# nasty.pl

use strict;
use warnings;

$| = 1;

print 'first line: ', scalar <>;

while (<>) {
  print "first loop: $_";
}

while (<STDIN>) {
  print "second loop: $_";
}

__END__

##</code><code>##

% echo 'just another one-line file' > one-line_file
% yes junk | head -3 | perl nasty.pl one-line_file
first line: just another one-line file
second loop: junk
second loop: junk
second loop: junk