my $inp = <<'END';
<%= my $capi = 'foo'; $capi; %>
<%= my $marega = 'bar'; $marega; %>
END
while($inp =~ /<%=(.*?)%>/s) {
	print "Dollar 1 before eval = $1\n";
	$inp =~ s/<%=(.*?)%>/eval $1/es;
	print "INP after substitution = $inp\n";
}

__END__

Dollar 1 before eval =  my $capi = 'foo'; $capi; 
INP after substitution = foo
<%= my $marega = 'bar'; $marega; %>

Dollar 1 before eval =  my $marega = 'bar'; $marega; 
INP after substitution = foo
bar