#!/usr/bin/env perl

use strict;
use warnings;

my (@data, @max);

while (<DATA>) {
    push @data => [ split /,/ ];

    @max = map { 
        my $len = length $data[$#data][$_];
        ( $max[$_] ||= 0 ) >= $len ? $max[$_] : $len;
    } 0 .. $#{$data[$#data]} - 1;
}

my $template = 'A' . join(A => ( map { $_ + 1 } @max ), '*');
print pack $template => @$_ for @data;

__DATA__
Account,Login Name,Password,Web Site,Comments,Extra
Google Docs,george123,F0oB@r,http://www.google.com/docs,The GoodleDocs site,A
Amazon,george123,fo0bA7,http://www.amazon.com,The Amazone Kindle site,B
Apple,george123,mM_B39Aa,https://www. ... shorter,My Apple account,C
Longer Account,Login Name,Password,Web Site,Comments,D
Account,Longer Login Name,Password,Web Site,Comments,E
Account,Login Name,Longer Password,Web Site,Comments,F
Account,Login Name,Password,Longer Web Site,Comments,G
Account,Login Name,Password,Web Site,Longer Comments,H
XAccount,XLogin Name,XPassword,XWeb Site,XComments,I