dovecot - Oct 2020 - Sieve body test

I have an email where I need to edit the body. I know this is generally a bad
idea, but in this case I need to do it. The email comes in automatically every
week or two, and so I thought that SIEVE would be the way to go.

if header :contains "from" "theaddress at tehdomain" {
        if body :raw :contains "A string" {
	  # Magic happens here
        }
}

It looks like what I need to do is enable and use vnd.dovecot.filter to pipe the
message to a script. (Er. | not vnd.dovecot.pipe)

So, if I wanted to transform the message so that the string "foobar13"
was changed to "foo-bar-13"

I would add 

       filter :try "myfoobarfix.sh" 

After "magic happens here">

OK so far?

Now, what are the requirements on the executable script? Would it literally be
as simple as an executable file that simply said

sed -e '|foobar13|foo-bar-13|g'

Or does it need to be a shebang script and take input on $1 and ? ? 

And lastly, where do the executable scripts need to be?
https://raw.githubusercontent.com/dovecot/pigeonhole/master/doc/rfc/spec-bosch-sieve-extprograms.txt
says "the external programs cannot be chosen arbitrarily; the available
programs are restricted through administrator configuration", but no
details on exactly how that is configured.


-- 
"Are you pondering what I'm pondering?"
Pinky: I think so, Brain. But if I put on two tutu's, would I really
	be wearing a four-by-four?
Brain: Why do I even bother asking?
Pinky: I dunno, Brain. Maybe it's all part of some huge, cosmic
	plot formula!

On 20 Oct 2020, at 13:46, @lbutlr <kremels at kreme.com>
wrote:
> 
> It looks like what I need to do is enable and use vnd.dovecot.filter
error: require command: unknown Sieve capability `vnd.dovecot.filter'.

Is this not available to a user? I guess I can put the in global, but ick.

-- 
he'd moved like music, like someone dancing to a rhythm inside his
	head. And his face for a moment in the moonlight was the skull of
	an angel...

On 20/10/2020 23:37, @lbutlr wrote:
> On 20 Oct 2020, at 13:46, @lbutlr <kremels at kreme.com> wrote:
>> It looks like what I need to do is enable and use vnd.dovecot.filter
> error: require command: unknown Sieve capability `vnd.dovecot.filter'.
>
> Is this not available to a user? I guess I can put the in global, but ick.
You need to include the extprograms plugin:

https://doc.dovecot.org/configuration_manual/sieve/plugins/extprograms/

The language extension is described here:

https://raw.githubusercontent.com/dovecot/pigeonhole/master/doc/rfc/spec-bosch-sieve-extprograms.txt

Regards,

Stephan.