use warnings;
use strict;

my @files = <Test*_Copy>;
for my $modfile (@files) {
	# read
	open my $ifh, '<', $modfile or die "$modfile: $!";
	my $data = do { local $/; <$ifh> }; # slurp
	close $ifh;
	# modify
	$data =~ s/Marry Had A\nLittle Lamb\nShe Was GOOD\n/CHANGED!!!\n/smg;
	# write
	open my $ofh, '>', $modfile or die "$modfile: $!";
	print $ofh $data;
	close $ofh;
}