Example 8-9. laston

  #!/usr/bin/perl -w
  # laston - find out when given user last logged on
  use User::pwent;
  use IO::Seekable qw(SEEK_SET);
  
  open (LASTLOG, "< :raw", "/var/log/lastlog")
      or die "can't open /var/log/lastlog: $!";
  
  $typedef = "L A12 A16";  # linux fmt; sunos is "L A8 A16"
  $sizeof  = length(pack($typedef, ( )));
  
  for $user (@ARGV) {
      $U = ($user =~ /^\d+$/) ? getpwuid($user) : getpwnam($user);
      unless ($U) { warn "no such uid $user\n"; next; }
      seek(LASTLOG, $U->uid * $sizeof, SEEK_SET) or die "seek failed: $!";
      read(LASTLOG, $buffer, $sizeof) =  = $sizeof        or next;
      ($time, $line, $host) = unpack($typedef, $buffer);
      printf "%-8s UID %5d %s%s%s\n", $U->name, $U->uid,
            $time ? ("at " . localtime($time)) : "never logged in",
            $line && " on $line", 
            $host && " from $host";
  
  
  
  }