$arg = shift; # $arg is tainted
$hid = $arg, 'bar'; # $hid is also tainted
$line = <>; # Tainted
+ $line = <STDIN>; # Also tainted
+ open FOO, "/home/me/bar" or die $!;
+ $line = <FOO>; # Still tainted
$path = $ENV{'PATH'}; # Tainted, but see below
$data = 'abc'; # Not tainted