The oldest Perl code written by me I could find was located in my university account (yes, I still have access there, as I occasionally help them with projects I was once involved in). It's called array2.pl (I wonder what happened to version 1), it's modification time is the 12th November 2001 and it looks like this:

#!/usr/bin/perl -w
#

use integer;
sub swap
{
    $_[0]=$_[0] ^ $_[1];
    $_[1]=$_[0] ^ $_[1];
    $_[0]=$_[0] ^ $_[1];    
}
sub nsd
{
    my ($a,$b)=@_;
    do 
    {
    if ($a<$b) {$b-=$a}
    elsif ($b<$a) {$a-=$b}
    } until ($a==$b);
    return($a)
}
# main
print ("Array size: ");
chomp($n=<stdin>);
print ("Shift: ");
chomp($d=<stdin>);
print("NSD:",nsd($n,$d),"\n");
for ($i=0;$i++<$n;$array[$i]=$i){}
#
for ($j=0;$j<nsd($n,$d);$j++)
{
    $i=$n-$j;
    $aux=$array[$i];
    unless ($next=($i+$d)%$n) {$next=$n}
    do {
    for($k=0;$k++<$n;printf("%2.0d",$array[$k]),print(",")){}
    print("\n");
    $array[$i]=$array[$next];
    $array[$next]=$aux;
    $i=$next;
    $aux=$array[$i];
    unless ($next=($i+$d)%$n) {$next=$n}
    } until ($next==$n-$j);
}
for($k=0;$k++<$n;print($array[$k],",")){}
[download]

I was probably experimenting with the programming language that was new to me. For some reason, I disliked whitespace. Is this some kind of self-embarassment contest? ;-)