sendmail, 4th Edition

The RHS

The purpose of the RHS in a rule is to rewrite the workspace. To make this rewriting more versatile, sendmail offers several special RHS operators. The complete list is shown in Table 18-3.

Table 18-3. RHS operators

RHS	§	Description or use
$digit	Copy by Position: $digit on page 661	Copy by position.
$:	Rewrite Once Prefix: $: on page 662	Rewrite once (when used as a prefix), or specify the user in a delivery agent “triple,” or specify the default value to return on a failed database-map lookup.
$@	Rewrite-and-Return Prefix: $@ on page 664	Rewrite and return (when used as a prefix), or specify the host in a delivery-agent “triple,” or specify an argument to pass in a database-map lookup or action.
$>set	Rewrite Through a Rule Set: $>set on page 664	Rewrite through another rule set (such as a subroutine call that returns to the current position).
$#	Return a Selection: $# on page 667	Specify a delivery agent or choose an action, such as to reject or discard a recipient, sender, connection, or message.
$[ $]	Canonicalize Hostname: $[ and $] on page 668	Canonicalize the hostname.
$( $)	Use $( and $) in Rules on page 892	Perform a lookup in an external database, file, or network service, or perform a change (such as dequoting), or store a value into a macro.
$&	Use Value As Is with $& on page 793	Delay conversion of a macro until runtime.