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gucki
Asked: 2012-12-20 09:27:34 +0800 CST

exim, variable string expansion

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How can I get the list of local domains from a forward file?

An example of /etc/exim4/forwards:

[email protected]: [email protected]
# ignore this line
[email protected]: [email protected]
[email protected]: [email protected]

Here the string expansion (or what ever it's called g) should return test.com : hugo.com.

I assume it can be done with readfile and map, but I can't get it to work.

exim

1 Answers

  1. I have something that almost works the way you want it. What this expansion does is:

    1. Slurp in the file, using ; as the separator.
    2. Exclude any lines with # in them (i.e. comments).
    3. It should skip blank lines, but my regex isn't matching, it still includes those blank lines, so I just removed it and left the or{{}{}} block in there.
    4. Extract the item before the : on each line, and extract the domain from that.
    5. Mash it all up into the list.

    I don't profess this to be exactly what you need, but it shows how the lists can be parsed and grep'd.

    CentOS58[root@ivwm41 exim]# more test_list.cf 
[email protected]: [email protected]
# ignore this line
[email protected]: [email protected]
[email protected]: [email protected]

CentOS58[root@ivwm41 exim]# exim -be '${reduce {<; ${readfile{/etc/exim/test_list.cf}{;}} } {} {${if  or{ {match{$item}{#}} {match{$item}{#}} } {$value} {$value:${sg {${extract{1}{:}{$item}}} {^.*@}{} }}}}}'
:test.com:test.com:hugo.com

    If you spread out the expansion logically into its individual parts, it looks like this:

    exim -be '${reduce {<; ${readfile{/etc/exim/test_list.cf}{;}} } 
             {}
             {${if or{ {match{$item}{#}} {match{$item}{#}} } 
                 {$value}
                 {$value:${sg{${extract{1}{:}{$item}}} {^.*@} {}}}}
             }
           }
         '

    One thing that still needs to be fixed is that leading : should not be there. I'm not 100% sure why it is there :-/ and I don't really have the time to delve any further into it. The logic needs to be massaged a bit to catch whatever condition is causing that leading colon to appear and then the result should be a domain list that you can use as a condition.

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