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.