6.4. mgetty
mgetty is a modem-aware
getty. It supports modems with the
Hayes AT command set and is especially designed
for supporting modems that are used to send faxes and to dial out
as well as dial in. These features are not required for a serial
console.
mgetty does not require the
traditional /etc/gettydefs file. As a result
mgetty is invoked from
/etc/inittab without supplying an entry in
/etc/gettydefs.
mgetty is configured using the
file /etc/mgetty+sendfax/mgetty.config. It
should contain an entry for the port used by the serial
console.
All the options are documented in the
PostScript file
/usr/share/doc/mgetty…/mgetty.ps.
We set direct,
data-only, need-dsr and
toggle-dtr so that the RS-232
control lines are used correctly for a dumb modem.
port-owner, port-group
and port-mode set the serial device to be
accessible only by the root user. Modem applications, which
normally use the uucp
group, cannot now accidentally use the serial console.
login-prompt shows the machine
(@) and serial port (\P)
being used. The text \040 is simply the octal
code for a space after login:.
term vt102 gives the make and model of the
terminal most likely to dial in. This sets the
TERM environment variable, which you can change
if you are dialling in from another terminal type.
The remaining configuration files,
/etc/mgetty+sendfax/dialin.config and
/etc/mgetty+sendfax/login.config, do not need
to be altered.
If you wish to alter the suggested configuration then note
that mgetty's
blocking and toggle-dtr
parameters do not co-exist well.
If you have difficulties, activate debugging by adding
debug 8 to mgetty.config.
mgetty's actions are then visible in the
file /var/log/mgetty.log.ttyS0.