#!/usr/bin/perl -w
use strict;
use Data::Dumper qw(Dumper);

my (@nulogins, @logins);
my %foo=();
my $fn = 'logins.txt';

open(my $fh, '<', $fn) or die "Could not open file '$fn' $!";
while (my $line = <$fh> ) {
    chomp($line);
    my @login = split /,/,$line;
    push @nulogins, @login;
    #print Dumper \@login;
}
print Dumper \@nulogins;

for (@nulogins) { $foo{$_}++ };
@logins = (keys %foo);

print Dumper \@logins;

exit;