$!  aka $ERRNO      
            If used in a numeric context, yields 
            the current value of errno, with all
            the usual caveats.  
$?  aka $CHILD_ERROR
             The status returned by the last pipe 
             close,  backtick(``) command, or 
             system() operator. 
$@  aka $EVAL_ERROR
             The Perl syntax error message from the 
             last eval() command