<filename>systemd.swap</filename>,
<filename>systemd.target</filename>,
<filename>systemd.path</filename>,
- <filename>systemd.timer</filename></para>
+ <filename>systemd.timer</filename>,
+ <filename>systemd.snapshot</filename></para>
</refsynopsisdiv>
<refsect1>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>. The
syntax is inspired by <ulink
url="http://standards.freedesktop.org/desktop-entry-spec/latest/">XDG
- Desktop Entry Specificiation</ulink> <filename>.desktop</filename> files, which are in turn
+ Desktop Entry Specification</ulink> <filename>.desktop</filename> files, which are in turn
inspired by Microsoft Windows
<filename>.ini</filename> files.</para>
<para>This man pages lists the common configuration
- options of the all unit types. These options need to
+ options of all the unit types. These options need to
be configured in the [Unit] resp. [Install]
section of the unit files.</para>
<para>In addition to the generic [Unit] and [Install]
- sections described here each unit should have a
+ sections described here, each unit should have a
type-specific section, e.g. [Service] for a service
unit. See the respective man pages for more
information.</para>
additional information in the unit files.</para>
<para>Boolean arguments used in unit files can be
- written in various forms. For positive settings the
+ written in various formats. For positive settings the
strings <option>1</option>, <option>yes</option>,
<option>true</option> and <option>on</option> are
equivalent. For negative settings the strings
<option>false</option> and <option>off</option> are
equivalent.</para>
+ <para>Time span values encoded in unit files can be
+ written in various formats. A stand-alone number
+ specifies a time in seconds. If suffixed with a time
+ unit, the unit is honored. A concatenation of
+ multiple values with units is supported, in which case
+ the values are added up. Example: "50" refers to 50
+ seconds; "2min 200ms" refers to 2 minutes plus 200
+ milliseconds, i.e. 120200ms. The following time units
+ are understood: s, min, h, d, w, ms, us.</para>
+
<para>Empty lines and lines starting with # or ; are
- ignored. This may be used for commenting.</para>
+ ignored. This may be used for commenting. Lines ending
+ in a backslash are concatenated with the following
+ line while reading and the backslash is replaced by a
+ space character. This may be used to wrap long lines.</para>
<para>If a line starts with <option>.include</option>
- followed by a file name the specified file will be
- read as if its contents where listed in place of the
+ followed by a file name, the specified file will be
+ read as if its contents were listed in place of the
<option>.include</option> directive.</para>
<para>Along with a unit file
activation which makes dependencies implicit, which
both results in a simpler and more flexible
system.</para>
+
+ <para>Some unit names reflect paths existing in the
+ file system name space. Example: a device unit
+ <filename>dev-sda.device</filename> refers to a device
+ with the device node <filename>/dev/sda</filename> in
+ the file system namespace. If this applies a special
+ way to escape the path name is used, so that it is
+ usable as part of a file name. Basically, given a
+ path, "/" is replaced by "-", and all unprintable
+ characters and the "-" are replaced by C-style "\x20"
+ escapes. The root directory "/" is encoded as single
+ dash, while otherwise the initial and ending "/" is
+ removed from all paths during transformation. This
+ escaping is reversible.</para>
+
+ <para>Optionally, units may be instantiated from a
+ template file at runtime. This allows creation of
+ multiple units from a single configuration file. If
+ systemd looks for a unit configuration file it will
+ first search for the literal unit name in the
+ filesystem. If that yields no success and the unit
+ name contains an @ character, systemd will look for a
+ unit template that shares the same name but with the
+ instance string (i.e. the part between the @ character
+ and the suffix) removed. Example: if a service
+ <filename>getty@tty3.service</filename> is requested
+ and no file by that name is found, systemd will look
+ for <filename>getty@.service</filename> and
+ instantiate a service from that configuration file if
+ it is found. To refer to the instance string from
+ within the configuration file you may use the special
+ <literal>%i</literal> specifier in many of the
+ configuration options. Other specifiers that may be
+ used are <literal>%n</literal>, <literal>%N</literal>,
+ <literal>%p</literal>, <literal>%P</literal> and
+ <literal>%I</literal>, for the full unit name, the
+ unescaped unit name, the prefix name, the unescaped
+ prefix name and the unescaped instance name,
+ respectively. The prefix name here refers to the
+ string before the @, i.e. "getty" in the example
+ above, where "tty3" is the instance name.</para>
</refsect1>
<refsect1>
<varlistentry>
<term><varname>Description=</varname></term>
<listitem><para>A free-form string
- describing the unit. This is intended for use
- in UIs wanting to show
- descriptive information along with the
- unit name.</para></listitem>
+ describing the unit. This is intended
+ for use in UIs to show descriptive
+ information along with the unit
+ name.</para></listitem>
</varlistentry>
<varlistentry>
<listitem><para>Configures requirement
dependencies on other units. If this
- units get activated the units listed
+ unit gets activated, the units listed
here will be activated as well. If one
of the other units gets deactivated or
its activation fails, this unit will
Dependencies listed in
<varname>RequiresOverridable=</varname>
which cannot be fulfilled or fail to
- start are ignored iff the startup was
+ start are ignored if the startup was
explicitly requested by the user. If
the start-up was pulled in indirectly
by some dependency or automatic
must be fulfilled and otherwise the
transaction fails. Hence, this option
may be used to configure dependencies
- that are normally honoured unless the
+ that are normally honored unless the
user explicitly starts up the unit, in
which case whether they failed or not
is irrelevant.</para></listitem>
<varname>Requires=</varname>. A unit
listed in this option will be started
if the configuring unit is. However,
- it the listed unit fails to start up
+ if the listed unit fails to start up
or cannot be added to the transaction
this has no impact on the validity of
the transaction as a whole. This is
<listitem><para>Configures negative
requirement dependencies. If a unit
- that has a
+ has a
<varname>Conflicts=</varname> setting
- on another unit starting the former
+ on another unit, starting the former
will stop the latter and vice
versa. Note that this setting is
independent of and orthogonal to the
<filename>foo.service</filename>
contains a setting
<option>Before=bar.service</option>
- and both units are being started
+ and both units are being started,
<filename>bar.service</filename>'s
start-up is delayed until
<filename>foo.service</filename> is
listed unit is started. Note that when
two units with an ordering dependency
between them are shut down, the
- inverse of of the start-up order is
+ inverse of the start-up order is
applied. i.e. if a unit is configured
with <varname>After=</varname> on
another unit, the former is stopped
<listitem><para>Takes a boolean
argument. If <option>true</option> and
- the unit stops without this being
- requested by the user all units
+ the unit stops without being requested
+ by the user, all units
depending on it will be stopped as
well. (e.g. if a service exits or
crashes on its own behalf, units using
it will be stopped) Note that normally
- if a unit stops without user request
+ if a unit stops without a user request,
units depending on it will not be
terminated. Only if the user requested
- shutdown of a unit all units depending
- on the unit will be shut down as well
+ shutdown of a unit, all units depending
+ on that unit will be shut down as well
and at the same time. Defaults to
<option>false</option>.</para></listitem>
</varlistentry>
argument. If <option>true</option>
this unit will be stopped when it is
no longer used. Note that in order to
- minimize the work to be executed
- systemd will by default not stop units
+ minimize the work to be executed,
+ systemd will not stop units by default
unless they are conflicting with other
units, or the user explicitly
requested their shut down. If this
- option is set a unit will be
+ option is set, a unit will be
automatically cleaned up if no other
active unit requires it. Defaults to
<option>false</option>.</para></listitem>
<listitem><para>Takes a boolean
argument. If <option>true</option>
- this unit may only be activated
+ this unit can only be activated
indirectly. In this case explicit
start-up requested by the user is
- denied, however if it is started as
- dependency of another unit start-up
+ denied, however if it is started as a
+ dependency of another unit, start-up
will succeed. This is mostly a safety
feature to ensure that the user does
- not accidently activate units that are
+ not accidentally activate units that are
not intended to be activated
explicitly. This option defaults to
<option>false</option>.</para></listitem>
</varlistentry>
+ <varlistentry>
+ <term><varname>DefaultDependencies=</varname></term>
+
+ <listitem><para>Takes a boolean
+ argument. If <option>true</option>
+ (the default), a few default
+ dependencies will implicitly be
+ created for the unit. The actual
+ dependencies created depend on the
+ unit type. For example, for service
+ units, these dependencies ensure that
+ the service is started only after
+ basic system initialization is
+ completed and is properly terminated on
+ system shutdown. See the respective
+ man pages for details. Generally, only
+ services involved with early boot or
+ late shutdown should set this option
+ to <option>false</option>. It is
+ highly recommended to leave this
+ option enabled for the majority of
+ common units. If set to
+ <option>false</option> this option
+ does not disable all implicit
+ dependencies, just non-essential
+ ones.</para></listitem>
+ </varlistentry>
+
</variablelist>
<para>Unit file may include a [Install] section, which
name. This option may be specified
more than once, in which case all
listed names are used. At installation
- time
+ time,
<command>systemd-install</command>
will create symlinks from these names
to the unit file name. Note that this
effect that when the listed unit name
is activated the unit listing it is
activated
- to. <command>WantedBy=foo.service</command>
+ too. <command>WantedBy=foo.service</command>
in a service
<filename>bar.service</filename> is
mostly equivalent to
install when this unit is
installed. If the user requests
installation of a unit with this
- option configured
+ option configured,
<command>systemd-install</command>
will automatically install units
listed in this option as
<citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>
</para>
</refsect1>
~ianmdlvl / elogind.git / blobdiff