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
|
<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
This file is part of systemd.
Copyright 2010 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->
<refentry id="systemd-journald.service">
<refentryinfo>
<title>systemd-journald.service</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>Developer</contrib>
<firstname>Lennart</firstname>
<surname>Poettering</surname>
<email>lennart@poettering.net</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>systemd-journald.service</refentrytitle>
<manvolnum>8</manvolnum>
</refmeta>
<refnamediv>
<refname>systemd-journald.service</refname>
<refname>systemd-journald.socket</refname>
<refname>systemd-journald</refname>
<refpurpose>Journal service</refpurpose>
</refnamediv>
<refsynopsisdiv>
<para><filename>systemd-journald.service</filename></para>
<para><filename>systemd-journald.socket</filename></para>
<para><filename>/usr/lib/systemd/systemd-journald</filename></para>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><filename>systemd-journald</filename> is a
system service that collects and stores logging
data. It creates and maintains structured, indexed
journals based on logging information that is received
from the kernel, from user processes via the libc
<citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
call, from STDOUT/STDERR of system services or via its
native API. It will implicitly collect numerous meta
data fields for each log messages in a secure and
unfakeable way. See
<citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
for more information about the collected meta data.
</para>
<para>Log data collected by the journal is primarily
text based but can also include binary data where
necessary. All objects stored in the journal can be up
to 2^64-1 bytes in size.</para>
<para>By default the journal stores log data in
<filename>/run/log/journal/</filename>. Since
<filename>/run/</filename> is volatile log data is
lost at reboot. To make the data persistent it
is sufficient to create
<filename>/var/log/journal/</filename> where
<filename>systemd-journald</filename> will then store
the data.</para>
<para><filename>systemd-journald</filename> will
forward all received log messages to the AF_UNIX
SOCK_DGRAM socket
<filename>/run/systemd/journal/syslog</filename> (if it exists) which
may be used by UNIX syslog daemons to process the data
further.</para>
<para>See
<citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for information about the configuration of this
service.</para>
</refsect1>
<refsect1>
<title>Signals</title>
<variablelist>
<varlistentry>
<term>SIGUSR1</term>
<listitem><para>Request that journal
data from <filename>/run/</filename>
is flushed to
<filename>/var/</filename> in order to
make it persistent (if this is
enabled). This may be used after
<filename>/var/</filename> is mounted,
but is generally not required since
the first journal write when
<filename>/var/</filename> becomes
writable triggers the flushing
anyway.</para></listitem>
</varlistentry>
<varlistentry>
<term>SIGUSR2</term>
<listitem><para>Request immediate
rotation of the journal
files.</para></listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Kernel Command Line</title>
<para>A few configuration parameters from
<filename>journald.conf</filename> may be overridden on
the kernel command line:</para>
<variablelist class='kernel-commandline-options'>
<varlistentry>
<term><varname>systemd.journald.forward_to_syslog=</varname></term>
<term><varname>systemd.journald.forward_to_kmsg=</varname></term>
<term><varname>systemd.journald.forward_to_console=</varname></term>
<listitem><para>Enables/disables
forwarding of collected log messages
to syslog, the kernel log buffer or
the system console.
</para>
<para>See
<citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for information about these settings.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
|
