What's the best way to get notified of a user login on Linux?

I'm currently using gentoo and have the following method of knowing when anyone logs into my server (it's really just me, but if anyone were to gain access, I'd want to know about it)

1) Use sec to monitor logfiles

type=SingleWithScript
ptype=RegExp
pattern=Accepted keyboard-interactive/pam for ([a-z]+) from ([0-9|\.]+) port
script=/root/scripts/userLogin.pl $1 $2
desc=User Login
action=write /var/log/sec/sec.log User Login: $1 has logged in from $2
action2=write /var/log/sec/sec.log Script Failed: User Login: $1 has logged in from $2

2) Script:

#!/usr/bin/perl -w
use Net::SMTP::TLS;

my $smtp;
if (not $smtp = Net::SMTP::TLS->new('smtp.gmail.com',
                            Port => 587,
                            User => '',
                            Password => '',
                            Debug => 1)) {
    die "Could not connect to server\n";
}

$smtp->mail('');
$smtp->to('');
$smtp->data();
$smtp->datasend('To: ' . "\n");
$smtp->datasend('From: ' . "\n");
$smtp->datasend("Subject: User Login: $ARGV[0]\n");
$smtp->datasend("\n");
$smtp->datasend("$ARGV[0] has logged in from $ARGV[1]\n");
$smtp->dataend();
$smtp->quit;

But I'm worried that my regex isn't broad enough. "Accepted keyboard-interactive/pam" - can logins generate logs that don't match that format?