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Re: /dev/cu.* vs /dev/tty.* ?
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Re: /dev/cu.* vs /dev/tty.* ?

On Jun 15, 2006, at 12:26 , Andre-John Mas wrote:


I am using the Java Communications API, implemented at and whe I call the API it lists both the /dev/cu and /dev/tty devices. I am not sure that both need to be listed, especially if this is presented to the user. Some people feel both should be listed, others like myself don't think so.

I hoping someone who is more familiar with the inner workings can tell me what the difference is between the two, and more specifically which one a serial communication tool should use.

Typically, the tty* and cu* are different versions of the same "physical" thing: the tty's are for incoming (to the system) calls; the cu's are for outgoing (from the system) calls ("cu" == "call unix"; don't ask :-}). You can match them with their major/minor pairs, noting that the cu devices have odd minors, while the tty devices have even minors ('OR'ing a low-order bits gets you the "cu" for a corresponding "tty").

I don't know that this helps you much :-}



Justin C. Walker, Curmudgeon-At-Large
Institute for the Absorption of Federal Funds
Some people have a mental horizon of radius zero, and
call it their point of view.
  -- David Hilbert

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 >/dev/cu.* vs /dev/tty.* ? (From: Andre-John Mas <email@hidden>)

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