Name
switch
Synopsis
The
switch
database-map type is used internally by
sendmail to create sequence
types of database maps based on external service-switch files. The
lines inside a service-switch file look like this:
service how how
as, for example:
aliases files nis
This line tells sendmail to search for its aliases in files first, and then using NIS.
To illustrate the switch
type, consider the need
to look up aliases inside rule sets in the same way that
sendmail looks up its own aliases. To do this,
you would declare a switch
database map. For
example:
Kali switch aliases
This causes sendmail to search for the
service
named aliases
in the service-switch file. In this example it finds such a line, so
for each how
that follows the
aliases
in that line,
sendmail creates a new database map with the
name ali
followed by a dot and the
how :[18]
aliases files becomes ali.files aliases nis becomes ali.nis
These named database maps are then sequenced for you. Recall that
sequence
database maps are declared like this:
Kname sequence map1 map2,...
The name
given to the sequence is
ali
. In our example the following sequence
is automatically created for you from your original
switch
declaration:
Kali sequence ali.files ali.nis
In rule sets, when you look up aliases with the
ali
database map:
R... $( ali $1 $) ↑the sequence named ali
you will use the sequence
named
ali
that was automatically built for you from a
combination of your original switch
definition and
your service-switch file’s
aliases
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