#!/usr/bin/perl -w
open ($FH,'| sort -n') or die($!);
while(<ARGV>){
        print $FH $_;
}
close $FH;

##</code><code>##

[demo@localhost Perl]$ cat bar.pl
#!/usr/bin/perl -w
open (FH,'| sort') or die($!);
$count=0;
while(<ARGV>){
	print FH $_;
	print $count++ . "\n";
}
close FH;

[demo@localhost Perl]$ bar.pl words 
0
1
2
3
4
A
ABC
a to z
Buy
Why