having terminated the input to the script on stdin, perl cannot read anything more.

Sorry, wrong answer.

Quoting from perldoc perlop:

The <> symbol will return "undef" for end-of-file only once. If you call it again after this, it will assume you are processing another @ARGV list, and if you haven't set @ARGV, will read input from STDIN.

You can give it an end-of-file as many times as you want. If you keep going back and using <> afterwards, it'll read from stdin again. But don't take my word for it; just give it a whirl...

perl -e 'while(1){ print for <> }'
[download]

Type a few lines, ^D, wash, rinse, repeat.

-sauoq
"My two cents aren't worth a dime.";