<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>
+ <literal>%p</literal>, <literal>%P</literal>,
+ <literal>%I</literal> and <literal>%f</literal>, for
+ the full unit name, the unescaped unit name, the
+ prefix name, the unescaped prefix name, the unescaped
+ instance name and the unescaped filename,
+ respectively. The unescaped filename is either the
+ unescaped instance name (if set) with / prepended (if
+ necessary), or the prefix name similarly prepended
+ with /. The prefix name here refers to the string
+ before the @, i.e. "getty" in the example above, where
+ "tty3" is the instance name.</para>
+
+ <para>If a unit file is empty (i.e. has the file size
+ 0) or is symlinked to <filename>/dev/null</filename>
+ its configuration will not be loaded and it appears
+ with a load state of <literal>masked</literal>, and
+ cannot be activated. Use this as an effective way to
+ fully disable a unit, making it impossible to start it
+ even manually.</para>
<para>The unit file format is covered by the
<ulink
change.</para></listitem>
</varlistentry>
+ <varlistentry>
+ <term><varname>ConditionPathExists=</varname></term>
+ <term><varname>ConditionKernelCommandLine=</varname></term>
+
+ <listitem><para>Before starting a unit
+ verify that the specified condition is
+ true. With
+ <varname>ConditionPathExists=</varname>
+ a file existance condition can be
+ checked before a unit is started. If
+ the specified absolute path name does
+ not exist startup of a unit will not
+ actually happen, however the unit is
+ still useful for ordering purposes in
+ this case. The condition is checked at
+ the time the queued start job is to be
+ executed. If the absolute path name
+ passed to
+ <varname>ConditionPathExists=</varname>
+ is prefixed with an exclamation mark
+ (!), the test is negated, and the unit
+ only started if the path does not
+ exist. Similarly
+ <varname>ConditionKernelCommandLine=</varname>
+ may be used to check whether a
+ specific kernel command line option is
+ set (or if prefixed with the
+ exclamation mark unset). The argument
+ must either be a single word, or an
+ assignment (i.e. two words, seperated
+ by the equality sign). In the former
+ case the kernel command line is search
+ for the word appearing as is, or as
+ left hand side of an assignment. In
+ the latter case the exact assignment
+ is looked for with right and left hand
+ side matching. If multiple conditions
+ are specified the unit will be
+ executed iff at least one of them
+ apply (i.e. a logical OR is
+ applied).</para></listitem>
+ </varlistentry>
</variablelist>
<para>Unit file may include a [Install] section, which
~ianmdlvl / elogind.git / blobdiff