <title>sd_journal_open</title> | |
11 | <productname>systemd</productname> | |
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12 | </refentryinfo> |
13 | ||
14 | <refmeta> | |
15 | <refentrytitle>sd_journal_open</refentrytitle> | |
16 | <manvolnum>3</manvolnum> | |
17 | </refmeta> | |
18 | ||
19 | <refnamediv> | |
20 | <refname>sd_journal_open</refname> | |
21 | <refname>sd_journal_open_directory</refname> | |
2aab2fab | 22 | <refname>sd_journal_open_directory_fd</refname> |
798d3a52 | 23 | <refname>sd_journal_open_files</refname> |
2aab2fab | 24 | <refname>sd_journal_open_files_fd</refname> |
21dc5e82 | 25 | <refname>sd_journal_open_namespace</refname> |
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26 | <refname>sd_journal_close</refname> |
27 | <refname>sd_journal</refname> | |
28 | <refname>SD_JOURNAL_LOCAL_ONLY</refname> | |
29 | <refname>SD_JOURNAL_RUNTIME_ONLY</refname> | |
30 | <refname>SD_JOURNAL_SYSTEM</refname> | |
31 | <refname>SD_JOURNAL_CURRENT_USER</refname> | |
2aab2fab | 32 | <refname>SD_JOURNAL_OS_ROOT</refname> |
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33 | <refname>SD_JOURNAL_ALL_NAMESPACES</refname> |
34 | <refname>SD_JOURNAL_INCLUDE_DEFAULT_NAMESPACE</refname> | |
4a45a2e0 | 35 | <refname>SD_JOURNAL_TAKE_DIRECTORY_FD</refname> |
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36 | <refpurpose>Open the system journal for reading</refpurpose> |
37 | </refnamediv> | |
38 | ||
39 | <refsynopsisdiv> | |
40 | <funcsynopsis> | |
41 | <funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo> | |
42 | ||
43 | <funcprototype> | |
44 | <funcdef>int <function>sd_journal_open</function></funcdef> | |
45 | <paramdef>sd_journal **<parameter>ret</parameter></paramdef> | |
46 | <paramdef>int <parameter>flags</parameter></paramdef> | |
47 | </funcprototype> | |
48 | ||
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49 | <funcprototype> |
50 | <funcdef>int <function>sd_journal_open_namespace</function></funcdef> | |
51 | <paramdef>sd_journal **<parameter>ret</parameter></paramdef> | |
52 | <paramdef>const char *<parameter>namespace</parameter></paramdef> | |
53 | <paramdef>int <parameter>flags</parameter></paramdef> | |
54 | </funcprototype> | |
55 | ||
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56 | <funcprototype> |
57 | <funcdef>int <function>sd_journal_open_directory</function></funcdef> | |
58 | <paramdef>sd_journal **<parameter>ret</parameter></paramdef> | |
59 | <paramdef>const char *<parameter>path</parameter></paramdef> | |
60 | <paramdef>int <parameter>flags</parameter></paramdef> | |
61 | </funcprototype> | |
62 | ||
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63 | <funcprototype> |
64 | <funcdef>int <function>sd_journal_open_directory_fd</function></funcdef> | |
65 | <paramdef>sd_journal **<parameter>ret</parameter></paramdef> | |
66 | <paramdef>int <parameter>fd</parameter></paramdef> | |
67 | <paramdef>int <parameter>flags</parameter></paramdef> | |
68 | </funcprototype> | |
69 | ||
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70 | <funcprototype> |
71 | <funcdef>int <function>sd_journal_open_files</function></funcdef> | |
72 | <paramdef>sd_journal **<parameter>ret</parameter></paramdef> | |
73 | <paramdef>const char **<parameter>paths</parameter></paramdef> | |
74 | <paramdef>int <parameter>flags</parameter></paramdef> | |
75 | </funcprototype> | |
76 | ||
77 | <funcprototype> | |
2aab2fab | 78 | <funcdef>int <function>sd_journal_open_files_fd</function></funcdef> |
798d3a52 | 79 | <paramdef>sd_journal **<parameter>ret</parameter></paramdef> |
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80 | <paramdef>int <parameter>fds[]</parameter></paramdef> |
81 | <paramdef>unsigned <parameter>n_fds</parameter></paramdef> | |
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82 | <paramdef>int <parameter>flags</parameter></paramdef> |
83 | </funcprototype> | |
84 | ||
85 | <funcprototype> | |
86 | <funcdef>void <function>sd_journal_close</function></funcdef> | |
87 | <paramdef>sd_journal *<parameter>j</parameter></paramdef> | |
88 | </funcprototype> | |
89 | </funcsynopsis> | |
90 | </refsynopsisdiv> | |
91 | ||
92 | <refsect1> | |
93 | <title>Description</title> | |
94 | ||
95 | <para><function>sd_journal_open()</function> opens the log journal | |
96 | for reading. It will find all journal files automatically and | |
97 | interleave them automatically when reading. As first argument it | |
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98 | takes a pointer to a <varname>sd_journal</varname> pointer, which, |
99 | on success, will contain a journal context object. The second | |
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100 | argument is a flags field, which may consist of the following |
101 | flags ORed together: <constant>SD_JOURNAL_LOCAL_ONLY</constant> | |
102 | makes sure only journal files generated on the local machine will | |
103 | be opened. <constant>SD_JOURNAL_RUNTIME_ONLY</constant> makes sure | |
104 | only volatile journal files will be opened, excluding those which | |
105 | are stored on persistent storage. | |
106 | <constant>SD_JOURNAL_SYSTEM</constant> will cause journal files of | |
107 | system services and the kernel (in opposition to user session | |
108 | processes) to be opened. | |
109 | <constant>SD_JOURNAL_CURRENT_USER</constant> will cause journal | |
110 | files of the current user to be opened. If neither | |
111 | <constant>SD_JOURNAL_SYSTEM</constant> nor | |
112 | <constant>SD_JOURNAL_CURRENT_USER</constant> are specified, all | |
113 | journal file types will be opened.</para> | |
114 | ||
241c8f67 LP |
115 | <para><function>sd_journal_open_namespace()</function> is similar to |
116 | <function>sd_journal_open()</function> but takes an additional <parameter>namespace</parameter> parameter | |
117 | that specifies which journal namespace to operate on. If specified as <constant>NULL</constant> the call | |
118 | is identical to <function>sd_journal_open()</function>. If non-<constant>NULL</constant> only data from | |
119 | the namespace identified by the specified parameter is accessed. This call understands two additional | |
120 | flags: if <constant>SD_JOURNAL_ALL_NAMESPACES</constant> is specified the | |
121 | <parameter>namespace</parameter> parameter is ignored and all defined namespaces are accessed | |
122 | simultaneously; if <constant>SD_JOURNAL_INCLUDE_DEFAULT_NAMESPACE</constant> the specified namespace and | |
123 | the default namespace are accessed but no others (this flag has no effect when | |
124 | <parameter>namespace</parameter> is passed as <constant>NULL</constant>). For details about journal | |
125 | namespaces see | |
126 | <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para> | |
127 | ||
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128 | <para><function>sd_journal_open_directory()</function> is similar to <function>sd_journal_open()</function> but |
129 | takes an absolute directory path as argument. All journal files in this directory will be opened and interleaved | |
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130 | automatically. This call also takes a flags argument. The flags parameters accepted by this call are |
131 | <constant>SD_JOURNAL_OS_ROOT</constant>, <constant>SD_JOURNAL_SYSTEM</constant>, and | |
132 | <constant>SD_JOURNAL_CURRENT_USER</constant>. If <constant>SD_JOURNAL_OS_ROOT</constant> is specified, journal | |
133 | files are searched for below the usual <filename>/var/log/journal</filename> and | |
134 | <filename>/run/log/journal</filename> relative to the specified path, instead of directly beneath it. | |
135 | The other two flags limit which files are opened, the same as for <function>sd_journal_open()</function>. | |
136 | </para> | |
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137 | |
138 | <para><function>sd_journal_open_directory_fd()</function> is similar to | |
139 | <function>sd_journal_open_directory()</function>, but takes a file descriptor referencing a directory in the file | |
627cdcc7 | 140 | system instead of an absolute file system path. In addition to the flags accepted by |
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141 | <function>sd_journal_open_directory()</function>, this function also accepts |
142 | <constant>SD_JOURNAL_TAKE_DIRECTORY_FD</constant>. If <constant>SD_JOURNAL_TAKE_DIRECTORY_FD</constant> is | |
143 | specified, the function will take the ownership of the specified file descriptor on success, and it will be | |
144 | closed by <function>sd_journal_close()</function>, hence the caller of the function must not close the file | |
145 | descriptor. When the flag is not specified, <function>sd_journal_close()</function> will not close the file | |
146 | descriptor, so the caller should close it after <function>sd_journal_close()</function>.</para> | |
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147 | |
148 | <para><function>sd_journal_open_files()</function> is similar to <function>sd_journal_open()</function> but takes a | |
149 | <constant>NULL</constant>-terminated list of file paths to open. All files will be opened and interleaved | |
150 | automatically. This call also takes a flags argument, but it must be passed as 0 as no flags are currently | |
151 | understood for this call. Please note that in the case of a live journal, this function is only useful for | |
152 | debugging, because individual journal files can be rotated at any moment, and the opening of specific files is | |
153 | inherently racy.</para> | |
154 | ||
155 | <para><function>sd_journal_open_files_fd()</function> is similar to <function>sd_journal_open_files()</function> | |
156 | but takes an array of open file descriptors that must reference journal files, instead of an array of file system | |
157 | paths. Pass the array of file descriptors as second argument, and the number of array entries in the third. The | |
158 | flags parameter must be passed as 0.</para> | |
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159 | |
160 | <para><varname>sd_journal</varname> objects cannot be used in the | |
161 | child after a fork. Functions which take a journal object as an | |
162 | argument (<function>sd_journal_next()</function> and others) will | |
163 | return <constant>-ECHILD</constant> after a fork. | |
164 | </para> | |
165 | ||
166 | <para><function>sd_journal_close()</function> will close the | |
167 | journal context allocated with | |
168 | <function>sd_journal_open()</function> or | |
169 | <function>sd_journal_open_directory()</function> and free its | |
170 | resources.</para> | |
171 | ||
172 | <para>When opening the journal only journal files accessible to | |
173 | the calling user will be opened. If journal files are not | |
174 | accessible to the caller, this will be silently ignored.</para> | |
175 | ||
176 | <para>See | |
177 | <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
178 | for an example of how to iterate through the journal after opening | |
179 | it with <function>sd_journal_open()</function>.</para> | |
180 | ||
181 | <para>A journal context object returned by | |
182 | <function>sd_journal_open()</function> references a specific | |
183 | journal entry as <emphasis>current</emphasis> entry, similar to a | |
184 | file seek index in a classic file system file, but without | |
185 | absolute positions. It may be altered with | |
186 | <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
187 | and | |
188 | <citerefentry><refentrytitle>sd_journal_seek_head</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
189 | and related calls. The current entry position may be exported in | |
190 | <emphasis>cursor</emphasis> strings, as accessible via | |
191 | <citerefentry><refentrytitle>sd_journal_get_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>. | |
192 | Cursor strings may be used to globally identify a specific journal | |
193 | entry in a stable way and then later to seek to it (or if the | |
194 | specific entry is not available locally, to its closest entry in | |
195 | time) | |
196 | <citerefentry><refentrytitle>sd_journal_seek_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para> | |
197 | ||
198 | <para>Notification of journal changes is available via | |
199 | <function>sd_journal_get_fd()</function> and related calls.</para> | |
200 | </refsect1> | |
201 | ||
202 | <refsect1> | |
203 | <title>Return Value</title> | |
204 | ||
205 | <para>The <function>sd_journal_open()</function>, | |
206 | <function>sd_journal_open_directory()</function>, and | |
207 | <function>sd_journal_open_files()</function> calls return 0 on | |
208 | success or a negative errno-style error code. | |
209 | <function>sd_journal_close()</function> returns nothing.</para> | |
210 | </refsect1> | |
211 | ||
212 | <refsect1> | |
213 | <title>Notes</title> | |
214 | ||
64a7ef8b | 215 | <xi:include href="threads-aware.xml" xpointer="strict"/> |
a8d46a16 | 216 | |
64a7ef8b | 217 | <xi:include href="libsystemd-pkgconfig.xml" xpointer="pkgconfig-text"/> |
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218 | </refsect1> |
219 | ||
69106f47 AK |
220 | <refsect1> |
221 | <title>History</title> | |
00f95506 AK |
222 | <para><function>sd_journal_open()</function>, |
223 | <function>sd_journal_open_directory()</function>, and | |
224 | <function>sd_journal_close()</function> were added in version 187.</para> | |
69106f47 | 225 | <para><function>sd_journal_open_files()</function> was added in version 205.</para> |
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226 | <para><function>sd_journal_open_directory_fd()</function> and |
227 | <function>sd_journal_open_files_fd()</function> were added in version 230.</para> | |
69106f47 AK |
228 | <para><function>sd_journal_open_namespace()</function> was added in version 245.</para> |
229 | </refsect1> | |
230 | ||
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231 | <refsect1> |
232 | <title>See Also</title> | |
233 | ||
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234 | <para><simplelist type="inline"> |
235 | <member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member> | |
236 | <member><citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> | |
237 | <member><citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member> | |
238 | <member><citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> | |
239 | <member><citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> | |
240 | </simplelist></para> | |
798d3a52 | 241 | </refsect1> |
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242 | |
243 | </refentry> |