Ok thanks all, I didn't realize the 'm' thing was part of Perl regex. I
came from using java regular expressions where I don't deal with the '/' and
'm' characters.
Bowie Bailey wrote:
>
> On 6/16/2011 11:05 AM, raiden031 wrote:
>> So I'm trying to understand the spamAssassin rules, and I found a couple
>> of
>> things that don't make sense about the rules I downloaded.
>
> SpamAssassin uses Perl regular expressions. For more info, look that up
> on Google and you should be able to find plenty of info.
>
>> 1) Some of the header, body, and uri rules have regular expressions that
>> are
>> not enclosed in '/' (ie. /pattern/i ). Instead they are enclosed with
>> 'm'
>> followed by another character.
>>
>> I have seen the following different ways to enclose a pattern:
>>
>> /pattern/i # As documented
>> m{pattern}i
>> m'pattern'i
>> m%pattern%i
>> m!pattern!i
>>
>> Example below:
>>
>> uri FU_END_ET m'/et/$'i
>>
>> Is this valid and if so, why is it being done?
>
> This is done to make a pattern more readable (mainly to avoid the
> necessity of escaping the '/' character).
>
> For example, both of these patterns will match a series of three slashes:
>
> /\/\/\//
> m'///'
>
> When you use the 'm' form, you can use almost any separator you want.
> The examples you gave above are some of the most common. You generally
> want to pick a separator character that does not appear in the expression.
>
> FYI: The 'i' at the end of the patterns above is a pattern modifier
> that makes the expression case-insensitive.
>
>> 2) I don't understand the use of the '!~' for header rules. The
>> documentation says '=~' means 'contains a regular expression' but '!~'
>> means
>> 'does not contain a regular expression'. Yet in both cases, there is a
>> regular expression associated with the rule.
>>
>> header FH_FROMEML_NOTLD From:addr !~ /\./ [if-unset: f...@bar.com]
>> describe FH_FROM_EML_NOTLD E-mail address doesn't have TLD (.com, etc.)
>>
>> For instance, could someone explain how the above rule works? It looks
>> like
>> to me it should hit whenever there is any From address populated
>> regardless
>> of whether there's a .com or not.
>
> The '!~' form means that the rule matches when the regular expression
> does NOT match.
>
> For example:
>
> From:addr !~ /\./
>
> The above pattern will match on any from address that does NOT contain a
> period.
>
> --
> Bowie
>
>
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