Hello.
On Fri, Dec 19, 2025 at 02:59:18PM -0600, Johnnie Adams via Exim-users wrote:
> Thanks! Here's the new result for a bracketed period:
[ trace skipped]
> As you can see, the escaped periods give a faulty result, while the
> bracketed period gives the right result and panics the application.
> Neither of those states is ideal.
No. Skipped trace shows that
1. Bracketed period "[.]list" regular expression is NOT used, because
outer lookup fails, and its failure is programmed to eject "fail"
exception.
2. Escaped period "\.list" is successfully compiled to RE=".list" and
successfully applied to the string "johnnies-test-list-2.list", making
two substitutions: first "-list" is removed, then ".list" is removed.
This is because dot (.) in RE is interpreted as "any character".
Resulting string after ${sg..} is "johnnies-test-2", as it should be.
Manual says:
${sg{<subject>}{<regex>}{<replacement>}}
This item works like Perl’s substitution operator (s) with the
global (/g) option; hence its name.
Perl's "global" (/g) means "repeated use over whole string, single pass".
So two matches occur, leading to two substitutions.
Note that RE=".list" is not identical to RE="[.]list", because first
means "any character followed by string 'list'", and second means
"dot character followed by string 'list'" (same as RE="\.list").
This is how regex engine works. You can play with "exim -be" to test it:
exim -be -d-all+expand '${sg{aa..bb}{\.}{c}}'
exim -be -d-all+expand '${sg{aa..bb}{[.]}{c}}'
exim -be -d-all+expand '${sg{aa..bb}{\\\.}{c}}'
--
Eugene Berdnikov
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