Here is some simple code to do it. Put it in a file and redirect the output to list.txt (e.g. foo.pl>list.txt). 
use strict;
my @arr = <STDIN>;
map chomp $_, @arr;
foreach my $i (0..$#arr){
    foreach my $j (0..$#arr){
        print "$arr[$i] $arr[$j]\n" if $i != $j;
    }
}

[download]
Smaller versions surely exist...

Update: If you want to read from list.txt use

foo.pl<list.txt

In reply to Re: help writing simple perl script by traveler
in thread help writing simple perl script by ashylarry

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