sendmail, 4th Edition

$digit

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Copy by position

RHS operator

The LHS wildcard operators ( $* , $+ , $- , and $@ ) and the LHS class-matching operators ( $= and $~ ) can have their matched values copied to the RHS by the $ digit positional operator. Consider, for example, the following rule:

 R $+ < @ $- . $* >        $: 

Here, there are three wildcard operators in the LHS. The first (the $+ ) corresponds to the $1 on the RHS. The object of this rule is to match a focused address and rewrite it as the username. For example, [e-mail] will be rewritten to be gw .

The $ digit operator can be used only on the RHS of rules. See Section 18.7.1 in this chapter for a full description of this $ digit operator.