# I'm stuck here. Don't know how 
     # to construct the command correctly...
     run \@cmd, '<pty<', \$in,  '>pty>', \@output ;

##</code><code>##

     # Redirecting using psuedo-terminals instad of pipes.
     run \@cat, '<pty<', \$in,  '>pty>', \$out_and_err ;