Some operating systems provide two separate devices for each serial
line, one of which is intended especially for gettys. This is
NOT a good idea, because it won’t work with
mgetty. It is
meant for modems used in auto-answer mode.
mgetty picks up the phone by hand, this will only work properly
if you use the same device you would use for dialing out. (Some
people like to create a symlink /dev/modem for this, but you
have to be consistent and use this for all comm programs if you
do - otherwise you’ll run into problems with the lock file names).
Here are some examples for different systems:
ttyF01 etc., (minor number 80+(port number). Do not
ttyFMxxx—mgetty will open the device anyway, but then an
open to the “normal” port (without carrier detect) will block.
Use the modem-control port (
hardware flow control and carrier detection do not work on “lowercase”
The same holds for “smart” serial boards, as specialix, digiboard, …, because they mimic the behaviour of SCO’s sio driver.
Use /dev/ttyS*, not /dev/cua*. See Linux.
Use /dev/cua*, not /dev/ttyS*. Don’t ask me why it has to be
this way, but the other way won’t work. (On SunOS or Solaris, you can
find some gory details in the
man zs man page).