- <literal>$(FOO)</literal> is replaced
- by the value of the environment
- variable of the same
- name.</para></listitem>
+ <literal>${FOO}</literal> is replaced
+ by the string value of the environment
+ variable of the same name. Also
+ <literal>$FOO</literal> may appear as
+ separate word on the command line in
+ which case the variable is replaced by
+ its value split at whitespaces. Note
+ that the first argument (i.e. the
+ binary to execute) may not be a
+ variable, and must be a literal and
+ absolute path name.</para></listitem>