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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 | <!-- | |
6 | This file is part of systemd. | |
7 | ||
8 | Copyright 2010 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="systemd-journald.service"> | |
25 | ||
798d3a52 ZJS |
26 | <refentryinfo> |
27 | <title>systemd-journald.service</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>systemd-journald.service</refentrytitle> | |
42 | <manvolnum>8</manvolnum> | |
43 | </refmeta> | |
44 | ||
45 | <refnamediv> | |
46 | <refname>systemd-journald.service</refname> | |
47 | <refname>systemd-journald.socket</refname> | |
48 | <refname>systemd-journald-dev-log.socket</refname> | |
49 | <refname>systemd-journald</refname> | |
50 | <refpurpose>Journal service</refpurpose> | |
51 | </refnamediv> | |
52 | ||
53 | <refsynopsisdiv> | |
54 | <para><filename>systemd-journald.service</filename></para> | |
55 | <para><filename>systemd-journald.socket</filename></para> | |
56 | <para><filename>systemd-journald-dev-log.socket</filename></para> | |
12b42c76 | 57 | <para><filename>/usr/lib/systemd/systemd-journald</filename></para> |
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58 | </refsynopsisdiv> |
59 | ||
60 | <refsect1> | |
61 | <title>Description</title> | |
62 | ||
63 | <para><filename>systemd-journald</filename> is a system service | |
64 | that collects and stores logging data. It creates and maintains | |
65 | structured, indexed journals based on logging information that is | |
66 | received from a variety of sources:</para> | |
67 | ||
68 | <itemizedlist> | |
69 | <listitem><para>Kernel log messages, via kmsg</para></listitem> | |
70 | ||
71 | <listitem><para>Simple system log messages, via the libc | |
72 | <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
73 | call</para></listitem> | |
74 | ||
75 | <listitem><para>Structured system log messages via the native | |
76 | Journal API, see | |
77 | <citerefentry><refentrytitle>sd_journal_print</refentrytitle><manvolnum>4</manvolnum></citerefentry></para></listitem> | |
78 | ||
79 | <listitem><para>Standard output and standard error of system | |
80 | services</para></listitem> | |
81 | ||
82 | <listitem><para>Audit records, via the audit | |
83 | subsystem</para></listitem> | |
84 | </itemizedlist> | |
85 | ||
86 | <para>The daemon will implicitly collect numerous metadata fields | |
87 | for each log messages in a secure and unfakeable way. See | |
88 | <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
89 | for more information about the collected metadata. | |
90 | </para> | |
91 | ||
92 | <para>Log data collected by the journal is primarily text-based | |
93 | but can also include binary data where necessary. All objects | |
94 | stored in the journal can be up to 2^64-1 bytes in size.</para> | |
95 | ||
96 | <para>By default, the journal stores log data in | |
97 | <filename>/run/log/journal/</filename>. Since | |
98 | <filename>/run/</filename> is volatile, log data is lost at | |
99 | reboot. To make the data persistent, it is sufficient to create | |
100 | <filename>/var/log/journal/</filename> where | |
101 | <filename>systemd-journald</filename> will then store the | |
102 | data.</para> | |
103 | ||
104 | <para><filename>systemd-journald</filename> will forward all | |
105 | received log messages to the | |
106 | <constant>AF_UNIX</constant>/<constant>SOCK_DGRAM</constant> | |
107 | socket <filename>/run/systemd/journal/syslog</filename>, if it | |
108 | exists, which may be used by Unix syslog daemons to process the | |
109 | data further.</para> | |
110 | ||
111 | <para>See | |
112 | <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
113 | for information about the configuration of this service.</para> | |
114 | </refsect1> | |
115 | ||
116 | <refsect1> | |
117 | <title>Signals</title> | |
118 | ||
119 | <variablelist> | |
120 | <varlistentry> | |
121 | <term>SIGUSR1</term> | |
122 | ||
123 | <listitem><para>Request that journal data from | |
124 | <filename>/run/</filename> is flushed to | |
125 | <filename>/var/</filename> in order to make it persistent (if | |
126 | this is enabled). This must be used after | |
127 | <filename>/var/</filename> is mounted, as otherwise log data | |
128 | from <filename>/run</filename> is never flushed to | |
129 | <filename>/var</filename> regardless of the | |
130 | configuration.</para></listitem> | |
131 | </varlistentry> | |
132 | ||
133 | <varlistentry> | |
134 | <term>SIGUSR2</term> | |
135 | ||
136 | <listitem><para>Request immediate rotation of the journal | |
137 | files.</para></listitem> | |
138 | </varlistentry> | |
139 | </variablelist> | |
140 | </refsect1> | |
141 | ||
142 | <refsect1> | |
143 | <title>Kernel Command Line</title> | |
144 | ||
145 | <para>A few configuration parameters from | |
146 | <filename>journald.conf</filename> may be overridden on the kernel | |
147 | command line:</para> | |
148 | ||
149 | <variablelist class='kernel-commandline-options'> | |
150 | <varlistentry> | |
151 | <term><varname>systemd.journald.forward_to_syslog=</varname></term> | |
152 | <term><varname>systemd.journald.forward_to_kmsg=</varname></term> | |
153 | <term><varname>systemd.journald.forward_to_console=</varname></term> | |
154 | <term><varname>systemd.journald.forward_to_wall=</varname></term> | |
155 | ||
156 | <listitem><para>Enables/disables forwarding of collected log | |
157 | messages to syslog, the kernel log buffer, the system console | |
158 | or wall. | |
159 | </para> | |
160 | ||
161 | <para>See | |
162 | <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
163 | for information about these settings.</para> | |
164 | </listitem> | |
165 | ||
166 | </varlistentry> | |
167 | </variablelist> | |
168 | </refsect1> | |
169 | ||
170 | <refsect1> | |
171 | <title>Access Control</title> | |
172 | ||
173 | <para>Journal files are, by default, owned and readable by the | |
174 | <literal>systemd-journal</literal> system group but are not | |
175 | writable. Adding a user to this group thus enables her/him to read | |
176 | the journal files.</para> | |
177 | ||
178 | <para>By default, each logged in user will get her/his own set of | |
179 | journal files in <filename>/var/log/journal/</filename>. These | |
180 | files will not be owned by the user, however, in order to avoid | |
181 | that the user can write to them directly. Instead, file system | |
182 | ACLs are used to ensure the user gets read access only.</para> | |
183 | ||
184 | <para>Additional users and groups may be granted access to journal | |
185 | files via file system access control lists (ACL). Distributions | |
186 | and administrators may choose to grant read access to all members | |
187 | of the <literal>wheel</literal> and <literal>adm</literal> system | |
188 | groups with a command such as the following:</para> | |
189 | ||
190 | <programlisting># setfacl -Rnm g:wheel:rx,d:g:wheel:rx,g:adm:rx,d:g:adm:rx /var/log/journal/</programlisting> | |
191 | ||
192 | <para>Note that this command will update the ACLs both for | |
193 | existing journal files and for future journal files created in the | |
194 | <filename>/var/log/journal/</filename> directory.</para> | |
195 | </refsect1> | |
196 | ||
197 | <refsect1> | |
198 | <title>Files</title> | |
199 | ||
200 | <variablelist> | |
201 | <varlistentry> | |
12b42c76 | 202 | <term><filename>/etc/systemd/journald.conf</filename></term> |
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203 | |
204 | <listitem><para>Configure | |
205 | <command>systemd-journald</command> | |
dd2b607b | 206 | behavior. See |
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207 | <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>. |
208 | </para></listitem> | |
209 | </varlistentry> | |
210 | ||
211 | <varlistentry> | |
212 | <term><filename>/run/log/journal/<replaceable>machine-id</replaceable>/*.journal</filename></term> | |
213 | <term><filename>/run/log/journal/<replaceable>machine-id</replaceable>/*.journal~</filename></term> | |
214 | <term><filename>/var/log/journal/<replaceable>machine-id</replaceable>/*.journal</filename></term> | |
215 | <term><filename>/var/log/journal/<replaceable>machine-id</replaceable>/*.journal~</filename></term> | |
216 | ||
217 | <listitem><para><command>systemd-journald</command> writes | |
218 | entries to files in | |
219 | <filename>/run/log/journal/<replaceable>machine-id</replaceable>/</filename> | |
220 | or | |
221 | <filename>/var/log/journal/<replaceable>machine-id</replaceable>/</filename> | |
222 | with the <literal>.journal</literal> suffix. If the daemon is | |
223 | stopped uncleanly, or if the files are found to be corrupted, | |
224 | they are renamed using the <literal>.journal~</literal> | |
225 | suffix, and <command>systemd-journald</command> starts writing | |
226 | to a new file. <filename>/run</filename> is used when | |
227 | <filename>/var/log/journal</filename> is not available, or | |
228 | when <option>Storage=volatile</option> is set in the | |
229 | <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
230 | configuration file. </para></listitem> | |
231 | </varlistentry> | |
232 | </variablelist> | |
233 | </refsect1> | |
234 | ||
235 | <refsect1> | |
236 | <title>See Also</title> | |
237 | <para> | |
238 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
239 | <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
240 | <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
241 | <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>, | |
242 | <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
243 | <citerefentry><refentrytitle>systemd-coredump</refentrytitle><manvolnum>8</manvolnum></citerefentry>, | |
3ba3a79d | 244 | <citerefentry project='die-net'><refentrytitle>setfacl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, |
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245 | <citerefentry><refentrytitle>sd_journal_print</refentrytitle><manvolnum>4</manvolnum></citerefentry>, |
246 | <command>pydoc systemd.journal</command>. | |
247 | </para> | |
248 | </refsect1> | |
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249 | |
250 | </refentry> |