path: root/man/systemd-system.conf.xml

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<refentry id="systemd-system.conf"
    xmlns:xi="http://www.w3.org/2001/XInclude">
  <refentryinfo>
    <title>systemd-system.conf</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-system.conf</refentrytitle>
    <manvolnum>5</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>systemd-system.conf</refname>
    <refname>system.conf.d</refname>
    <refname>systemd-user.conf</refname>
    <refname>user.conf.d</refname>
    <refpurpose>System and session service manager configuration files</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <para><filename>/etc/systemd/system.conf</filename>,
    <filename>/etc/systemd/system.conf.d/*.conf</filename>,
    <filename>/run/systemd/system.conf.d/*.conf</filename>,
    <filename>/usr/lib/systemd/system.conf.d/*.conf</filename></para>
    <para><filename>/etc/systemd/user.conf</filename>,
    <filename>/etc/systemd/user.conf.d/*.conf</filename>,
    <filename>/run/systemd/user.conf.d/*.conf</filename>,
    <filename>/usr/lib/systemd/user.conf.d/*.conf</filename></para>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para>When run as a system instance, systemd interprets the
    configuration file <filename>system.conf</filename> and the files
    in <filename>system.conf.d</filename> directories; when run as a
    user instance, systemd interprets the configuration file
    <filename>user.conf</filename> and the files in
    <filename>user.conf.d</filename> directories. These configuration
    files contain a few settings controlling basic manager
    operations.</para>
  </refsect1>

  <xi:include href="standard-conf.xml" xpointer="main-conf" />

  <refsect1>
    <title>Options</title>

    <para>All options are configured in the
    <literal>[Manager]</literal> section:</para>

    <variablelist class='systemd-directives'>

      <varlistentry>
        <term><varname>LogLevel=</varname></term>
        <term><varname>LogTarget=</varname></term>
        <term><varname>LogColor=</varname></term>
        <term><varname>LogLocation=</varname></term>
        <term><varname>DumpCore=yes</varname></term>
        <term><varname>CrashChangeVT=no</varname></term>
        <term><varname>CrashShell=no</varname></term>
        <term><varname>CrashReboot=no</varname></term>
        <term><varname>ShowStatus=yes</varname></term>
        <term><varname>DefaultStandardOutput=journal</varname></term>
        <term><varname>DefaultStandardError=inherit</varname></term>

        <listitem><para>Configures various parameters of basic manager operation. These options may be overridden by
        the respective process and kernel command line arguments. See
        <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry> for
        details.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>CtrlAltDelBurstAction=</varname></term>

        <listitem><para>Defines what action will be performed
        if user presses Ctrl-Alt-Delete more than 7 times in 2s.
        Can be set to <literal>reboot-force</literal>, <literal>poweroff-force</literal>,
        <literal>reboot-immediate</literal>, <literal>poweroff-immediate</literal>
        or disabled with <literal>none</literal>. Defaults to
        <literal>reboot-force</literal>.
        </para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>CPUAffinity=</varname></term>

        <listitem><para>Configures the initial CPU affinity for the
        init process. Takes a list of CPU indices or ranges separated
        by either whitespace or commas. CPU ranges are specified by
        the lower and upper CPU indices separated by a
        dash.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>JoinControllers=cpu,cpuacct net_cls,netprio</varname></term>

        <listitem><para>Configures controllers that shall be mounted
        in a single hierarchy. By default, systemd will mount all
        controllers which are enabled in the kernel in individual
        hierarchies, with the exception of those listed in this
        setting. Takes a space-separated list of comma-separated
        controller names, in order to allow multiple joined
        hierarchies. Defaults to 'cpu,cpuacct'. Pass an empty string
        to ensure that systemd mounts all controllers in separate
        hierarchies.</para>

        <para>Note that this option is only applied once, at very
        early boot. If you use an initial RAM disk (initrd) that uses
        systemd, it might hence be necessary to rebuild the initrd if
        this option is changed, and make sure the new configuration
        file is included in it. Otherwise, the initrd might mount the
        controller hierarchies in a different configuration than
        intended, and the main system cannot remount them
        anymore.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>RuntimeWatchdogSec=</varname></term>
        <term><varname>ShutdownWatchdogSec=</varname></term>

        <listitem><para>Configure the hardware watchdog at runtime and at reboot. Takes a timeout value in seconds (or
        in other time units if suffixed with <literal>ms</literal>, <literal>min</literal>, <literal>h</literal>,
        <literal>d</literal>, <literal>w</literal>). If <varname>RuntimeWatchdogSec=</varname> is set to a non-zero
        value, the watchdog hardware (<filename>/dev/watchdog</filename> or the path specified with
        <varname>WatchdogDevice=</varname> or the kernel option <varname>systemd.watchdog-device=</varname>) will be
        programmed to automatically reboot the system if it is not contacted within the specified timeout interval. The
        system manager will ensure to contact it at least once in half the specified timeout interval. This feature
        requires a hardware watchdog device to be present, as it is commonly the case in embedded and server
        systems. Not all hardware watchdogs allow configuration of all possible reboot timeout values, in which case
        the closest available timeout is picked. <varname>ShutdownWatchdogSec=</varname> may be used to configure the
        hardware watchdog when the system is asked to reboot. It works as a safety net to ensure that the reboot takes
        place even if a clean reboot attempt times out. Note that the <varname>ShutdownWatchdogSec=</varname> timeout
        applies only to the second phase of the reboot, i.e. after all regular services are already terminated, and
        after the system and service manager process (PID 1) got replaced by the <filename>systemd-shutdown</filename>
        binary, see system <citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>
        for details. During the first phase of the shutdown operation the system and service manager remains running
        and hence <varname>RuntimeWatchdogSec=</varname> is still honoured. In order to define a timeout on this first
        phase of system shutdown, configure <varname>JobTimeoutSec=</varname> and <varname>JobTimeoutAction=</varname>
        in the <literal>[Unit]</literal> section of the <filename>shutdown.target</filename> unit. By default
        <varname>RuntimeWatchdogSec=</varname> defaults to 0 (off), and <varname>ShutdownWatchdogSec=</varname> to
        10min. These settings have no effect if a hardware watchdog is not available.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>WatchdogDevice=</varname></term>

        <listitem><para>Configure the hardware watchdog device that the
        runtime and shutdown watchdog timers will open and use. Defaults
        to <filename>/dev/watchdog</filename>. This setting has no
        effect if a hardware watchdog is not available.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>CapabilityBoundingSet=</varname></term>

        <listitem><para>Controls which capabilities to include in the
        capability bounding set for PID 1 and its children. See
        <citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
        for details. Takes a whitespace-separated list of capability
        names as read by
        <citerefentry project='mankier'><refentrytitle>cap_from_name</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
        Capabilities listed will be included in the bounding set, all
        others are removed. If the list of capabilities is prefixed
        with ~, all but the listed capabilities will be included, the
        effect of the assignment inverted. Note that this option also
        affects the respective capabilities in the effective,
        permitted and inheritable capability sets. The capability
        bounding set may also be individually configured for units
        using the <varname>CapabilityBoundingSet=</varname> directive
        for units, but note that capabilities dropped for PID 1 cannot
        be regained in individual units, they are lost for
        good.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>NoNewPrivileges=</varname></term>

        <listitem><para>Takes a boolean argument. If true, ensures that PID 1
        and all its children can never gain new privileges through
        <citerefentry project='man-pages'><refentrytitle>execve</refentrytitle><manvolnum>2</manvolnum></citerefentry>
        (e.g. via setuid or setgid bits, or filesystem capabilities).
        Defaults to false. General purpose distributions commonly rely
        on executables with setuid or setgid bits and will thus not
        function properly with this option enabled. Individual units
        cannot disable this option.
        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>
        <term><varname>SystemCallArchitectures=</varname></term>

        <listitem><para>Takes a space-separated list of architecture
        identifiers. Selects from which architectures system calls may
        be invoked on this system. This may be used as an effective
        way to disable invocation of non-native binaries system-wide,
        for example to prohibit execution of 32-bit x86 binaries on
        64-bit x86-64 systems. This option operates system-wide, and
        acts similar to the
        <varname>SystemCallArchitectures=</varname> setting of unit
        files, see
        <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
        for details. This setting defaults to the empty list, in which
        case no filtering of system calls based on architecture is
        applied. Known architecture identifiers are
        <literal>x86</literal>, <literal>x86-64</literal>,
        <literal>x32</literal>, <literal>arm</literal> and the special
        identifier <literal>native</literal>. The latter implicitly
        maps to the native architecture of the system (or more
        specifically, the architecture the system manager was compiled
        for). Set this setting to <literal>native</literal> to
        prohibit execution of any non-native binaries. When a binary
        executes a system call of an architecture that is not listed
        in this setting, it will be immediately terminated with the
        SIGSYS signal.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>TimerSlackNSec=</varname></term>

        <listitem><para>Sets the timer slack in nanoseconds for PID 1,
        which is inherited by all executed processes, unless
        overridden individually, for example with the
        <varname>TimerSlackNSec=</varname> setting in service units
        (for details see
        <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
        The timer slack controls the accuracy of wake-ups triggered by
        system timers. See
        <citerefentry><refentrytitle>prctl</refentrytitle><manvolnum>2</manvolnum></citerefentry>
        for more information. Note that in contrast to most other time
        span definitions this parameter takes an integer value in
        nano-seconds if no unit is specified. The usual time units are
        understood too.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DefaultTimerAccuracySec=</varname></term>

        <listitem><para>Sets the default accuracy of timer units. This
        controls the global default for the
        <varname>AccuracySec=</varname> setting of timer units, see
        <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>
        for details. <varname>AccuracySec=</varname> set in individual
        units override the global default for the specific unit.
        Defaults to 1min. Note that the accuracy of timer units is
        also affected by the configured timer slack for PID 1, see
        <varname>TimerSlackNSec=</varname> above.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DefaultTimeoutStartSec=</varname></term>
        <term><varname>DefaultTimeoutStopSec=</varname></term>
        <term><varname>DefaultRestartSec=</varname></term>

        <listitem><para>Configures the default timeouts for starting
        and stopping of units, as well as the default time to sleep
        between automatic restarts of units, as configured per-unit in
        <varname>TimeoutStartSec=</varname>,
        <varname>TimeoutStopSec=</varname> and
        <varname>RestartSec=</varname> (for services, see
        <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
        for details on the per-unit settings). For non-service units,
        <varname>DefaultTimeoutStartSec=</varname> sets the default
        <varname>TimeoutSec=</varname>
        value. <varname>DefaultTimeoutStartSec=</varname> and
        <varname>DefaultTimeoutStopSec=</varname> default to
        90s. <varname>DefaultRestartSec=</varname> defaults to
        100ms.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DefaultStartLimitIntervalSec=</varname></term>
        <term><varname>DefaultStartLimitBurst=</varname></term>

        <listitem><para>Configure the default unit start rate
        limiting, as configured per-service by
        <varname>StartLimitIntervalSec=</varname> and
        <varname>StartLimitBurst=</varname>. See
        <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
        for details on the per-service settings.
        <varname>DefaultStartLimitIntervalSec=</varname> defaults to
        10s. <varname>DefaultStartLimitBurst=</varname> defaults to
        5.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DefaultEnvironment=</varname></term>

        <listitem><para>Sets manager environment variables passed to
        all executed processes. Takes a space-separated list of
        variable assignments. See
        <citerefentry project='man-pages'><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry>
        for details about environment variables.</para>

        <para>Example:

        <programlisting>DefaultEnvironment="VAR1=word1 word2" VAR2=word3 "VAR3=word 5 6"</programlisting>

        Sets three variables
        <literal>VAR1</literal>,
        <literal>VAR2</literal>,
        <literal>VAR3</literal>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DefaultCPUAccounting=</varname></term>
        <term><varname>DefaultBlockIOAccounting=</varname></term>
        <term><varname>DefaultMemoryAccounting=</varname></term>
        <term><varname>DefaultTasksAccounting=</varname></term>
        <term><varname>DefaultIPAccounting=</varname></term>

        <listitem><para>Configure the default resource accounting settings, as configured per-unit by
        <varname>CPUAccounting=</varname>, <varname>BlockIOAccounting=</varname>, <varname>MemoryAccounting=</varname>,
        <varname>TasksAccounting=</varname> and <varname>IPAccounting=</varname>. See
        <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>
        for details on the per-unit settings. <varname>DefaultTasksAccounting=</varname> defaults to on,
        <varname>DefaultMemoryAccounting=</varname> to &MEMORY_ACCOUNTING_DEFAULT;,
        the other three settings to off.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DefaultTasksMax=</varname></term>

        <listitem><para>Configure the default value for the per-unit <varname>TasksMax=</varname> setting. See
        <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>
        for details. This setting applies to all unit types that support resource control settings, with the exception
        of slice units. Defaults to 15%, which equals 4915 with the kernel's defaults on the host, but might be smaller
        in OS containers.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DefaultLimitCPU=</varname></term>
        <term><varname>DefaultLimitFSIZE=</varname></term>
        <term><varname>DefaultLimitDATA=</varname></term>
        <term><varname>DefaultLimitSTACK=</varname></term>
        <term><varname>DefaultLimitCORE=</varname></term>
        <term><varname>DefaultLimitRSS=</varname></term>
        <term><varname>DefaultLimitNOFILE=</varname></term>
        <term><varname>DefaultLimitAS=</varname></term>
        <term><varname>DefaultLimitNPROC=</varname></term>
        <term><varname>DefaultLimitMEMLOCK=</varname></term>
        <term><varname>DefaultLimitLOCKS=</varname></term>
        <term><varname>DefaultLimitSIGPENDING=</varname></term>
        <term><varname>DefaultLimitMSGQUEUE=</varname></term>
        <term><varname>DefaultLimitNICE=</varname></term>
        <term><varname>DefaultLimitRTPRIO=</varname></term>
        <term><varname>DefaultLimitRTTIME=</varname></term>

        <listitem><para>These settings control various default
        resource limits for units. See
        <citerefentry><refentrytitle>setrlimit</refentrytitle><manvolnum>2</manvolnum></citerefentry>
        for details. The resource limit is possible to specify in two formats,
        <option>value</option> to set soft and hard limits to the same value,
        or <option>soft:hard</option> to set both limits individually (e.g. DefaultLimitAS=4G:16G).
        Use the string <varname>infinity</varname> to
        configure no limit on a specific resource. The multiplicative
        suffixes K (=1024), M (=1024*1024) and so on for G, T, P and E
        may be used for resource limits measured in bytes
        (e.g. DefaultLimitAS=16G). For the limits referring to time values,
        the usual time units ms, s, min, h and so on may be used (see
        <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>
        for details). Note that if no time unit is specified for
        <varname>DefaultLimitCPU=</varname> the default unit of seconds is
        implied, while for <varname>DefaultLimitRTTIME=</varname> the default
        unit of microseconds is implied. Also, note that the effective
        granularity of the limits might influence their
        enforcement. For example, time limits specified for
        <varname>DefaultLimitCPU=</varname> will be rounded up implicitly to
        multiples of 1s. These  settings may be overridden in individual units
        using the corresponding LimitXXX= directives. Note that these resource
        limits are only defaults for units, they are not applied to PID 1
        itself.</para></listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
      <title>See Also</title>
      <para>
        <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
        <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
        <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
        <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
        <citerefentry project='man-pages'><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
        <citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
      </para>
  </refsect1>

</refentry>