I'm still in a testing phase and I'm not using cron yet. I'm running programa.pl from the command line, and in programa.pl and programb.pl I do check for the existence of the file to attach before continuing. Both those file existence checks pass.

Besides, when I run programa.pl at the command line, I'm a logged in user 'chuck', so the owner of the created XLS file is also 'chuck'. So permissions should not be an issue.

Anyway the file permissions on the XLS file created by programb.pl is: -rw-rw-rw-.