ttydefs(4)

ttydefs -- file contains terminal line settings information for ttymon

Description

/etc/ttydefs is an administrative file that contains information used by ttymon to set up the speed and terminal settings for a TTY port.

The ttydefs file contains sets of flag entries, which indicate input, output, control, and other settings (see stty). These settings are stated in five fields, delimited by colons (:) and flag entries within each field are delimited by spaces, as in the example.

The fields comprising each line of ttydefs include:

ttylabel: Typically, the baud rate for the terminal line, used as a string to conduct a search for an acceptable port. ttymon tries to match this string against the TTY port's ttylabel field in the port monitor administrative file. ttylabel usually describes the speed at which the terminal is supposed to run, for example, 1200. Speeds of up to 115200 baud may be specified.
initial-flags: The termio settings to be applied during the initial phase of login to set and/or unset the modes to be used on that line. See the Usage Section below for the original settings referenced by initial-flags. initial-flags settings may be used by the system administrator, for example, to specify what the default erase and kill characters will be. initial-flags must be specified in the syntax recognized by the stty command. Settings to be turned on have no prefix or are preceded by a plus sign (+); settings to be turned off are preceded by a minus sign (-).
final-flags: The termio settings used for final-flags are applied over the initial-flags settings. This is done by ttymon after a connection request has been accepted and immediately prior to invoking a port's service. final-flags must be specified in the same format as initial-flags, that is, in the syntax recognized by stty.
autobaud: If this field contains the character `A', autobaud will be enabled. Otherwise (if the field is blank), autobaud is not enabled. ttymon determines what line speed to set the TTY port to by analyzing the carriage returns entered. The hunt sequence indicated in ttydefs with the nextlabel entry is used for baud rate determination unless autobaud is enabled.
nextlabel: If the user indicates that the current terminal setting is not appropriate by sending a BREAK, ttymon searches 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.

Usage

The settings provided via ttydefs allow for management of terminal settings through the various phases of service start-up.

Original settings

The initial-flags settings are applied to the following original values:

Input Modes: ignpar istrip icrnl ixon
Control Modes: cs7 cread parenb b9600
Output Modes: opost onclr
Local Modes: isig icanon echo echoe echok

Default settings

If you use sane to indicate that the ttymon settings in the port monitor administrative file be used, the following settings will serve as the values for initial-flags.

Control Modes: cs7 parenb cread -parodd -clocal
Input Modes: brkin tignpar istrip icrnl ixon -ignbrk -parmrk -inpck -inlcr -igncr -iuclc -ixoff
Local Modes: isig icanon echo echoe -xcase -echoe -echonl -noflsh -stflush stwrap -stappl
Output Modes: opost onlcr -olcuc -ocrnl -onocr -onlret -ofill -ofdel -ndly -crdly -tabdly -bsdly -vtdly -ffdly

Specific values may be restated following the use of sane, as in the example, to modify these defaults.

References

stty(1), sttydefs(1M), termio(7), ttymon(1M)

Examples

The following is an example of a no-parity 9600-baud entry.

   9600np:9600 ignbrk -parenb:9600 sane ixany tab3 hupcl erase ^h::4800

ttylabel: 9600np
initial-flags: 9600 ignbrk -parenb
final-flags: 9600 sane ixany tab3 hupcl erase ^h
autobaud: no
nextlabel: 4800

The example calls for initial-flags to be applied to the original settings stated above. As a result, the following flags will be in effect for the initial phase:

Input Modes: ignpar istrip icrnl ixon ignbrk
Control Modes: cs7 cread b9600
Output Modes: opost onclr
Local Modes: isig icanon echo echoe echok

(Note that an Input Mode setting of ignbrk is turned on and a Control Mode setting of parenb is turned off as a result of the initial-flags settings in the example.)

Also in the example, final-flags uses sane. This results in applying the default values for sane, listed above. The settings for final-flags that follow sane (ixany, tab3, and so on) are then applied over the sane defaults.