That's right, one second...that may be fine enough. Oh, BTW the disk
is NOT shared. I just need to know if the user that owned the file (and
disk) has changed a particular file (and if so, perform some actions).
Frank M. Ramaekers Jr.
Systems Programmer MCP, MCP+I, MCSE & RHCE
American Income Life Insurance Co. Phone: (254)761-6649
1200 Wooded Acres Dr. Fax: (254)741-5777
Waco, Texas 76710
-----Original Message-----
From: The IBM z/VM Operating System [mailto:ib...@listserv.uark.edu] On
Behalf Of Alan Altmark
Sent: Wednesday, September 09, 2009 5:43 PM
To: IBMVM@LISTSERV.UARK.EDU
Subject: Re: How to tell if a file has been modified
On Wednesday, 09/09/2009 at 04:57 EDT, "Frank M. Ramaekers"
<framaek...@ailife.com> wrote:
> I'm writing a preprocess for editing the directory. I need to be able
> to tell if the directory was actually updated. The information from
the
> PIPE STATE is not precise enough (down to the minute). I can CRC the
> entire file before and after, but this seems a bit much.
Oh, dear. :-) There are few missing elements in your solution.
To know if a file has changed you must have linked MR to the disk. Your
virtual machine has the One True file image and timestamp (which has
resolution of 1 second, btw). If you try to run a CRC on a file of a
disk
that some other virtual machine can write on, you cannot trust what you
read. The directory is, by definition, stale the moment you ACCESS the
disk, and any data blocks pointed to by your possibly-bogus directory
may
have been overwritten. Bleh.
Note that I am excluding the possibility that you would ever link MW to
another CMS guest's minidisks. (shudder)
Alan Altmark
z/VM Development
IBM Endicott
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