getlogin - get login name
Getlogin returns a pointer to the login name as found in /etc/utmp.
It may be used in conjunction with getpwnam to locate the correct
password file entry when the same userid is shared by several login
If getlogin is called within a
process that is not attached to a
terminal, or if there is no entry in /etc/utmp for the process’s
terminal, getlogin returns a NULL pointer (0). A reasonable
procedure for determining the login name is to first call getlogin
and if it fails, to call getpwuid(getuid()).
getpwent(3), utmp(5), ttyslot(3)
Returns a NULL pointer (0) if name not found.
The return values point to static data whose content is overwritten
by each call.