pty bugs & features

[Guy Harris]

>Most printers will supply a ^Q when powered up, when the lid is closed,
>when the on-line button is pressed, etc.   I'd prefer for the computer
>to wait for such an occurrance rather than trying to guess when the
>paper supply has been replenished.

I'd prefer that too; I was bit by the S3 tty driver's insistance on
turning off flow control and sending any buffered-up data when the tty
line was closed.  I'm just asking how a session manager would help in
the case where a ^Q sent by the printer in the circumstances you list
gets lost in transit. 

>The real problem is when you have placed a long distance call to or from
>a modem on a unix machine and pick up a ^S from line noise.  I've even
>seen cases where the device driver would lock up so that even a kill -9
>wouldn't release the process and there was no way to drop the call without
>physical access to the modem.

If the call is still active, presumably typing ^Q would unlock the line,
unless there's a driver bug.  Hanging the phone up should unlock the
line too, unless there's a driver bug....