DB<105> $cond = q($field[6] eq 'PM' && $field[8] eq 'CAVENDI');
 => "\$field[6] eq 'PM' && \$field[8] eq 'CAVENDI'"

  DB<106> @field = ()

  DB<107> $ret =eval $cond
 => ""

  DB<108> @field = (0,0,0,0,0,0,'PM',0,'CAVENDI')
 => (0, 0, 0, 0, 0, 0, "PM", 0, "CAVENDI")

  DB<109> $ret =eval $cond
 => 1

##</code><code>##

~$ perl 
$cond="bla eqx 2"; 
eval { $ret =eval $cond } or warn "Problem with $cond";
__END__
Problem with bla eqx 2 at - line 2.