When arguments are sent to Perl, they're in the @ARGV array. When you read from <>, Perl treats the elements in @ARGV as though they were actually filenames.

Perhaps you want to force a read from STDIN, or else remove the elements from @ARGV (locally, perhaps).

while (<STDIN>) { ... }

# or

{
  local @ARGV;
  while (<>) { ... }
}
[download]

japhy -- Perl and Regex Hacker