/etc/ttydefs is an administrative file that contains records divided into fields by colons (":"). This information used by ttymon to set up the speed and terminal settings for a TTY port.
The ttydefs file contains the following fields:
The string ttymon tries to match against the TTY port's ttylabel field in the port monitor administrative file. It often describes the speed at which the terminal is supposed to run, for example, 1200.
Contains the initial termio (7I) settings to which the terminal is to be set. For example, the system administrator will be able to specify what the default erase and kill characters will be. initial-flags must be specified in the syntax recognized by the stty command.
final-flags must be specified in the same format as initial-flags. ttymon sets these final settings after a connection request has been made and immediately prior to invoking a port's service.
If the autobaud field contains the character 'A,' autobaud will be enabled. Otherwise, autobaud will be disabled. ttymon determines what line speed to set the TTY port to by analyzing the carriage returns entered. If autobaud has been disabled, the hunt sequence is used for baud rate determination.
If the user indicates that the current terminal setting is not appropriate by sending a BREAK, ttymon searchs for a ttydefs entry whose ttylabel field matches the nextlabel field. If a match is found, ttymon uses that field as its ttylabel field. A series of speeds is often linked together in this way into a closed set called a hunt sequence. For example, 4800 may be linked to 1200, which in turn is linked to 2400, which is finally linked to 4800.