NAME
service.switch — indicate lookup sources and fallback mechanism
DESCRIPTION
/etc/mail/service.switch
is a
sendmail(1M)
service switch similar to
/etc/nsswitch.conf
(see
nsswitch.conf(4))
that indicates the lookup source for hostnames and aliases.
It consists of two lines, one for
hosts
and one for
aliases.
The lookup sources are listed after the
hosts
or
aliases
name.
For
hosts,
one or more of the following can be listed:
files (for /etc/hosts)
dns (for Domain Name Service)
nis (for NIS)
For
aliases,
one or more of the following can be listed:
files (for /etc/mail/aliases)
nis (for NIS)
Sample Configurations
- 1.
The default configuration for
service.switch
is to use
dns
for hostname lookups and the
aliases
file for aliases.
(Note that
due to a bug, the hostname lookup will never fallback to a file
lookup, so anything listed after
dns
will be ignored.)
hosts dns files
aliases files
- 2.
To work with a non-DNS
environment that uses file lookups
(/etc/hosts),
the following
service.switch
can be used:
hosts files
aliases files
- 3.
To work with a NIS environment that does not use DNS, the following
service.switch
can be used:
hosts nis files
aliases nis files
Modifying sendmail.cf
The
sendmail.cf
file must be modified to request the usage
of the
service.switch
file.
Otherwise, the default for
sendmail.cf
is to use DNS for hostname lookups, and
files
for alias lookups.
To use NIS or
files,
the following line must be
uncommented in
sendmail.cf:
#O ServiceSwitchFile=/etc/mail/service.switch
HISTORY
The
service.switch
file appeared in sendmail V8.
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