"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
+ SPDX-License-Identifier: LGPL-2.1+
+
This file is part of systemd.
Copyright 2010 Lennart Poettering
<command>echo "hello" >&2</command> instead, which is mostly equivalent and avoids this pitfall.</para>
<para>This setting defaults to the value set with
- <option>DefaultStandardOutput=</option> in
+ <varname>DefaultStandardOutput=</varname> in
<citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
which defaults to <option>journal</option>. Note that setting
this parameter might result in additional dependencies to be
<literal>stderr</literal>.</para>
<para>This setting defaults to the value set with
- <option>DefaultStandardError=</option> in
+ <varname>DefaultStandardError=</varname> in
<citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
which defaults to <option>inherit</option>. Note that setting
this parameter might result in additional dependencies to be
that the screen and scrollback buffer is cleared. Defaults to
<literal>no</literal>.</para></listitem>
</varlistentry>
+
<varlistentry>
<term><varname>SyslogIdentifier=</varname></term>
- <listitem><para>Sets the process name to prefix log lines sent
- to the logging system or the kernel log buffer with. If not
- set, defaults to the process name of the executed process.
- This option is only useful when
- <varname>StandardOutput=</varname> or
- <varname>StandardError=</varname> are set to
- <option>syslog</option>, <option>journal</option> or
- <option>kmsg</option> (or to the same settings in combination
- with <option>+console</option>).</para></listitem>
+ <listitem><para>Sets the process name ("<command>syslog</command> tag") to prefix log lines sent to the logging
+ system or the kernel log buffer with. If not set, defaults to the process name of the executed process. This
+ option is only useful when <varname>StandardOutput=</varname> or <varname>StandardError=</varname> are set to
+ <option>journal</option>, <option>syslog</option> or <option>kmsg</option> (or to the same settings in
+ combination with <option>+console</option>) and only applies to log messages written to stdout or
+ stderr.</para></listitem>
</varlistentry>
+
<varlistentry>
<term><varname>SyslogFacility=</varname></term>
- <listitem><para>Sets the syslog facility to use when logging
- to syslog. One of <option>kern</option>,
- <option>user</option>, <option>mail</option>,
- <option>daemon</option>, <option>auth</option>,
- <option>syslog</option>, <option>lpr</option>,
- <option>news</option>, <option>uucp</option>,
- <option>cron</option>, <option>authpriv</option>,
- <option>ftp</option>, <option>local0</option>,
- <option>local1</option>, <option>local2</option>,
- <option>local3</option>, <option>local4</option>,
- <option>local5</option>, <option>local6</option> or
- <option>local7</option>. See
+ <listitem><para>Sets the <command>syslog</command> facility identifier to use when logging. One of
+ <option>kern</option>, <option>user</option>, <option>mail</option>, <option>daemon</option>,
+ <option>auth</option>, <option>syslog</option>, <option>lpr</option>, <option>news</option>,
+ <option>uucp</option>, <option>cron</option>, <option>authpriv</option>, <option>ftp</option>,
+ <option>local0</option>, <option>local1</option>, <option>local2</option>, <option>local3</option>,
+ <option>local4</option>, <option>local5</option>, <option>local6</option> or <option>local7</option>. See
<citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
- for details. This option is only useful when
- <varname>StandardOutput=</varname> or
- <varname>StandardError=</varname> are set to
- <option>syslog</option>. Defaults to
- <option>daemon</option>.</para></listitem>
+ for details. This option is only useful when <varname>StandardOutput=</varname> or
+ <varname>StandardError=</varname> are set to <option>journal</option>, <option>syslog</option> or
+ <option>kmsg</option> (or to the same settings in combination with <option>+console</option>), and only applies
+ to log messages written to stdout or stderr. Defaults to <option>daemon</option>.</para></listitem>
</varlistentry>
+
<varlistentry>
<term><varname>SyslogLevel=</varname></term>
- <listitem><para>The default syslog level to use when logging to
- syslog or the kernel log buffer. One of
- <option>emerg</option>,
- <option>alert</option>,
- <option>crit</option>,
- <option>err</option>,
- <option>warning</option>,
- <option>notice</option>,
- <option>info</option>,
- <option>debug</option>. See
- <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
- for details. This option is only useful when
- <varname>StandardOutput=</varname> or
- <varname>StandardError=</varname> are set to
- <option>syslog</option> or <option>kmsg</option>. Note that
- individual lines output by the daemon might be prefixed with a
- different log level which can be used to override the default
- log level specified here. The interpretation of these prefixes
- may be disabled with <varname>SyslogLevelPrefix=</varname>,
- see below. For details, see
- <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
+ <listitem><para>The default <command>syslog</command> log level to use when logging to the logging system or
+ the kernel log buffer. One of <option>emerg</option>, <option>alert</option>, <option>crit</option>,
+ <option>err</option>, <option>warning</option>, <option>notice</option>, <option>info</option>,
+ <option>debug</option>. See <citerefentry
+ project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> for
+ details. This option is only useful when <varname>StandardOutput=</varname> or
+ <varname>StandardError=</varname> are set to <option>journal</option>, <option>syslog</option> or
+ <option>kmsg</option> (or to the same settings in combination with <option>+console</option>), and only applies
+ to log messages written to stdout or stderr. Note that individual lines output by executed processes may be
+ prefixed with a different log level which can be used to override the default log level specified here. The
+ interpretation of these prefixes may be disabled with <varname>SyslogLevelPrefix=</varname>, see below. For
+ details, see <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
- Defaults to
- <option>info</option>.</para></listitem>
+ Defaults to <option>info</option>.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>SyslogLevelPrefix=</varname></term>
- <listitem><para>Takes a boolean argument. If true and
- <varname>StandardOutput=</varname> or
- <varname>StandardError=</varname> are set to
- <option>syslog</option>, <option>kmsg</option> or
- <option>journal</option>, log lines written by the executed
- process that are prefixed with a log level will be passed on
- to syslog with this log level set but the prefix removed. If
- set to false, the interpretation of these prefixes is disabled
- and the logged lines are passed on as-is. For details about
- this prefixing see
- <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
- Defaults to true.</para></listitem>
+ <listitem><para>Takes a boolean argument. If true and <varname>StandardOutput=</varname> or
+ <varname>StandardError=</varname> are set to <option>journal</option>, <option>syslog</option> or
+ <option>kmsg</option> (or to the same settings in combination with <option>+console</option>), log lines
+ written by the executed process that are prefixed with a log level will be processed with this log level set
+ but the prefix removed. If set to false, the interpretation of these prefixes is disabled and the logged lines
+ are passed on as-is. This only applies to log messages written to stdout or stderr. For details
+ about this prefixing see
+ <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>. Defaults to
+ true.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>LogLevelMax=</varname></term>
+ <listitem><para>Configures filtering by log level of log messages generated by this unit. Takes a
+ <command>syslog</command> log level, one of <option>emerg</option> (lowest log level, only highest priority
+ messages), <option>alert</option>, <option>crit</option>, <option>err</option>, <option>warning</option>,
+ <option>notice</option>, <option>info</option>, <option>debug</option> (highest log level, also lowest priority
+ messages). See <citerefentry
+ project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> for
+ details. By default no filtering is applied (i.e. the default maximum log level is <option>debug</option>). Use
+ this option to configure the logging system to drop log messages of a specific service above the specified
+ level. For example, set <varname>LogLevelMax=</varname><option>info</option> in order to turn off debug logging
+ of a particularly chatty unit. Note that the the configured level is applied to any log messages written by any
+ of the processes belonging to this unit, sent via any supported logging protocol. The filtering is applied
+ early in the logging pipeline, before any kind of further processing is done. Moreover, messages which pass
+ through this filter successfully might still be dropped by filters applied at a later stage in the logging
+ subsystem. For example, <varname>MaxLevelStore=</varname> configured in
+ <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> might
+ prohibit messages of higher log levels to be stored on disk, even though the per-unit
+ <varname>LogLevelMax=</varname> permitted it to be processed.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>LogExtraFields=</varname></term>
+ <listitem><para>Configures additional log metadata fields to include in all log records generated by processes
+ associated with this unit. This setting takes one or more journal field assignments in the format
+ <literal>FIELD=VALUE</literal> separated by whitespace. See
+ <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry> for
+ details on the journal field concept. Even though the underlying journal implementation permits binary field
+ values, this setting accepts only valid UTF-8 values. To include space characters in a journal field value,
+ enclose the assignment in double quotes ("). The usual specifiers are expanded in all assignments (see
+ below). Note that this setting is not only useful for attaching additional metadata to log records of a unit,
+ but given that all fields and values are indexed may also be used to implement cross-unit log record
+ matching. Assign an empty string to reset the list.</para></listitem>
</varlistentry>
<varlistentry>
<citerefentry><refentrytitle>setrlimit</refentrytitle><manvolnum>2</manvolnum></citerefentry> for details on
the resource limit concept. Resource limits may be specified in two formats: either as single value to set a
specific soft and hard limit to the same value, or as colon-separated pair <option>soft:hard</option> to set
- both limits individually (e.g. <literal>LimitAS=4G:16G</literal>). Use the string <varname>infinity</varname>
+ both limits individually (e.g. <literal>LimitAS=4G:16G</literal>). Use the string <option>infinity</option>
to configure no limit on a specific resource. The multiplicative suffixes K, M, G, T, P and E (to the base
1024) may be used for resource limits measured in bytes (e.g. LimitAS=16G). For the limits referring to time
values, the usual time units ms, s, min, h and so on may be used (see
<varname>RestrictAddressFamilies=</varname>, <varname>RestrictNamespaces=</varname>,
<varname>PrivateDevices=</varname>, <varname>ProtectKernelTunables=</varname>,
<varname>ProtectKernelModules=</varname>, <varname>MemoryDenyWriteExecute=</varname>, or
- <varname>RestrictRealtime=</varname> are specified.</para></listitem>
+ <varname>RestrictRealtime=</varname> are specified.</para>
+
+ <para>Also see
+ <ulink url="https://www.kernel.org/doc/html/latest/userspace-api/no_new_privs.html">No New Privileges Flag</ulink>.
+ </para></listitem>
</varlistentry>
<varlistentry>
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