Adding Rules To Any Ruleset When Using M4

This is a posting I made to comp.mail.sendmail

When adding a custom rule a ruleset using M4 and not using the LOCAL_RULE_* tags you do have some control over where in ruleset your rule will be added. You can add it to the beginning or the end of the ruleset. If you redefine a ruleset sendmail reopens the ruleset if it has already been defined. So if you add the rule with the tag LOCAL_CONFIG you will define your rule in ruleset S11 before the normal definition of ruleset S11, so your rule will be at the beginning. If you add your rule with the sendmail M4 macros then the rule will be added to the end of your file so the rule will be added to the end of ruleset S11.

	# added with `PUSHDIVERT(8)'
	R $-		$@ $1@<>

Now the / required a bit of digging on my part. M4 diversion 8 is a diversion that is not used by sendmail. Since the sendmail M4 templates do not and this diversion, I think what happens is that M4 does the (include in the output stream) at the end of the process.

Here is my M4 template:

	# added with `LOCAL_CONFIG' harker
	Rlocal_config		test

	# added with `PUSHDIVERT' harker
	Rpushdivert		test
Here is what ruleset S11 looks like in address test mode:
	sendmail -bt -C./
	> =S11					(Print ruleset S11)
>>>	Rlocal_config		test 
	R$+			$: $> 51 $1 
	R$* : ; < @ >		$@ 
	R$*			$: $> 61 $1 
	R$+			$: $> 94 $1 
>>>	Rpushdivert		test 

A detail to remeber about LOCAL_CONFIG is that this tag adds things to the top of the file, after the standard macro, class, and map (database) definitions, but before the options, trusted users and header definitions. In particular if you are adding additional charaters to the option OperatorChars and you are using those charaters in the rules you are adding, you will need to set the option in the LOCAL_CONFIG section, before the rule you are adding:
   O OperatorChars=.:%@!^/[]+yourchars
This is needed so that sendmail knows about the new characters as being token separators before it parses the rules you are adding.

You will still need to defind the confOPERATORS M4 macro so that the option does not get reset to its normal value later on in the file:

I think this counts as a "Harker's Helpful Hint" or maybe just a "Stupid sendmail pet trick" (:-)