PHP safe mode is off. I even tried turning it on and off again, no change. I set open_basedir = /usr/bin, still no change.
Perl has read and execute permissions. I've searched the php.ini for clues but can't find anything.
This test script shows the results of the "file_exists" function (for /usr/bin/perl) and "perl -v": http://64.6.231.16/test.php
Server is Apache 2.0 with PHP 5.1.6. phpinfo shows 18 additional .ini files parsed besides php.ini. Those are part of a default configuration and I have not looked at all of them, only php.ini.
I have been working on this for weeks, I'm out of ideas, and nearly losing my mind. Can anyone suggest *any* setting to check or any experiment to try?


