use warnings;
use strict;

my @files = <Test*_Copy>;
for my $modfile (@files) {
	open my $fh, '+<', $modfile or die "$modfile: $!";
	my $data = do { local $/; <$fh> };
	$data =~ s/Marry Had A\nLittle Lamb\nShe Was GOOD\n/CHANGED!!!\n/smg;
	seek $fh, 0, 0 or die $!;
	truncate $fh, 0 or die $!;
	print $fh $data;
	close $fh;
}