Why does getlogin() always return NULL on my Linux box?
{UD} The GNU C library has a format for the UTMP and WTMP file which differs from what your system currently has. It was extended to fulfill the needs of the next years when IPv6 is introduced. The record size is different and some fields have different positions. The files written by functions from the one library cannot be read by functions from the other library. Sorry, but this is what a major release is for. It’s better to have a cut now than having no means to support the new techniques later.
