<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
+ 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
+ call, from standard input and standard error 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
+ 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
+ <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
+ <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
+ forward all received log messages to the <constant>AF_UNIX</constant>
+ <constant>SOCK_DGRAM</constant> 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
is flushed to
<filename>/var/</filename> in order to
make it persistent (if this is
- enabled). This may be used after
+ enabled). This must 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>
+ as otherwise log data from
+ <filename>/run</filename> is never
+ flushed to <filename>/var</filename>
+ regardless of the
+ configuration.</para></listitem>
</varlistentry>
<varlistentry>
<refsect1>
<title>Access Control</title>
- <para>Journal files are by default owned and readable
+ <para>Journal files are, by default, owned and readable
by the <literal>systemd-journal</literal> system group
- (but not writable). Adding a user to this group thus
+ but are not writable. Adding a user to this group thus
enables her/him to read the journal files.</para>
<para>By default, each logged in user will get her/his
own set of journal files in
<filename>/var/log/journal/</filename>. These files
- will not be owned by the user however, in order to
+ will not be owned by the user, however, in order to
avoid that the user can write to them
directly. Instead, file system ACLs are used to ensure
the user gets read access only.</para>
directory.</para>
</refsect1>
+ <refsect1>
+ <title>Files</title>
+
+ <variablelist>
+ <varlistentry>
+ <term><filename>/etc/systemd/journald.conf</filename></term>
+
+ <listitem><para>Configure
+ <command>systemd-journald</command>
+ behaviour. See
+ <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><filename>/run/log/journal/<replaceable>machine-id</replaceable>/*.journal</filename></term>
+ <term><filename>/run/log/journal/<replaceable>machine-id</replaceable>/*.journal~</filename></term>
+ <term><filename>/var/log/journal/<replaceable>machine-id</replaceable>/*.journal</filename></term>
+ <term><filename>/var/log/journal/<replaceable>machine-id</replaceable>/*.journal~</filename></term>
+
+ <listitem><para><command>systemd-journald</command>
+ writes entries to files in
+ <filename>/run/log/journal/<replaceable>machine-id</replaceable>/</filename>
+ or
+ <filename>/var/log/journal/<replaceable>machine-id</replaceable>/</filename>
+ with the <literal>.journal</literal>
+ suffix. If the daemon is stopped
+ uncleanly, or if the files are found
+ to be corrupted, they are renamed
+ using the <literal>.journal~</literal>
+ suffix, and
+ <command>systemd-journald</command>
+ starts writing to a new
+ file. <filename>/run</filename> is
+ used when
+ <filename>/var/log/journal</filename>
+ is not available, or when
+ <option>Storage=volatile</option> is
+ set in the
+ <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ configuration file.
+ </para></listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+
<refsect1>
<title>See Also</title>
<para>
<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>,
- <citerefentry><refentrytitle>setfacl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+ <citerefentry><refentrytitle>setfacl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <command>pydoc systemd.journal</command>.
</para>
</refsect1>
~ianmdlvl / elogind.git / blobdiff