any ideas anyone?

What my one-liner above demonstrated was that if you read the file with the diamond operator, the way you detect eof, is when it returns undef. If you simply ignore the undefs and continue reading, the eof condition clears itself without any further action required..

Given the docs you cite, I'm not sure if this is "working as designed" or an an undocumented and therefore unreliable feature, but it has worked this way in every version of perl I've used. About the oldest script I have that I still use makes use of this feature.