n .env_array 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>To specify a new initial working directory for the sub-process,
specify it in the .dir member.</p>
</div>
<div class="paragraph">
<p>If the program cannot be found, the functions return -1 and set
errno to ENOENT. Normally, an error message is printed, but if
.silent_exec_failure is set to 1, no message is printed for this
spec