>
</div>
<div class="olist arabic">
<ol class="arabic">
<li>
<p>If a system call failed, errno is set and -1 is returned. A diagnostic
is printed.</p>
</li>
<li>
<p>If the program was not found, then -1 is returned and errno is set to
ENOENT; a diagnostic is printed only if .silent_exec_failure is 0.</p>
</li>
<li>
<p>Otherwise, the program is run. If it terminates regularly, its exit
code is returned. No diagnostic is printed, even if the exit code is
non-zero.</p>
</li>
<li>
<p>If the program terminated d