CHAPTER 17 Service Access Facility
The Service Access Controller (sac) is the master SAF process. It's spawned by init at run level 2 and controls the port monitors. It can add or remove and start or stop the port monitors. The port monitors control either a serial or network port. They connect incoming requests to services, which are arbitrary processes, such as login. The port monitor administrative commands can add or delete and start or stop services for the ports.
The getty process is no longer used. It was considered too inflexible in that the only service it provided was login. Also, it didn't scale well to large numbers of ports, as you had to run a getty process for every port it monitored.
The SAC administers the port monitors with the sacadm command. Each port monitor can control one or many ports. The ports are administered through the pmadm command. The pmadm command controls the services provided by ttymon and listen. One ttymon daemon serves multiple serial ports and one listen daemon provides multiple services to the network ports.
Serial ports can be configured using the Serial Port Manager facility of the admintool GUI described in a later chapter, or by using the commands specified below.