perl> $" = ''


 perl> $s = ((qq(@{[0..8]}) x 4).$/)x4

 perl> print $s
012345678012345678012345678012345678
012345678012345678012345678012345678
012345678012345678012345678012345678
012345678012345678012345678012345678

 perl> print 'Matched'.$/ if ( $s =~ m/(.{40}\n){4}/ )


 perl> $s = ((qq(@{[0..9]}) x 4).$/)x4

 perl> print $s
0123456789012345678901234567890123456789
0123456789012345678901234567890123456789
0123456789012345678901234567890123456789
0123456789012345678901234567890123456789

 perl> print 'Matched'.$/ if ( $s =~ m/(.{40}\n){4}/ )
Matched

 perl>