run a system instance, even if the process ID is not 1, i.e.
systemd is not run as init process. <option>--user</option>
does the opposite, running a user instance even if the process
- ID is 1. Normally it should not be necessary to pass these
+ ID is 1. Normally, it should not be necessary to pass these
options, as systemd automatically detects the mode it is
started in. These options are hence of little use except for
debugging. Note that it is not supported booting and
<term><option>--crash-vt=</option><replaceable>VT</replaceable></term>
<listitem><para>Switch to a specific virtual console (VT) on
- crash. Takes a positive integer in the range 1..63, or a
+ crash. Takes a positive integer in the range 1–63, or a
boolean argument. If an integer is passed, selects which VT to
switch to. If <constant>yes</constant>, the VT kernel messages
are written to is selected. If <constant>no</constant>, no VT
<option>inherit</option>.</para></listitem>
</varlistentry>
+ <varlistentry>
+ <term><option>--machine-id=</option></term>
+
+ <listitem><para>Override the machine-id set on the hard drive,
+ useful for network booting or for containers. May not be set
+ to all zeros.</para></listitem>
+ </varlistentry>
+
<xi:include href="standard-options.xml" xpointer="help" />
<xi:include href="standard-options.xml" xpointer="version" />
</variablelist>
<title>Concepts</title>
<para>systemd provides a dependency system between various
- entities called "units" of 12 different types. Units encapsulate
+ entities called "units" of 11 different types. Units encapsulate
various objects that are relevant for system boot-up and
maintenance. The majority of units are configured in unit
configuration files, whose syntax and basic set of options is
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
however some are created automatically from other configuration,
dynamically from system state or programmatically at runtime.
- Units may be "active" (meaning started, bound, plugged in, ...,
+ Units may be "active" (meaning started, bound, plugged in, …,
depending on the unit type, see below), or "inactive" (meaning
- stopped, unbound, unplugged, ...), as well as in the process of
+ stopped, unbound, unplugged, …), as well as in the process of
being activated or deactivated, i.e. between the two states (these
states are called "activating", "deactivating"). A special
"failed" state is available as well, which is very similar to
<orderedlist>
<listitem><para>Service units, which start and control daemons
- and the processes they consist of. For details see
+ and the processes they consist of. For details, see
<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
<listitem><para>Socket units, which encapsulate local IPC or
network sockets in the system, useful for socket-based
- activation. For details about socket units see
+ activation. For details about socket units, see
<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
for details on socket-based activation and other forms of
activation, see
<listitem><para>Device units expose kernel devices in systemd
and may be used to implement device-based activation. For
- details see
+ details, see
<citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
<listitem><para>Mount units control mount points in the file
boot-up. See
<citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
- <listitem><para>Snapshot units can be used to temporarily save
- the state of the set of systemd units, which later may be
- restored by activating the saved snapshot unit. For more
- information see
- <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
-
<listitem><para>Timer units are useful for triggering activation
of other units based on timers. You may find details in
<citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
<para>On boot systemd activates the target unit
<filename>default.target</filename> whose job is to activate
on-boot services and other on-boot units by pulling them in via
- dependencies. Usually the unit name is just an alias (symlink) for
+ dependencies. Usually, the unit name is just an alias (symlink) for
either <filename>graphical.target</filename> (for fully-featured
boots into the UI) or <filename>multi-user.target</filename> (for
limited console-only boots for use in embedded or server
<para>Units may be generated dynamically at boot and system
manager reload time, for example based on other configuration
- files or parameters passed on the kernel command line. For details see
+ files or parameters passed on the kernel command line. For details, see
<citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
<para>Systems which invoke systemd in a container or initrd
<filename>ctrl-alt-del.target</filename> unit. This is mostly
equivalent to <command>systemctl start
ctl-alt-del.target</command>. If this signal is received more
- often than 7 times per 2s an immediate reboot is triggered.
+ than 7 times per 2s, an immediate reboot is triggered.
Note that pressing Ctrl-Alt-Del on the console will trigger
- this signal. Hence, if a reboot is hanging pressing
+ this signal. Hence, if a reboot is hanging, pressing
Ctrl-Alt-Del more than 7 times in 2s is a relatively safe way
to trigger an immediate reboot.</para>
<term><constant>SIGUSR2</constant></term>
<listitem><para>When this signal is received the systemd
- manager will log its complete state in human readable form.
+ manager will log its complete state in human-readable form.
The data logged is the same as printed by
<command>systemd-analyze dump</command>.</para></listitem>
</varlistentry>
script runlevel link farms.</para></listitem>
</varlistentry>
+ <varlistentry>
+ <term><varname>$SYSTEMD_COLORS</varname></term>
+
+ <listitem><para>The value must be a boolean. Controls whether colorized output should be
+ generated. This can be specified to override the decision that <command>systemd</command>
+ makes based on <varname>$TERM</varname> and what the console is connected to.</para>
+ </listitem>
+ </varlistentry>
+
<varlistentry>
<term><varname>$LISTEN_PID</varname></term>
<term><varname>$LISTEN_FDS</varname></term>
<listitem><para>Set by systemd for supervised processes during
socket-based activation. See
<citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>
- for more information. </para></listitem>
+ for more information.</para></listitem>
</varlistentry>
<varlistentry>
<listitem><para>Set by systemd for supervised processes for
status and start-up completion notification. See
<citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
- for more information. </para></listitem>
+ for more information.</para></listitem>
</varlistentry>
</variablelist>
</refsect1>
<term><varname>systemd.crash_chvt=</varname></term>
<listitem><para>Takes a positive integer, or a boolean
- argument. If a positive integer (in the range 1..63) is
- specified the system manager (PID 1) will activate the specified
+ argument. If a positive integer (in the range 1–63) is
+ specified, the system manager (PID 1) will activate the specified
virtual terminal (VT) when it crashes. Defaults to
<constant>no</constant>, meaning that no such switch is
- attempted. If set to <constant>yes</constant> the VT the
+ attempted. If set to <constant>yes</constant>, the VT the
kernel messages are written to is selected.</para></listitem>
</varlistentry>
the machine automatically when it crashes, after a 10s delay.
Otherwise, the system will hang indefinitely. Defaults to
<option>no</option>, in order to avoid a reboot loop. If
- combined with <varname>systemd.crash_shell=</varname>, it is
- first attempted to invoke a shell, and if this is not
- successful the system is rebooted.</para></listitem>
+ combined with <varname>systemd.crash_shell=</varname>, the
+ system is rebooted after the shell exits.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>systemd.confirm_spawn=</varname></term>
- <listitem><para>Takes a boolean argument. If
- <option>yes</option>, the system manager (PID 1) asks for
- confirmation when spawning processes. Defaults to
- <option>no</option>.</para></listitem>
+ <listitem><para>Takes a boolean argument or a path to the
+ virtual console where the confirmation messages should be
+ emitted. If <option>yes</option>, the system manager (PID 1)
+ asks for confirmation when spawning processes using
+ <option>/dev/console</option>. If a path or a console name
+ (such as <literal>ttyS0</literal>) is provided, the virtual
+ console pointed to by this path or described by the give name
+ will be used instead. Defaults to <option>no</option>.</para></listitem>
</varlistentry>
<varlistentry>
like <option>false</option> until a service fails or there is
a significant delay in boot. Defaults to
<option>yes</option>, unless <option>quiet</option> is passed
- as kernel command line option in which case it defaults to
+ as kernel command line option, in which case it defaults to
<constant>auto</constant>.</para></listitem>
</varlistentry>
than once to set multiple variables.</para></listitem>
</varlistentry>
+ <varlistentry>
+ <term><varname>systemd.machine_id=</varname></term>
+
+ <listitem><para>Takes a 32 character hex value to be
+ used for setting the machine-id. Intended mostly for
+ network booting where the same machine-id is desired
+ for every boot.</para></listitem>
+ </varlistentry>
+
<varlistentry>
<term><varname>quiet</varname></term>
<varlistentry>
<term><varname>emergency</varname></term>
+ <term><varname>rd.emergency</varname></term>
<term><varname>-b</varname></term>
<listitem><para>Boot into emergency mode. This is equivalent
- to <varname>systemd.unit=emergency.target</varname> and
- provided for compatibility reasons and to be easier to
- type.</para></listitem>
+ to <varname>systemd.unit=emergency.target</varname> or
+ <varname>rd.systemd.unit=emergency.target</varname>, respectively, and
+ provided for compatibility reasons and to be easier to type.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>rescue</varname></term>
+ <term><varname>rd.rescue</varname></term>
<term><varname>single</varname></term>
<term><varname>s</varname></term>
<term><varname>S</varname></term>
<term><varname>1</varname></term>
<listitem><para>Boot into rescue mode. This is equivalent to
- <varname>systemd.unit=rescue.target</varname> and provided for
- compatibility reasons and to be easier to
- type.</para></listitem>
+ <varname>systemd.unit=rescue.target</varname> or
+ <varname>rd.systemd.unit=rescue.target</varname>, respectively, and
+ provided for compatibility reasons and to be easier to type.</para></listitem>
</varlistentry>
<varlistentry>
<listitem><para>Set the system locale to use. This overrides
the settings in <filename>/etc/locale.conf</filename>. For
- more information see
+ more information, see
<citerefentry project='man-pages'><refentrytitle>locale.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
and
<citerefentry project='man-pages'><refentrytitle>locale</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
projects / thirdparty / systemd.git / blobdiff