ion, parses it and caches it for future use. <code>doGRASS</code> assembles
a proposed GRASS command with flags and parameters as a string, wrapping
<code>parseGRASS</code>, and <code>execGRASS</code> is a wrapper for <code>doGRASS</code>,
running the command through <code>system</code> (from 0.7-4, the <code>...</code>
argument is not used for passing extra arguments for <code>system</code>). The
command string is termed proposed, because not all of the particular needs of
commands are provided by the inte