Columbia Kermit/kermit.zip/newsgroups/misc.19990725-20000114/[e-mail] _Thu Oct 14 09:25:52 1999.msg

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From: [e-mail] (Frank da Cruz)
Subject: Opening a tty for exclusive access
Date: 14 Oct 1999 13:11:31 GMT
Organization: Columbia University
Message-ID: <7u4kq3$lea$[e-mail]>
To: [e-mail]


An interesting question came recently in the beta testing of
C-Kermit 7.0:

  http://www.columbia.edu/kermit/ck70.html

How does one open a dialout (tty) device in QNX for exclusive
access?  In other forms of UNIX we have the hideous UUCP
lockfile mechanism, but not in QNX.

A user who was testing Kermit on QNX tried out the "find a free
dialout device" script:

  http://www.columbia.edu/kermit/ckscripts.html
  ftp://kermit.columbia.edu/kermit/scripts/ckermit/getline

and it didn't work at all.  User A could grab /dev/ser1, make a
call, and be carrying on a session, and user B could open the
same device while user A's session is active.

I assume that QNX must have some API for opening a device (or
file) for exclusive access, but I don't know what it is.  Can
someone help?

Thanks!

Frank da Cruz
The Kermit Project
Columbia University