in reply to How regex works here?

have a look :-)
use strict; use warnings; use re qw(debugcolor); my $lines = 'B6y green $1$Byf3501d$dPtaW2vCbq63sdsw'; $lines =~ s/^(\S+\s\S+)/$1/; print "$lines";

print+qq(\L@{[ref\&@]}@{['@'x7^'!#2/"!4']});