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From: it1@Isis.MsState.Edu (Tim Tsai)
Newsgroups: comp.unix.programmer
Subject: Checking if a process opened a file
Message-ID: <it1.670574750@Isis.MsState.Edu>
Date: 2 Apr 91 06:45:50 GMT
Sender: usenet@ra.MsState.Edu
Lines: 27
Nntp-Posting-Host: isis.msstate.edu


  Is it possible to check if a process (possibly from another machine
via NFS) opened a file for reading/writing?  I've mucked with the
select() call, but the call always returns with the value 1.  What is
an "exceptional condition"?  Here's a sketch of what I've attempted
(with error checking, etc removed):

    infile = open ( filename, O_RDONLY );
    FD_ZERO ( &fdset );
    FD_SET ( infile, &fdset );
    for (;;)
    {
        result = select ( ulimit(), 0, 0, &fdset, 0 );
        printf ("exceptional condition on %s, result = %d\n", filename,
            result);
    }

  BTW, I know about named pipes.  I'm interested in regular files.

  This is on a Sun4, SunOS 4.1.1..  Thanks in advance for any help..

  PS:  I also tried poll(), with timeout set to -1 and events set to
  POLLPRI..  Same result.

--
  Never argue with a fool, people might not know the difference.
                                                       <Murphy's Law>