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Re: Newbie question on serial ports in Linux - please help!

>>>>> "Mikael" == Mikael Bendtsen <Mikael.Bendtsen@eu.pnu.com> writes:

    Mikael>      And by which device should I call my modem which is
    Mikael> connected to the second serial port? /dev/cua1 or
    Mikael> /dev/ttyS1? Where can I find out more about this?
The Linux guru community seems to be divided on this question.  I had
always read that the cua devnames are for _dialout_ connections, and
the ttyS devices are for _dialin_ connections (or was it the other way

But recently I installed mgetty+sendfax (useful if you want to receive
faxes, but also need to dial-up capacity on the same line) and while
browsing the docs, came upon the following tidbit:

   "Some guys seemingly can't resist posting misinformation to the net
all the time, don't believe 'em. The `/dev/cua*' devices are *not*
different from the `/dev/ttyS*' devices concerning data flow or modem
control lines. . . .

   "We use `/dev/ttyS*' all the time for dial-in *and* for dial-out, and
believe me, it works. . . .

   "I'd recommend against using `/dev/modem' as a link to the real
device, but if you do that, make it a *hard link* to the appropriate

After reading this, I switched to an all "ttyS" system -- i.e. I use
the ttyS device everywhere instead of the "cua" or "/dev/modem"
devices, and everything works great.

Nathan L. Cutler
Linux Enthusiast

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