utmp_update —
update utmpx database
utmp_update is a helper program to allow a user to
  update his own utmpx(5) entry.
  utmp_update does some consistency checks on the
  strvis(3)-encoded
  utmpx_entry and then updates the
  utmpx(5) database of currently
  logged in users.
utmp_update should not be called directly,
    but will normally only be called by
    pututxline(3) if the
    privileges of the calling user are not sufficient.
utmp_update returns 0 on success, and 1 if an error
  occurred.
A utmp_update utility appeared in
  NetBSD 2.0.