Lightweight Databases

`lastlog`

Unix lastlog records are stored in this way

        sub get_lastlog_info {
          my $user = shift;
          $user = getpwnam($user) if $user =~ /\D/;
          return unless defined $user;
          open L, "<", "/var/log/lastlog" or return;
          seek L, 292 * $user, SEEK_SET;
          return unless read(L, my($buf), 292) == 292;
          my ($time, $tty, $host) = unpack "i a32 a256", $buf;
          return ($time, $tty, $host);
        }

To use:

        if (my ($time, $tty, $host) = get_lastlog_info(shift)) {
          print "$user on $tty from $host\n\tat ", 
                scalar(localtime $time), "\n";
        } else {
          print "$user never logged in\n";
        }

        % perl lastlog.pl hkang
        hkang on pts/18 from evrtwa1-ar10-4-61-239-206.evrtwa1.dsl-verizon.net
                at Sat Apr 19 15:45:56 2003

        % perl lastlog.pl www
        www never logged in

Complete code in lastlog.pl