- with @, the second token will be
- passed as argv[0] to the executed
- process, followed by the further
- arguments specified. Unless
- <option>Type=forking</option> is set,
- the process started via this command
- line will be considered the main
- process of the
- daemon.</para></listitem>
+ 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
+ first token is prefixed with
+ <literal>-</literal> an error code of
+ the command normally considered a
+ failure is ignored and considered
+ success. If both <literal>-</literal>
+ and <literal>@</literal> are used for
+ the same command the latter must
+ preceed the latter. Unless
+ <varname>Type=forking</varname> is
+ set, the process started via this
+ command line will be considered the
+ main process of the daemon. The
+ command line accepts % specifiers as
+ described in
+ <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. On
+ top of that basic environment variable
+ substitution is supported, where
+ <literal>${FOO}</literal> is replaced
+ by the string value of the environment
+ variable of the same name. Also
+ <literal>$FOO</literal> may appear as
+ seperate word on the command line in
+ which case the variable is replaced by
+ its value split at
+ whitespaces.</para></listitem>