Operator Action
$foo and $bar TRue if $foo and $bar are TRue
$foo or $bar true if $foo or $bar is true
$foo xor $bar true if and only if $foo or $bar is true (only one or the other)
!$foo true if $foo is not true
$foo && $bar TRue if $foo and $bar are true
$foo || $bar true if $foo or $bar is true