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c853953658
The handling of the command name and other arguments is unified. This simplifies things and should make them more predictable for users. Incidentally, this makes ExecStart handling match the .desktop file specification, apart for the requirment for an absolute path. https://bugs.freedesktop.org/show_bug.cgi?id=86171
1345 lines
78 KiB
XML
1345 lines
78 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
|
||
<?xml-stylesheet type="text/xsl" href="http://docbook.sourceforge.net/release/xsl/current/xhtml/docbook.xsl"?>
|
||
<!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.service">
|
||
<refentryinfo>
|
||
<title>systemd.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.service</refentrytitle>
|
||
<manvolnum>5</manvolnum>
|
||
</refmeta>
|
||
|
||
<refnamediv>
|
||
<refname>systemd.service</refname>
|
||
<refpurpose>Service unit configuration</refpurpose>
|
||
</refnamediv>
|
||
|
||
<refsynopsisdiv>
|
||
<para><filename><replaceable>service</replaceable>.service</filename></para>
|
||
</refsynopsisdiv>
|
||
|
||
<refsect1>
|
||
<title>Description</title>
|
||
|
||
<para>A unit configuration file whose name ends in
|
||
<filename>.service</filename> encodes information
|
||
about a process controlled and supervised by
|
||
systemd.</para>
|
||
|
||
<para>This man page lists the configuration options
|
||
specific to this unit type. See
|
||
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
|
||
for the common options of all unit configuration
|
||
files. The common configuration items are configured
|
||
in the generic <literal>[Unit]</literal> and
|
||
<literal>[Install]</literal> sections. The service
|
||
specific configuration options are configured in the
|
||
<literal>[Service]</literal> section.</para>
|
||
|
||
<para>Additional options are listed in
|
||
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
||
which define the execution environment the commands
|
||
are executed in, and in
|
||
<citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
||
which define the way the processes of the service are
|
||
terminated, and in
|
||
<citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
||
which configure resource control settings for the
|
||
processes of the service.</para>
|
||
|
||
<para>Unless <varname>DefaultDependencies=</varname>
|
||
is set to <option>false</option>, service units will
|
||
implicitly have dependencies of type
|
||
<varname>Requires=</varname> and
|
||
<varname>After=</varname> on
|
||
<filename>basic.target</filename> as well as
|
||
dependencies of type <varname>Conflicts=</varname> and
|
||
<varname>Before=</varname> on
|
||
<filename>shutdown.target</filename>. These ensure
|
||
that normal service units pull in basic system
|
||
initialization, and are terminated cleanly prior to
|
||
system shutdown. Only services involved with early
|
||
boot or late system shutdown should disable this
|
||
option.</para>
|
||
|
||
<para>If a service is requested under a certain name
|
||
but no unit configuration file is found, systemd looks
|
||
for a SysV init script by the same name (with the
|
||
<filename>.service</filename> suffix removed) and
|
||
dynamically creates a service unit from that
|
||
script. This is useful for compatibility with
|
||
SysV. Note that this compatibility is quite
|
||
comprehensive but not 100%. For details about the
|
||
incompatibilities, see the <ulink
|
||
url="http://www.freedesktop.org/wiki/Software/systemd/Incompatibilities">Incompatibilities
|
||
with SysV</ulink> document.
|
||
</para>
|
||
</refsect1>
|
||
|
||
<refsect1>
|
||
<title>Options</title>
|
||
|
||
<para>Service files must include a
|
||
<literal>[Service]</literal> section, which carries
|
||
information about the service and the process it
|
||
supervises. A number of options that may be used in
|
||
this section are shared with other unit types. These
|
||
options are documented in
|
||
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
|
||
and
|
||
<citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>. The
|
||
options specific to the <literal>[Service]</literal>
|
||
section of service units are the following:</para>
|
||
|
||
<variablelist class='unit-directives'>
|
||
<varlistentry>
|
||
<term><varname>Type=</varname></term>
|
||
|
||
<listitem><para>Configures the process
|
||
start-up type for this service
|
||
unit. One of <option>simple</option>,
|
||
<option>forking</option>,
|
||
<option>oneshot</option>,
|
||
<option>dbus</option>,
|
||
<option>notify</option> or
|
||
<option>idle</option>.</para>
|
||
|
||
<para>If set to
|
||
<option>simple</option> (the default
|
||
if neither
|
||
<varname>Type=</varname> nor
|
||
<varname>BusName=</varname>, but
|
||
<varname>ExecStart=</varname> are
|
||
specified), it is expected that the
|
||
process configured with
|
||
<varname>ExecStart=</varname> is the
|
||
main process of the service. In this
|
||
mode, if the process offers
|
||
functionality to other processes on
|
||
the system, its communication channels
|
||
should be installed before the daemon
|
||
is started up (e.g. sockets set up by
|
||
systemd, via socket activation), as
|
||
systemd will immediately proceed
|
||
starting follow-up units.</para>
|
||
|
||
<para>If set to
|
||
<option>forking</option>, it is
|
||
expected that the process configured
|
||
with <varname>ExecStart=</varname>
|
||
will call <function>fork()</function>
|
||
as part of its start-up. The parent process is
|
||
expected to exit when start-up is
|
||
complete and all communication
|
||
channels are set up. The child continues
|
||
to run as the main daemon
|
||
process. This is the behavior of
|
||
traditional UNIX daemons. If this
|
||
setting is used, it is recommended to
|
||
also use the
|
||
<varname>PIDFile=</varname> option, so
|
||
that systemd can identify the main
|
||
process of the daemon. systemd will
|
||
proceed with starting follow-up units
|
||
as soon as the parent process
|
||
exits.</para>
|
||
|
||
<para>Behavior of
|
||
<option>oneshot</option> is similar to
|
||
<option>simple</option>; however, it
|
||
is expected that the process has to
|
||
exit before systemd starts follow-up
|
||
units. <varname>RemainAfterExit=</varname>
|
||
is particularly useful for this type
|
||
of service. This is the implied
|
||
default if neither
|
||
<varname>Type=</varname> or
|
||
<varname>ExecStart=</varname> are
|
||
specified.</para>
|
||
|
||
<para>Behavior of
|
||
<option>dbus</option> is similar to
|
||
<option>simple</option>; however, it is
|
||
expected that the daemon acquires a
|
||
name on the D-Bus bus, as configured
|
||
by
|
||
<varname>BusName=</varname>. systemd
|
||
will proceed with starting follow-up
|
||
units after the D-Bus bus name has been
|
||
acquired. Service units with this
|
||
option configured implicitly gain
|
||
dependencies on the
|
||
<filename>dbus.socket</filename>
|
||
unit. This type is the default if
|
||
<varname>BusName=</varname> is
|
||
specified.</para>
|
||
|
||
<para>Behavior of
|
||
<option>notify</option> is similar to
|
||
<option>simple</option>; however, it is
|
||
expected that the daemon sends a
|
||
notification message via
|
||
<citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
||
or an equivalent call when it has finished
|
||
starting up. systemd will proceed with
|
||
starting follow-up units after this
|
||
notification message has been sent. If
|
||
this option is used,
|
||
<varname>NotifyAccess=</varname> (see
|
||
below) should be set to open access to
|
||
the notification socket provided by
|
||
systemd. If
|
||
<varname>NotifyAccess=</varname> is
|
||
not set, it will be implicitly set to
|
||
<option>main</option>. Note that
|
||
currently
|
||
<varname>Type=</varname><option>notify</option>
|
||
will not work if used in combination with
|
||
<varname>PrivateNetwork=</varname><option>yes</option>.</para>
|
||
|
||
<para>Behavior of
|
||
<option>idle</option> is very similar
|
||
to <option>simple</option>; however,
|
||
actual execution of the service
|
||
binary is delayed until all jobs are
|
||
dispatched. This may be used to avoid
|
||
interleaving of output of shell
|
||
services with the status output on the
|
||
console.</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>RemainAfterExit=</varname></term>
|
||
|
||
<listitem><para>Takes a boolean value
|
||
that specifies whether the service
|
||
shall be considered active even when
|
||
all its processes exited. Defaults to
|
||
<option>no</option>.</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>GuessMainPID=</varname></term>
|
||
|
||
<listitem><para>Takes a boolean value
|
||
that specifies whether systemd should
|
||
try to guess the main PID of a service
|
||
if it cannot be determined
|
||
reliably. This option is ignored
|
||
unless <option>Type=forking</option>
|
||
is set and <option>PIDFile=</option>
|
||
is unset because for the other types
|
||
or with an explicitly configured PID
|
||
file, the main PID is always known. The
|
||
guessing algorithm might come to
|
||
incorrect conclusions if a daemon
|
||
consists of more than one process. If
|
||
the main PID cannot be determined,
|
||
failure detection and automatic
|
||
restarting of a service will not work
|
||
reliably. Defaults to
|
||
<option>yes</option>.</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>PIDFile=</varname></term>
|
||
|
||
<listitem><para>Takes an absolute file
|
||
name pointing to the PID file of this
|
||
daemon. Use of this option is
|
||
recommended for services where
|
||
<varname>Type=</varname> is set to
|
||
<option>forking</option>. systemd will
|
||
read the PID of the main process of
|
||
the daemon after start-up of the
|
||
service. systemd will not write to the
|
||
file configured here.</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>BusName=</varname></term>
|
||
|
||
<listitem><para>Takes a D-Bus bus
|
||
name that this service is reachable
|
||
as. This option is mandatory for
|
||
services where
|
||
<varname>Type=</varname> is set to
|
||
<option>dbus</option>.</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>BusPolicy=</varname></term>
|
||
|
||
<listitem><para>If specified, a custom
|
||
<ulink url="https://code.google.com/p/d-bus/">kdbus</ulink>
|
||
endpoint will be created and installed as the
|
||
default bus node for the service. Such a custom
|
||
endpoint can hold an own set of policy rules
|
||
that are enforced on top of the bus-wide ones.
|
||
The custom endpoint is named after the service
|
||
it was created for, and its node will be
|
||
bind-mounted over the default bus node
|
||
location, so the service can only access the
|
||
bus through its own endpoint. Note that custom
|
||
bus endpoints default to a 'deny all' policy.
|
||
Hence, if at least one
|
||
<varname>BusPolicy=</varname> directive is
|
||
given, you have to make sure to add explicit
|
||
rules for everything the service should be able
|
||
to do.</para>
|
||
<para>The value of this directive is comprised
|
||
of two parts; the bus name, and a verb to
|
||
specify to granted access, which is one of
|
||
<option>see</option>,
|
||
<option>talk</option>, or
|
||
<option>own</option>.
|
||
<option>talk</option> implies
|
||
<option>see</option>, and <option>own</option>
|
||
implies both <option>talk</option> and
|
||
<option>see</option>.
|
||
If multiple access levels are specified for the
|
||
same bus name, the most powerful one takes
|
||
effect.
|
||
</para>
|
||
<para>Examples:</para>
|
||
<programlisting>BusPolicy=org.freedesktop.systemd1 talk</programlisting>
|
||
<programlisting>BusPolicy=org.foo.bar see</programlisting>
|
||
<para>This option is only available on kdbus enabled systems.</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>ExecStart=</varname></term>
|
||
<listitem><para>Commands with their
|
||
arguments that are executed when this
|
||
service is started. The value is split
|
||
into zero or more command lines is
|
||
according to the rules described below
|
||
(see section "Command Lines" below).
|
||
</para>
|
||
|
||
<para>When <varname>Type</varname> is
|
||
not <option>oneshot</option>, only one
|
||
command may and must be given. When
|
||
<varname>Type=oneshot</varname> is
|
||
used, zero or more commands may be
|
||
specified. This can be specified by
|
||
providing multiple command lines in
|
||
the same directive, or alternatively,
|
||
this directive may be specified more
|
||
than once with the same effect. If the
|
||
empty string is assigned to this
|
||
option, the list of commands to start
|
||
is reset, prior assignments of this
|
||
option will have no effect. If no
|
||
<varname>ExecStart=</varname> is
|
||
specified, then the service must have
|
||
<varname>RemainAfterExit=yes</varname>
|
||
set.</para>
|
||
|
||
<para>For each of the specified
|
||
commands, the first argument must be
|
||
an absolute path to an executable.
|
||
Optionally, if this file name is
|
||
prefixed with <literal>@</literal>,
|
||
the second token will be passed as
|
||
<literal>argv[0]</literal> to the
|
||
executed process, followed by the
|
||
further arguments specified. If the
|
||
absolute filename is prefixed with
|
||
<literal>-</literal>, an exit code of
|
||
the command normally considered a
|
||
failure (i.e. non-zero exit status or
|
||
abnormal exit due to signal) is
|
||
ignored and considered success. If
|
||
both <literal>-</literal> and
|
||
<literal>@</literal> are used, they
|
||
can appear in either order.</para>
|
||
|
||
<para>If more than one command is
|
||
specified, the commands are invoked
|
||
sequentially in the order they appear
|
||
in the unit file. If one of the
|
||
commands fails (and is not prefixed
|
||
with <literal>-</literal>), other
|
||
lines are not executed, and the unit
|
||
is considered failed.</para>
|
||
|
||
<para>Unless
|
||
<varname>Type=forking</varname> is
|
||
set, the process started via this
|
||
command line will be considered the
|
||
main process of the daemon.</para>
|
||
|
||
</listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>ExecStartPre=</varname></term>
|
||
<term><varname>ExecStartPost=</varname></term>
|
||
<listitem><para>Additional commands
|
||
that are executed before or after
|
||
the command in
|
||
<varname>ExecStart=</varname>, respectively.
|
||
Syntax is the same as for
|
||
<varname>ExecStart=</varname>, except
|
||
that multiple command lines are allowed
|
||
and the commands are executed one
|
||
after the other, serially.</para>
|
||
|
||
<para>If any of those commands (not
|
||
prefixed with <literal>-</literal>)
|
||
fail, the rest are not executed and
|
||
the unit is considered failed.</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>ExecReload=</varname></term>
|
||
<listitem><para>Commands to execute to
|
||
trigger a configuration reload in the
|
||
service. This argument takes multiple
|
||
command lines, following the same
|
||
scheme as described for
|
||
<varname>ExecStart=</varname>
|
||
above. Use of this setting is
|
||
optional. Specifier and environment
|
||
variable substitution is supported
|
||
here following the same scheme as for
|
||
<varname>ExecStart=</varname>.</para>
|
||
|
||
<para>One additional, special
|
||
environment variable is set: if known,
|
||
<varname>$MAINPID</varname> is set to
|
||
the main process of the daemon, and
|
||
may be used for command lines like the
|
||
following:</para>
|
||
|
||
<programlisting>/bin/kill -HUP $MAINPID</programlisting>
|
||
|
||
<para>Note however that reloading a
|
||
daemon by sending a signal (as with
|
||
the example line above) is usually not
|
||
a good choice, because this is an
|
||
asynchronous operation and hence not
|
||
suitable to order reloads of multiple
|
||
services against each other. It is
|
||
strongly recommended to set
|
||
<varname>ExecReload=</varname> to a
|
||
command that not only triggers a
|
||
configuration reload of the daemon,
|
||
but also synchronously waits for it to
|
||
complete.</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>ExecStop=</varname></term>
|
||
<listitem><para>Commands to execute to
|
||
stop the service started via
|
||
<varname>ExecStart=</varname>. This
|
||
argument takes multiple command lines,
|
||
following the same scheme as described
|
||
for <varname>ExecStart=</varname>
|
||
above. Use of this setting is
|
||
optional. After the commands configured
|
||
in this option are run, all processes
|
||
remaining for a service are
|
||
terminated according to the
|
||
<varname>KillMode=</varname> setting
|
||
(see
|
||
<citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>). If
|
||
this option is not specified, the
|
||
process is terminated immediately when
|
||
service stop is requested. Specifier
|
||
and environment variable substitution
|
||
is supported (including
|
||
<varname>$MAINPID</varname>, see
|
||
above).</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>ExecStopPost=</varname></term>
|
||
<listitem><para>Additional commands
|
||
that are executed after the service
|
||
was stopped. This includes cases where
|
||
the commands configured in
|
||
<varname>ExecStop=</varname> were used,
|
||
where the service does not have any
|
||
<varname>ExecStop=</varname> defined, or
|
||
where the service exited unexpectedly. This
|
||
argument takes multiple command lines,
|
||
following the same scheme as described
|
||
for <varname>ExecStart</varname>. Use
|
||
of these settings is
|
||
optional. Specifier and environment
|
||
variable substitution is
|
||
supported.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>RestartSec=</varname></term>
|
||
<listitem><para>Configures the time to
|
||
sleep before restarting a service (as
|
||
configured with
|
||
<varname>Restart=</varname>). Takes a
|
||
unit-less value in seconds, or a time
|
||
span value such as "5min
|
||
20s". Defaults to
|
||
100ms.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>TimeoutStartSec=</varname></term>
|
||
<listitem><para>Configures the time to
|
||
wait for start-up. If a
|
||
daemon service does not signal
|
||
start-up completion within the
|
||
configured time, the service will be
|
||
considered failed and will be shut
|
||
down again.
|
||
Takes a unit-less value in seconds, or a
|
||
time span value such as "5min
|
||
20s". Pass <literal>0</literal> to
|
||
disable the timeout logic. Defaults to
|
||
<varname>DefaultTimeoutStartSec=</varname> from
|
||
the manager configuration file, except
|
||
when <varname>Type=oneshot</varname> is
|
||
used, in which case the timeout
|
||
is disabled by default
|
||
(see <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
|
||
</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>TimeoutStopSec=</varname></term>
|
||
<listitem><para>Configures the time to
|
||
wait for stop. If a service is asked
|
||
to stop, but does not terminate in the
|
||
specified time, it will be terminated
|
||
forcibly via <constant>SIGTERM</constant>,
|
||
and after another timeout of equal duration
|
||
with <constant>SIGKILL</constant> (see
|
||
<varname>KillMode=</varname>
|
||
in <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
|
||
Takes a unit-less value in seconds, or a
|
||
time span value such as "5min
|
||
20s". Pass <literal>0</literal> to disable
|
||
the timeout logic. Defaults to
|
||
<varname>DefaultTimeoutStopSec=</varname> from the
|
||
manager configuration file
|
||
(see <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
|
||
</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>TimeoutSec=</varname></term>
|
||
<listitem><para>A shorthand for configuring
|
||
both <varname>TimeoutStartSec=</varname>
|
||
and <varname>TimeoutStopSec=</varname>
|
||
to the specified value.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>WatchdogSec=</varname></term>
|
||
<listitem><para>Configures the
|
||
watchdog timeout for a service. The
|
||
watchdog is activated when the start-up is
|
||
completed. The service must call
|
||
<citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
||
regularly with <literal>WATCHDOG=1</literal>
|
||
(i.e. the "keep-alive ping"). If the time
|
||
between two such calls is larger than
|
||
the configured time, then the service
|
||
is placed in a failed state and it will
|
||
be terminated with <varname>SIGABRT</varname>.
|
||
By setting <varname>Restart=</varname> to
|
||
<option>on-failure</option> or
|
||
<option>always</option>, the service
|
||
will be automatically restarted. The
|
||
time configured here will be passed to
|
||
the executed service process in the
|
||
<varname>WATCHDOG_USEC=</varname>
|
||
environment variable. This allows
|
||
daemons to automatically enable the
|
||
keep-alive pinging logic if watchdog
|
||
support is enabled for the service. If
|
||
this option is used,
|
||
<varname>NotifyAccess=</varname> (see
|
||
below) should be set to open access to
|
||
the notification socket provided by
|
||
systemd. If
|
||
<varname>NotifyAccess=</varname> is
|
||
not set, it will be implicitly set to
|
||
<option>main</option>. Defaults to 0,
|
||
which disables this
|
||
feature.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>Restart=</varname></term>
|
||
<listitem><para>Configures whether the
|
||
service shall be restarted when the
|
||
service process exits, is killed,
|
||
or a timeout is reached. The service
|
||
process may be the main service
|
||
process, but it may also be one of the
|
||
processes specified with
|
||
<varname>ExecStartPre=</varname>,
|
||
<varname>ExecStartPost=</varname>,
|
||
<varname>ExecStop=</varname>,
|
||
<varname>ExecStopPost=</varname>, or
|
||
<varname>ExecReload=</varname>.
|
||
When the death of the process is a
|
||
result of systemd operation (e.g. service
|
||
stop or restart), the service will not be
|
||
restarted. Timeouts include missing
|
||
the watchdog "keep-alive ping"
|
||
deadline and a service start, reload,
|
||
and stop operation timeouts.</para>
|
||
|
||
<para>Takes one of
|
||
<option>no</option>,
|
||
<option>on-success</option>,
|
||
<option>on-failure</option>,
|
||
<option>on-abnormal</option>,
|
||
<option>on-watchdog</option>,
|
||
<option>on-abort</option>, or
|
||
<option>always</option>. If set to
|
||
<option>no</option> (the default), the
|
||
service will not be restarted. If set
|
||
to <option>on-success</option>, it
|
||
will be restarted only when the
|
||
service process exits cleanly. In
|
||
this context, a clean exit means an
|
||
exit code of 0, or one of the signals
|
||
<constant>SIGHUP</constant>,
|
||
<constant>SIGINT</constant>,
|
||
<constant>SIGTERM</constant> or
|
||
<constant>SIGPIPE</constant>, and
|
||
additionally, exit statuses and
|
||
signals specified in
|
||
<varname>SuccessExitStatus=</varname>.
|
||
If set to <option>on-failure</option>,
|
||
the service will be restarted when the
|
||
process exits with a non-zero exit
|
||
code, is terminated by a signal
|
||
(including on core dump, but excluding
|
||
the aforementiond four signals), when
|
||
an operation (such as service reload)
|
||
times out, and when the configured
|
||
watchdog timeout is triggered. If set
|
||
to <option>on-abnormal</option>, the
|
||
service will be restarted when the
|
||
process is terminated by a signal
|
||
(including on core dump, excluding the
|
||
aforementioned four signals), when an
|
||
operation times out, or when the
|
||
watchdog timeout is triggered. If set
|
||
to <option>on-abort</option>, the
|
||
service will be restarted only if the
|
||
service process exits due to an
|
||
uncaught signal not specified as a
|
||
clean exit status. If set to
|
||
<option>on-watchdog</option>, the
|
||
service will be restarted only if the
|
||
watchdog timeout for the service
|
||
expires. If set to
|
||
<option>always</option>, the service
|
||
will be restarted regardless of
|
||
whether it exited cleanly or not, got
|
||
terminated abnormally by a signal, or
|
||
hit a timeout.</para>
|
||
|
||
<table>
|
||
<title>Exit causes and the effect of the <varname>Restart=</varname> settings on them</title>
|
||
|
||
<tgroup cols='2'>
|
||
<colspec colname='path' />
|
||
<colspec colname='expl' />
|
||
<thead>
|
||
<row>
|
||
<entry>Restart settings/Exit causes</entry>
|
||
<entry><option>no</option></entry>
|
||
<entry><option>always</option></entry>
|
||
<entry><option>on-success</option></entry>
|
||
<entry><option>on-failure</option></entry>
|
||
<entry><option>on-abnormal</option></entry>
|
||
<entry><option>on-abort</option></entry>
|
||
<entry><option>on-watchdog</option></entry>
|
||
</row>
|
||
</thead>
|
||
<tbody>
|
||
<row>
|
||
<entry>Clean exit code or signal</entry>
|
||
<entry/>
|
||
<entry>X</entry>
|
||
<entry>X</entry>
|
||
<entry/>
|
||
<entry/>
|
||
<entry/>
|
||
<entry/>
|
||
</row>
|
||
<row>
|
||
<entry>Unclean exit code</entry>
|
||
<entry/>
|
||
<entry>X</entry>
|
||
<entry/>
|
||
<entry>X</entry>
|
||
<entry/>
|
||
<entry/>
|
||
<entry/>
|
||
</row>
|
||
<row>
|
||
<entry>Unclean signal</entry>
|
||
<entry/>
|
||
<entry>X</entry>
|
||
<entry/>
|
||
<entry>X</entry>
|
||
<entry>X</entry>
|
||
<entry>X</entry>
|
||
<entry/>
|
||
</row>
|
||
<row>
|
||
<entry>Timeout</entry>
|
||
<entry/>
|
||
<entry>X</entry>
|
||
<entry/>
|
||
<entry>X</entry>
|
||
<entry>X</entry>
|
||
<entry/>
|
||
<entry/>
|
||
</row>
|
||
<row>
|
||
<entry>Watchdog</entry>
|
||
<entry/>
|
||
<entry>X</entry>
|
||
<entry/>
|
||
<entry>X</entry>
|
||
<entry>X</entry>
|
||
<entry/>
|
||
<entry>X</entry>
|
||
</row>
|
||
</tbody>
|
||
</tgroup>
|
||
</table>
|
||
|
||
<para>As exceptions to the setting
|
||
above the service will not be
|
||
restarted if the exit code or signal
|
||
is specified in
|
||
<varname>RestartPreventExitStatus=</varname>
|
||
(see below). Also, the services will
|
||
always be restarted if the exit code
|
||
or signal is specified in
|
||
<varname>RestartForceExitStatus=</varname>
|
||
(see below).</para>
|
||
|
||
<para>Setting this to
|
||
<option>on-failure</option> is the
|
||
recommended choice for long-running
|
||
services, in order to increase
|
||
reliability by attempting automatic
|
||
recovery from errors. For services
|
||
that shall be able to terminate on
|
||
their own choice (and avoid
|
||
immediate restarting),
|
||
<option>on-abnormal</option> is an
|
||
alternative choice.</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>SuccessExitStatus=</varname></term>
|
||
<listitem><para>Takes a list of exit
|
||
status definitions that when returned
|
||
by the main service process will be
|
||
considered successful termination, in
|
||
addition to the normal successful exit
|
||
code 0 and the signals <constant>SIGHUP</constant>, <constant>SIGINT</constant>,
|
||
<constant>SIGTERM</constant>, and <constant>SIGPIPE</constant>. Exit status
|
||
definitions can either be numeric exit
|
||
codes or termination signal names,
|
||
separated by spaces. For example:
|
||
<programlisting>SuccessExitStatus=1 2 8 SIGKILL</programlisting>
|
||
ensures that exit codes 1, 2, 8 and
|
||
the termination signal
|
||
<constant>SIGKILL</constant> are
|
||
considered clean service terminations.
|
||
</para>
|
||
|
||
<para>Note that if a process has a
|
||
signal handler installed and exits by
|
||
calling
|
||
<citerefentry><refentrytitle>_exit</refentrytitle><manvolnum>2</manvolnum></citerefentry>
|
||
in response to a signal, the
|
||
information about the signal is lost.
|
||
Programs should instead perform cleanup and kill themselves with the same signal instead. See
|
||
<ulink url="http://www.cons.org/cracauer/sigint.html">Proper handling of SIGINT/SIGQUIT — How to be a proper program</ulink>.</para>
|
||
|
||
<para>This option may appear more than once,
|
||
in which case the list of successful
|
||
exit statuses is merged. If the empty
|
||
string is assigned to this option, the
|
||
list is reset, all prior assignments
|
||
of this option will have no
|
||
effect.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>RestartPreventExitStatus=</varname></term>
|
||
<listitem><para>Takes a list of exit
|
||
status definitions that when returned
|
||
by the main service process will
|
||
prevent automatic service restarts,
|
||
regardless of the restart setting
|
||
configured with
|
||
<varname>Restart=</varname>. Exit
|
||
status definitions can either be
|
||
numeric exit codes or termination
|
||
signal names, and are separated by
|
||
spaces. Defaults to the empty list, so
|
||
that, by default, no exit status is
|
||
excluded from the configured restart
|
||
logic. For example:
|
||
<programlisting>RestartPreventExitStatus=1 6 SIGABRT</programlisting> ensures that exit
|
||
codes 1 and 6 and the termination
|
||
signal <constant>SIGABRT</constant> will
|
||
not result in automatic service
|
||
restarting. This
|
||
option may appear more than once, in
|
||
which case the list of restart-preventing
|
||
statuses is merged. If the empty
|
||
string is assigned to this option, the
|
||
list is reset and all prior assignments
|
||
of this option will have no
|
||
effect.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>RestartForceExitStatus=</varname></term>
|
||
<listitem><para>Takes a list of exit
|
||
status definitions that when returned
|
||
by the main service process will force
|
||
automatic service restarts, regardless
|
||
of the restart setting configured with
|
||
<varname>Restart=</varname>. The
|
||
argument format is similar to
|
||
<varname>RestartPreventExitStatus=</varname>.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>PermissionsStartOnly=</varname></term>
|
||
<listitem><para>Takes a boolean
|
||
argument. If true, the permission-related
|
||
execution options, as
|
||
configured with
|
||
<varname>User=</varname> and similar
|
||
options (see
|
||
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
|
||
for more information), are only applied
|
||
to the process started with
|
||
<varname>ExecStart=</varname>, and not
|
||
to the various other
|
||
<varname>ExecStartPre=</varname>,
|
||
<varname>ExecStartPost=</varname>,
|
||
<varname>ExecReload=</varname>,
|
||
<varname>ExecStop=</varname>, and
|
||
<varname>ExecStopPost=</varname>
|
||
commands. If false, the setting is
|
||
applied to all configured commands the
|
||
same way. Defaults to
|
||
false.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>RootDirectoryStartOnly=</varname></term>
|
||
<listitem><para>Takes a boolean
|
||
argument. If true, the root directory,
|
||
as configured with the
|
||
<varname>RootDirectory=</varname>
|
||
option (see
|
||
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
|
||
for more information), is only applied
|
||
to the process started with
|
||
<varname>ExecStart=</varname>, and not
|
||
to the various other
|
||
<varname>ExecStartPre=</varname>,
|
||
<varname>ExecStartPost=</varname>,
|
||
<varname>ExecReload=</varname>,
|
||
<varname>ExecStop=</varname>, and
|
||
<varname>ExecStopPost=</varname>
|
||
commands. If false, the setting is
|
||
applied to all configured commands the
|
||
same way. Defaults to
|
||
false.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>NonBlocking=</varname></term>
|
||
<listitem><para>Set the
|
||
<constant>O_NONBLOCK</constant> flag
|
||
for all file descriptors passed via
|
||
socket-based activation. If true, all
|
||
file descriptors >= 3 (i.e. all except
|
||
stdin, stdout, and stderr) will have
|
||
the <constant>O_NONBLOCK</constant> flag
|
||
set and hence are in
|
||
non-blocking mode. This option is only
|
||
useful in conjunction with a socket
|
||
unit, as described in
|
||
<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Defaults
|
||
to false.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>NotifyAccess=</varname></term>
|
||
<listitem><para>Controls access to the
|
||
service status notification socket, as
|
||
accessible via the
|
||
<citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
||
call. Takes one of
|
||
<option>none</option> (the default),
|
||
<option>main</option> or
|
||
<option>all</option>. If
|
||
<option>none</option>, no daemon status
|
||
updates are accepted from the service
|
||
processes, all status update messages
|
||
are ignored. If <option>main</option>,
|
||
only service updates sent from the
|
||
main process of the service are
|
||
accepted. If <option>all</option>, all
|
||
services updates from all members of
|
||
the service's control group are
|
||
accepted. This option should be set to
|
||
open access to the notification socket
|
||
when using
|
||
<varname>Type=notify</varname> or
|
||
<varname>WatchdogSec=</varname> (see
|
||
above). If those options are used but
|
||
<varname>NotifyAccess=</varname> is not
|
||
configured, it will be implicitly set
|
||
to
|
||
<option>main</option>.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>Sockets=</varname></term>
|
||
<listitem><para>Specifies the name of
|
||
the socket units this service shall
|
||
inherit socket file descriptors
|
||
from when the service is
|
||
started. Normally it should not be
|
||
necessary to use this setting as all
|
||
socket file descriptors whose unit
|
||
shares the same name as the service
|
||
(subject to the different unit name
|
||
suffix of course) are passed to the
|
||
spawned process.</para>
|
||
|
||
<para>Note that the same socket file
|
||
descriptors may be passed to multiple
|
||
processes simultaneously. Also note
|
||
that a different service may be
|
||
activated on incoming socket traffic
|
||
than the one which is ultimately
|
||
configured to inherit the socket file
|
||
descriptors. Or in other words: the
|
||
<varname>Service=</varname> setting of
|
||
<filename>.socket</filename> units
|
||
does not have to match the inverse of
|
||
the <varname>Sockets=</varname>
|
||
setting of the
|
||
<filename>.service</filename> it
|
||
refers to.</para>
|
||
|
||
<para>This option may appear more than
|
||
once, in which case the list of socket
|
||
units is merged. If the empty string
|
||
is assigned to this option, the list of
|
||
sockets is reset, and all prior uses of
|
||
this setting will have no
|
||
effect.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>StartLimitInterval=</varname></term>
|
||
<term><varname>StartLimitBurst=</varname></term>
|
||
|
||
<listitem><para>Configure service
|
||
start rate limiting. By default,
|
||
services which are started more
|
||
than 5 times within 10 seconds are not
|
||
permitted to start any more times
|
||
until the 10 second interval ends. With
|
||
these two options, this rate limiting
|
||
may be modified. Use
|
||
<varname>StartLimitInterval=</varname>
|
||
to configure the checking interval (defaults to
|
||
<varname>DefaultStartLimitInterval=</varname> in
|
||
manager configuration file, set to 0 to disable
|
||
any kind of rate limiting). Use
|
||
<varname>StartLimitBurst=</varname> to
|
||
configure how many starts per interval
|
||
are allowed (defaults to
|
||
<varname>DefaultStartLimitBurst=</varname> in
|
||
manager configuration file). These
|
||
configuration options are particularly
|
||
useful in conjunction with
|
||
<varname>Restart=</varname>; however,
|
||
they apply to all kinds of starts
|
||
(including manual), not just those
|
||
triggered by the
|
||
<varname>Restart=</varname> logic.
|
||
Note that units which are configured
|
||
for <varname>Restart=</varname> and
|
||
which reach the start limit are not
|
||
attempted to be restarted anymore;
|
||
however, they may still be restarted
|
||
manually at a later point, from which
|
||
point on, the restart logic is again
|
||
activated. Note that
|
||
<command>systemctl
|
||
reset-failed</command> will cause the
|
||
restart rate counter for a service to
|
||
be flushed, which is useful if the
|
||
administrator wants to manually start
|
||
a service and the start limit
|
||
interferes with
|
||
that.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>StartLimitAction=</varname></term>
|
||
|
||
<listitem><para>Configure the action
|
||
to take if the rate limit configured
|
||
with
|
||
<varname>StartLimitInterval=</varname>
|
||
and
|
||
<varname>StartLimitBurst=</varname> is
|
||
hit. Takes one of
|
||
<option>none</option>,
|
||
<option>reboot</option>,
|
||
<option>reboot-force</option>,
|
||
<option>reboot-immediate</option>,
|
||
<option>poweroff</option>,
|
||
<option>poweroff-force</option> or
|
||
<option>poweroff-immediate</option>. If
|
||
<option>none</option> is set, hitting
|
||
the rate limit will trigger no action
|
||
besides that the start will not be
|
||
permitted. <option>reboot</option>
|
||
causes a reboot following the normal
|
||
shutdown procedure (i.e. equivalent to
|
||
<command>systemctl reboot</command>).
|
||
<option>reboot-force</option> causes a
|
||
forced reboot which will terminate all
|
||
processes forcibly but should cause no
|
||
dirty file systems on reboot
|
||
(i.e. equivalent to <command>systemctl
|
||
reboot -f</command>) and
|
||
<option>reboot-immediate</option>
|
||
causes immediate execution of the
|
||
<citerefentry><refentrytitle>reboot</refentrytitle><manvolnum>2</manvolnum></citerefentry>
|
||
system call, which might result in
|
||
data loss. Similar,
|
||
<option>poweroff</option>,
|
||
<option>poweroff-force</option>,
|
||
<option>poweroff-immediate</option>
|
||
have the effect of powering down the
|
||
system with similar
|
||
semantics. Defaults to
|
||
<option>none</option>.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>FailureAction=</varname></term>
|
||
<listitem><para>Configure the action
|
||
to take when the service enters a failed
|
||
state. Takes the same values as
|
||
<varname>StartLimitAction=</varname>
|
||
and executes the same actions.
|
||
Defaults to <option>none</option>.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>RebootArgument=</varname></term>
|
||
<listitem><para>Configure the optional
|
||
argument for the
|
||
<citerefentry><refentrytitle>reboot</refentrytitle><manvolnum>2</manvolnum></citerefentry>
|
||
system call if
|
||
<varname>StartLimitAction=</varname>
|
||
or <varname>FailureAction=</varname>
|
||
is a reboot action. This works just
|
||
like the optional argument to
|
||
<command>systemctl reboot</command>
|
||
command.</para></listitem>
|
||
</varlistentry>
|
||
|
||
</variablelist>
|
||
|
||
<para>Check
|
||
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
|
||
and
|
||
<citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>
|
||
for more settings.</para>
|
||
|
||
</refsect1>
|
||
|
||
<refsect1>
|
||
<title>Command lines</title>
|
||
|
||
<para>This section describes command line parsing and
|
||
variable and specifier substitions for
|
||
<varname>ExecStart=</varname>,
|
||
<varname>ExecStartPre=</varname>,
|
||
<varname>ExecStartPost=</varname>,
|
||
<varname>ExecReload=</varname>,
|
||
<varname>ExecStop=</varname>, and
|
||
<varname>ExecStopPost=</varname> options.</para>
|
||
|
||
<para>Multiple command lines may be concatenated in a
|
||
single directive by separating them with semicolons
|
||
(these semicolons must be passed as separate words).
|
||
Lone semicolons may be escaped as
|
||
<literal>\;</literal>.</para>
|
||
|
||
<para>Each command line is split on whitespace, with
|
||
the first item being the command to execute, and the
|
||
subsequent items being the arguments. Double quotes
|
||
("...") and single quotes ('...') may be used, in
|
||
which case everything until the next matching quote
|
||
becomes part of the same argument. C-style escapes are
|
||
also supported, see table below. Quotes themselves are
|
||
removed after parsing and escape sequences
|
||
substituted. In addition, a trailing backslash
|
||
(<literal>\</literal>) may be used to merge lines.
|
||
</para>
|
||
|
||
<para>This syntax is intended to be very similar to
|
||
shell syntax, but only the meta-characters and
|
||
expansions described in the following paragraphs are
|
||
understood. Specifically, redirection using
|
||
<literal><</literal>, <literal><<</literal>,
|
||
<literal>></literal>, and
|
||
<literal>>></literal>, pipes using
|
||
<literal>|</literal>, running programs in the
|
||
background using <literal>&</literal>, and
|
||
<emphasis>other elements of shell syntax are not
|
||
supported</emphasis>.</para>
|
||
|
||
<para>The command to execute must an absolute path
|
||
name. It may contain spaces, but control characters
|
||
are not allowed.</para>
|
||
|
||
<para>The command line accepts <literal>%</literal>
|
||
specifiers as described in
|
||
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
|
||
Note that the first argument of the command line
|
||
(i.e. the program to execute) may not include
|
||
specifiers.</para>
|
||
|
||
<para>Basic environment variable substitution is
|
||
supported. Use <literal>${FOO}</literal> as part of a
|
||
word, or as a word of its own, on the command line, in
|
||
which case it will be replaced by the value of the
|
||
environment variable including all whitespace it
|
||
contains, resulting in a single argument. Use
|
||
<literal>$FOO</literal> as a separate word on the
|
||
command line, in which case it will be replaced by the
|
||
value of the environment variable split at whitespace
|
||
resulting in zero or more arguments. For this type of
|
||
expansion, quotes and respected when splitting into
|
||
words, and afterwards removed.</para>
|
||
|
||
<para>Example:</para>
|
||
|
||
<programlisting>Environment="ONE=one" 'TWO=two two'
|
||
ExecStart=/bin/echo $ONE $TWO ${TWO}</programlisting>
|
||
|
||
<para>This will execute <command>/bin/echo</command>
|
||
with four arguments: <literal>one</literal>,
|
||
<literal>two</literal>, <literal>two</literal>, and
|
||
<literal>two two</literal>.</para>
|
||
|
||
<para>Example:</para>
|
||
<programlisting>Environment=ONE='one' "TWO='two two' too" THREE=
|
||
ExecStart=/bin/echo ${ONE} ${TWO} ${THREE}
|
||
ExecStart=/bin/echo $ONE $TWO $THREE</programlisting>
|
||
<para>This results in <filename>echo</filename> being
|
||
called twice, the first time with arguments
|
||
<literal>'one'</literal>,
|
||
<literal>'two two' too</literal>, <literal></literal>,
|
||
and the second time with arguments
|
||
<literal>one</literal>, <literal>two two</literal>,
|
||
<literal>too</literal>.
|
||
</para>
|
||
|
||
<para>To pass a literal dollar sign, use
|
||
<literal>$$</literal>. Variables whose value is not
|
||
known at expansion time are treated as empty
|
||
strings. Note that the first argument (i.e. the
|
||
program to execute) may not be a variable.</para>
|
||
|
||
<para>Variables to be used in this fashion may be
|
||
defined through <varname>Environment=</varname> and
|
||
<varname>EnvironmentFile=</varname>. In addition,
|
||
variables listed in the section "Environment variables
|
||
in spawned processes" in
|
||
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
||
which are considered "static configuration", may be
|
||
used (this includes e.g. <varname>$USER</varname>, but
|
||
not <varname>$TERM</varname>).</para>
|
||
|
||
<para>Note that shell command lines are not directly
|
||
supported. If shell command lines are to be used, they
|
||
need to be passed explicitly to a shell implementation
|
||
of some kind. Example:</para>
|
||
<programlisting>ExecStart=/bin/sh -c 'dmesg | tac'</programlisting>
|
||
|
||
<para>Example:</para>
|
||
|
||
<programlisting>ExecStart=/bin/echo one ; /bin/echo "two two"</programlisting>
|
||
|
||
<para>This will execute <command>/bin/echo</command>
|
||
two times, each time with one argument:
|
||
<literal>one</literal> and <literal>two two</literal>,
|
||
respectively. Because two commands are specified,
|
||
<varname>Type=oneshot</varname> must be used.</para>
|
||
|
||
<para>Example:</para>
|
||
|
||
<programlisting>ExecStart=/bin/echo / >/dev/null & \; \
|
||
/bin/ls</programlisting>
|
||
|
||
<para>This will execute <command>/bin/echo</command>
|
||
with five arguments: <literal>/</literal>,
|
||
<literal>>/dev/null</literal>,
|
||
<literal>&</literal>, <literal>;</literal>, and
|
||
<literal>/bin/ls</literal>.</para>
|
||
|
||
<table>
|
||
<title>C escapes supported in command lines and environment variables</title>
|
||
<tgroup cols='2'>
|
||
<colspec colname='escape' />
|
||
<colspec colname='meaning' />
|
||
<thead>
|
||
<row>
|
||
<entry>Literal</entry>
|
||
<entry>Actual value</entry>
|
||
</row>
|
||
</thead>
|
||
<tbody>
|
||
<row>
|
||
<entry><literal>\a</literal></entry>
|
||
<entry>bell</entry>
|
||
</row>
|
||
<row>
|
||
<entry><literal>\b</literal></entry>
|
||
<entry>backspace</entry>
|
||
</row>
|
||
<row>
|
||
<entry><literal>\f</literal></entry>
|
||
<entry>form feed</entry>
|
||
</row>
|
||
<row>
|
||
<entry><literal>\n</literal></entry>
|
||
<entry>newline</entry>
|
||
</row>
|
||
<row>
|
||
<entry><literal>\r</literal></entry>
|
||
<entry>carriage return</entry>
|
||
</row>
|
||
<row>
|
||
<entry><literal>\t</literal></entry>
|
||
<entry>tab</entry>
|
||
</row>
|
||
<row>
|
||
<entry><literal>\v</literal></entry>
|
||
<entry>vertical tab</entry>
|
||
</row>
|
||
<row>
|
||
<entry><literal>\\</literal></entry>
|
||
<entry>backslash</entry>
|
||
</row>
|
||
<row>
|
||
<entry><literal>\"</literal></entry>
|
||
<entry>double quotation mark</entry>
|
||
</row>
|
||
<row>
|
||
<entry><literal>\'</literal></entry>
|
||
<entry>single quotation mark</entry>
|
||
</row>
|
||
<row>
|
||
<entry><literal>\s</literal></entry>
|
||
<entry>space</entry>
|
||
</row>
|
||
<row>
|
||
<entry><literal>\x<replaceable>xx</replaceable></literal></entry>
|
||
<entry>character number <replaceable>xx</replaceable> in hexadecimal encoding</entry>
|
||
</row>
|
||
<row>
|
||
<entry><literal>\<replaceable>nnn</replaceable></literal></entry>
|
||
<entry>character number <replaceable>nnn</replaceable> in octal encoding</entry>
|
||
</row>
|
||
</tbody>
|
||
</tgroup>
|
||
</table>
|
||
</refsect1>
|
||
|
||
<refsect1>
|
||
<title>See Also</title>
|
||
<para>
|
||
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
|
||
</para>
|
||
</refsect1>
|
||
|
||
</refentry>
|