Xref: utzoo comp.unix.questions:28204 comp.unix.internals:1862
Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!bria!mike
Newsgroups: comp.unix.questions,comp.unix.internals
Subject: Re: how to determine if a process has access to tty ports
Message-ID: <385@bria>
Date: 23 Jan 91 09:50:26 GMT
References: <6763@fs1.cam.nist.gov>
Reply-To: bria!mike (Michael Stefanik)
Followup-To: comp.unix.questions
Organization: Briareus Corporation, Los Angeles, CA
Lines: 20

In article <6763@fs1.cam.nist.gov> cam.nist.gov!coleman (Sean Sheridan Coleman X5672) writes:
:I want to be able to determine if another process has control
:of an RS232 port on a Alm Board on a Sun4. I am writing a 
:program to gather data from a device that is connected via
:RS-232. I want to deny access to the program if another program
:is accessing the port currently. 

If you're worried about login processes, you could read /etc/utmp (but if
this is a special device, I doubt that's the case); the slicker solution
would be to read the namelist in /unix, and look through the proc table.
A similar (but considerably slower) solution would be to popen() ps -t ttyxx
and see if there is anything attached to it.  If you're looking for any
process that has simply done an open() on the port, though, that's another
story.
-- 
Michael Stefanik, Systems Engineer (JOAT), Briareus Corporation
UUCP: ...!uunet!bria!mike
--
technoignorami (tek'no-ig'no-ram`i) a group of individuals that are constantly
found to be saying things like "Well, it works on my DOS machine ..."