That's why I like to avoid invoking a shell either explicitly or implicitly when calling external programs.

Isn't that exactly why system has the list argument form?

Sounds to me like you are asking for perl to restrict everyones access to useful behaviour in order to save you from yourself.

Of course, what really will happen depends on what the strings $one, $two and $three contain.

No shit Sherlock :) And the result of print $a + $b + $c; will depend upon what's in $a, $b & $c.

I once wrote that I considered ...considered harmful., harmful. And nothing I've seen in the intervening 6 years has done anything to change my mind. Most times when someone writes "XXX considered harmful", they are really saying "I just got bitten by XXX" and so I think that Perl/government/other should do something to save me from myself. And this is no exception.