Re: [EXIM] Locking a pipe

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Author: Jeffrey Goldberg
Date:  
To: Philip Hazel
CC: exim-users
Subject: Re: [EXIM] Locking a pipe
On Fri, 24 Jul 1998, Philip Hazel wrote:

> On Fri, 24 Jul 1998, Jeffrey Goldberg wrote:
>
> > I expect that the answer is no, but I will ask anyway.
> >
> > Is there an easy way to lock a pipe transport so that any new message to
> > be delivered to the pipe will be deferred if there is an uncompleted
> > delivery on the pipe?
>
> I'm afraid the answer is indeed no.


As I suspected.

> Indeed, I cannot conceive of what "locking a pipe" might actually mean.


It is a bit of an incoherent question, but I thought that I had made my
actual intention clear.

> > The idea is so that we can write a program to process some messages
> > without having to worry about locking ourselves.
>
> Surely processing multiple messages in parallel is not a problem per se?


True ...

> But I suspect you are going to write things to files, and that is where
> the problem lies.


Exactly. Data from the mail piped to the command will be written to a
file, and if I could avoid having to code locking into a what might
otherwise be a very simple script, I would be pleased.

> I do have lying around a testing program that locks files using the same
> code as Exim does. I suppose I could tart it up into some kind of
> utility one of these days so one could run commands like
>
> eximlock /some/file "/and/run/this/command while locked"


IT would be nice if something like that were readily available. Somehow,
I suspect that must already be out there, somewhere.

-j

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Jeffrey Goldberg                +44 (0)1234 750 111 x 2826
 Cranfield Computer Centre      FAX         751 814
 J.Goldberg@???     http://WWW.Cranfield.ac.uk/public/cc/cc047/
Relativism is the triumph of authority over truth, convention over justice.



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