Ok, so you can show what users have accounts, unfortunately I'm trying to show the exact opposite. Here is what I came up with:

#!/usr/bin/perl

use strict;
use Data::Dumper;

# Grep a user OUT of a file, given a list of names, likely from anothe
+r file

# psuedo code:
# if file1 contains a name from file2, skip the line
# if file1 does NOT contain a name from file2, print the line.
#
# I am using this to determine a list of accounts on the partners serv
+er
# that, *maybe*, shouldn't be on there any more.

my @users;
my %lines;
my $file1=$ARGV[0];
my $file2=$ARGV[1];

open FILE1, "<$file1" or die "Cannot open $file1: $!\n";
  # Hasherize it!!!
  foreach my $line (<FILE1>) {
    chomp($line);
    $lines{$line}=0;
  }
close FILE1;

# Create @users array
open FILE2, "<$file2" or die "Cannot open $file2: $!\n";
foreach my $line (<FILE2>) {
  if ($line =~ /#/) {
    my @out=split /\s+/,$line;
    push @users,$out[1];
  }
}
close FILE2;

foreach my $key (keys(%lines)) {
  foreach my $user (@users) {
    if ($key =~ /$user/i) {
      $lines{$key}++;
    }
  }
}

print "List of users not authorized to have an account\n";
foreach my $key (sort keys(%lines)) {
  if ($lines{$key} <= 0) {
    print "$key\n";
  }
}

print "\nList of users authorized to have an account\n";
foreach my $key (sort keys(%lines)) {
  if ($lines{$key} > 0) {
    print "$key\n";
  }
}
[download]

It handily prints out what should be there, and what should not. Now all I have to do is some manual verification, and I can call this a lesson learned.

Many thanks to all those with quick replies, and mostly to jpl for the hint in the direction of hashes.

wind: You code is excellent, but only prints out those folks authorized to have accounts, how would I modify your code to print the inverse list? I tried negating the match (=~ to !=~), but it failed in a quite spectacular way.

UPDATE:
I added a sort into each foreach loop above to print out the lines in alphabetical order.