c:\@Work\Perl\monks>perl -wMstrict -le
"my $s = qq{aa \n bb \n cc};
 ;;
 print qq{A: match, \$1 '$1' @ $-[1]  \$2 '$2' @ $-[2]  \$3 '$3' @ $-[3]}
   if $s =~ m{
     \A ((?-s: .+)) .+ ((?-s: .+)) .+ ((?-s: .+)) \z
     }xms;
 ;;
 print qq{B: match, \$1 '$1' @ $-[1]}
   if $s =~ m{
     \A ((?-s: .+)) \z
     }xms;
 ;;
 print qq{C: match, \$1 '$1' @ $-[1]}
   if $s =~ m{
     \A ((?-s: (?s: .+))) \z
     }xms;
"
A: match, $1 'aa ' @ 0  $2 ' ' @ 9  $3 'c' @ 11
C: match, $1 'aa
 bb
 cc' @ 0

##</code><code>##

c:\@Work\Perl\monks>perl -wMstrict -le
"my $s = qq{aa \n bb \n cc};
 ;;
 print qq{A: match, \$1 '$1' @ $-[1]  \$2 '$2' @ $-[2]  \$3 '$3' @ $-[3]}
   if $s =~ m{
     \A ([^\n]+) .+ ([^\n]+) .+ ([^\n]+) \z
     }xms;
"
A: match, $1 'aa ' @ 0  $2 ' ' @ 9  $3 'c' @ 11

##</code><code>##

c:\@Work\Perl\monks>perl -wMstrict -le
"my $s = qq{aa \n bb \n cc};
 ;;
 print qq{A: match, \$1 '$1' @ $-[1]  \$2 '$2' @ $-[2]  \$3 '$3' @ $-[3]}
   if $s =~ m{
     \A (?-s) (.+) (?s) .+ (?-s) (.+) (?s) .+ (?-s) (.+) \z
     }xms;
"
A: match, $1 'aa ' @ 0  $2 ' ' @ 9  $3 'c' @ 11