[0] Perl> print "$_ : ", /(?=^.*fred)(?=^.*bill)/ 
    ? 'matched' 
    :'no match' 
    for qw[ fred&bill bill&fred bill&john fred&john john&bill john&fred sucker! ];;
fred&bill :  matched
bill&fred :  matched
bill&john :  no match
fred&john :  no match
john&bill :  no match
john&fred :  no match
sucker! :  no match
[0] Perl>