[SA-exim] Config question

[Magnus Holmgren]

On lördagen den 12 september 2009, Brian Lavender wrote:
> This is the sample config and comments on my system. What exactly does the
> {::1} mean?
>
> Is this some sort of LISP or M4 syntax? Sorry, I am not too familiar
> with LISP yet.

It's (part of the) Exim string expansion syntax. See http://www.exim.org/exim-
html-current/doc/html/spec_html/ch11.html. The language is functional, like 
Lisp, but that's where the similarities end. What you have below is an ${if } 
item with a composite condition ("and { }"). The "and" condition takes any 
number of subconditions, each enclosed in braces. The "eq" condition takes two 
operands, also enclosed in braces, whereas the "def" condition takes just one 
after a colon but with no braces. So {::1} is just an IPv6 address enclosed in 
braces to separate it from the other operand, $sender_host_address.

> SAEximRunCond: ${if and {{def:sender_host_address} {!eq
> {$sender_host_address}{127.0.0.1}} {!eq {$sender_host_address}{::1}}}}

-- 
Magnus Holmgren        holmgren at lysator.liu.se
                       (No Cc of list mail needed, thanks)

  "Exim is better at being younger, whereas sendmail is better for 
   Scrabble (50 point bonus for clearing your rack)" -- Dave Evans
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