[CLUG] I'm locked!

[Baldwin_James at emc.com]

Cheers Paul for the info..

To explain, (with return comments) see below :)

>>>>> "BJ" == Baldwin James <Baldwin_James at emc.com> writes:

    BJ> How do ya find out the PID's & UID's (and/or maybe parent
    BJ> PID's of Child processes) which are locking a file?

lsof can tell which processes have a file open.  I think it will also
indicate if the file is locked.  Given the PID gleaned from lsof, you
can then use ps to get any other needed information.

    BJ> How could you unlock the file from them without killing their
    BJ> process?

Paul asked: > Why would you want to do that?  If you did do that, the
calling
Paul asked: > process with the lock wouldn't know about it, so it would
carry on
Paul asked: > doing whatever it is doing to the locked region.

If a process is hung which has a log file locked for exclusive access, and
you wanna examine that log file without destroying the PID and then return
the lock back to the PID.  I am basically trying to be as non-intrusive as
possible (this instance would be on a remote system).

    BJ> How could you inform the user or push a std. file-handling
    BJ> command to instruct the process to release the file?

Paul asked: > I'm not sure what you mean by this, to be honest.

Lets say, you are able to identify that Bob the Builder, (e.g. UID#505) has
Frags.log open and you want to use (Read/Write)that file.  You need to
inform Bob to release/close that file so you can get it.  How can you inform
Bob about this?  

If Bob the builder is a process rather than a user, then is it possible for
some type of Unix/Linux directive to basically say "hey, Mr. Bob, I really
want to use that file you have locked.  Please freeup that file and report
accordingly to User/Parent process that you had a request for that file, but
dont try to bomb out..."
(I would think the above request would be app-dependent unless coders follow
some type of practice like this????)


Cheers Paul,
James.



-- 
"Pity has no place at my table."
      -- Dr Hannibal Lecter

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