This implements the C library function of the same name, which on most systems returns the current login from /etc/utmp, if any. If it returns the empty string, use getpwuid.
$login = getlogin || getpwuid($<) || "Kilroy";Do not consider getlogin for authentication: it is not as secure as getpwuid.
Portability issues: "getlogin" in perlport.