use strict;
use warnings;


sub main {

	my $input = ('D:\Perl\Paul\My_Text.txt');
	my $output = 'My_Output.txt';
	
	open(INPUT, $input) or die("$input - Not found \n");
	open(OUTPUT, '>'.$output) or die("Can't create $output \n");
	
	while(my $text = <INPUT>){
			 if($text =~ /(\bdog\b)/){
				# The \b above are word boundaries
				# Result is stored in variable $1
				print OUTPUT "$1\n";
				
			 }
		
		}
		
	close(INPUT);
	close(OUTPUT);
	
}
	

main();