sendmail, 4th Edition

Define a Macro with .D

The .D rule-testing command is used to define a sendmail macro. One use for this command might be to modify a rule that depends on the $& prefix (Use Value As Is with $& on page 793). For example, consider this small configuration file that contains a rule in parse rule set 0 that is intended to deliver a local user’s address via the local delivery agent:

V10
Sparse=0
R$+      $#local $@ $&X $: $1

If $X has a value, this rule returns that value as the host (the $@) part of a parse rule set 0 triple (The parse Rule Set 0 on page 696). If $X lacks a value, the host part is empty. This technique is useful because the $@ part with the local delivery agent is used to implement plussed users (Plussed Detail Addressing on page 476).

This scheme can be tested in rule-testing mode by first specifying a local user with $X undefined:

% /usr/sbin/sendmail -bt -Ctest.cf
ADDRESS TEST MODE (ruleset 3 NOT automatically invoked)
Enter <ruleset> <address>
> parse bob
parse              input: bob
parse            returns: $# local $@ $: bob

This form of rule testing and the output produced are described in detail in Process-Specified Addresses on page 314. Here, it is important only to note that the host part of the triple (the $@ part) is empty.

Now, use the .D command to give $X the value home:

> .DXhome

Now, test those rules again:

> parse bob
parse              input: bob
parse            returns: $# local $@ home $: bob

This time the host part of the triple (the $@ part) has the value home as intended.

The .D command can also be used ...