Port Initialization Process

When an instance of ttymon is invoked by SAC, ttymon starts to monitor its ports. For each port, ttymon first initializes the line disciplines, if they are specified, and the speed and terminal settings. The values used for initialization are taken from the appropriate entry in /etc/ttydefs.

The ttymon port monitor then writes the prompt and waits for user input. If the user indicates that the speed is inappropriate by pressing the Break key, ttymon tries the next speed and writes the prompt again.

If autobaud is enabled for a port, ttymon will try to determine the baud rate on the port automatically. Users must press Return before ttymon can recognize the baud rate and print the prompt.

When valid input is received, ttymon interprets the per-service configuration file for the port, creates a /etc/utmp entry if required, establishes the service environment, and invokes the service associated with the port.

After the service terminates, ttymon cleans up the /etc/utmp entry, if one exists, and returns the port to its initial state.