use warnings;
use strict;
my $file = 'C:/tmp/filename1.txt';

open IN, $file or die "Cannot open $file for reading:$!\n";
print "Contents of $file before linking:\n";
print while (<IN>); 
close IN;

my $link = 'C:/tmp/link.txt';
if (-e $link) { unlink $link or die $!; }

link $file,$link or die "Cannot link $link to $file:$!\n";

open LINK, $link or die $!;
print "Contents of $link after linking:\n";
print while (<LINK>);
close LINK;

open (OUT, ">>", $file) or die "Cannot open $file for writing:$!\n";
print OUT "Additional content\n";
close OUT; 

open IN, $file or die $!;
print "Coontents of $file after updating:\n";
print while (<IN>);
close IN;

open LINK, $link or die "Cannot open $link:$!\n";
print "Contents of $link after updating:\n";
print while (<LINK>);
close LINK;