Michael Fowler wrote:
> On Mon, Sep 02, 2002 at 03:56:22PM +0530, Ramprasad A Padmanabhan wrote:
>
>>Hi All,
>> I am writing an web application where multiple users may write into
>>the same file concurrently. Also there is a probability that there may
>>be an admin who has opened up the file in 'vi' and editing the file.
>>
>> I want to avoid this concurrent multiple opens.
>>I tried a range on perl modules like IO::LockedFile, File::Flock;
>>LockFile::Simple etc but all these do not enforce any lock and worst
>>they lock a file even if it is already open in vi
>
>
> As has been mentioned elsewhere on this thread, all of these modules provide
> only advisory locking. This means that each process that wishes to modify
> the file must first lock it with the same method.
>
> This will not cause a problem with your application, because you can add the
> locked ability to it. It will, however, cause a problem with your admin
> editing the file directly. One solution is to force the admin to run their
> editor in a wrapper. For example, you can provide the admin with a simple
> script, say "edit-db-file", that locks the file just as your web application
> does, and then invokes his preferred editor (in $ENV{VISUAL} or
> $ENV{EDITOR}). You'll have to educate your admin (assuming he or she needs
> it) that this is the only method with which they are to edit the file, and
> that they must make their edits quickly. The quickly part is so that the
> web application, and by extension the user of that application, doesn't have
> to wait forever to edit the file, or receive an error after the lock times
> out.
>
> Really, though, why is the admin editing this file directly? Can you not
> provide some sort of web interface for the admin as well? That way the
> admin can't screw up with the lock, and errors in the file itself are less
> likely.
>
>
> Michael
> --
> Administrator www.shoebox.net
> Programmer, System Administrator www.gallanttech.com
> --
Thanx All
But I will still like to have kernel enforced mandatory locking on
the file Can you tell me how to do it
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