[det]openlog(+Ident:atom, 
+Options:list(atom), +Facility:atom)openlog() 
library call. If the library call is successful, it runs at_halt(closelog) 
to ensure closing the system log on clean exit.
| Ident | prepended to every message, and is typically set to the program name. | 
| Options | is a list of options. Values are 
corresponding C options, after removing =LOG_= and translation to lower 
case: cons, ndelay, nowait, odelay,
perror, pid.  | 
| Facility | is one of auth, authpriv, cron, daemon,
ftp, kern, local0 ... local7, lpr, mail,
news, syslog, user or uucp.  |