L, <code>start_command</code> will point it at the .args
<code>argv_array</code> (so you may use one or the other, but you must use exactly
one). The memory in .args will be cleaned up automatically during
<code>finish_command</code> (or during <code>start_command</code> when it is unsuccessful).</p>
</div>
<div class="paragraph">
<p>The members .in, .out, .err are used to redirect stdin, stdout,
stderr as follows:</p>
</div>
<div class="olist arabic">
<ol class="arabic">
<li>
<p>Specify 0 to request no spe