#  # add double-quote characters to either end of realname
#  # $realname = '"' . $realname . '"';

  # commented out above line after fruiture pointed out that 
  # system LIST format makes it unnecessary -- and even 
  # wrong, since realname would then be stored with '"' 
  # on either side!

  # run system command, but pass args directly to the 
  # adduser program, rather than booting a shell
  if (!system("adduser",
              $username,
              '-g', '100',
              '-s', '/bin/false',
              '-d', "/home/$username",
              '-p', $encrypted_pass,
              '-e' $expiry_date,
              '-c' $realname
              )
     ) {
     die "trouble adding user: returned non-zero\n";
   }