The sendmail.cf file is line-oriented, with one configuration command per line. Each configuration command consists of a single letter[1] that must begin a line. Each letter is followed by other information as required by the purpose of the particular command.
[1] A quick bit of trivia: initially, there was almost nothing in the configuration file except R rules (and there was only one rule set). Eric recalls adding M and O fairly quickly. Commands such as K and V came quite late.
In addition to commands, the configuration file can also have lines that begin with a # to form a comment line, or with a tab or space character to form a continuation line. A list of all legal characters that can begin a line in the configuration file is shown in Table 17-1.
Command |
§ |
Version |
Description |
---|---|---|---|
# |
Section 17.2 |
All |
A comment line, ignored |
space |
Section 17.4 |
All |
Continue the previous line |
tab |
Section 17.4 |
All |
Continue the previous line |
C |
Section 22.1 |
All |
Define a class macro |
D |
Section 21.3 |
All |
Define a sendmail macro |
E |
Section 10.2.1 |
V8.7 and above |
Environment for agents |
F |
Section 22.1 |
All |
Define a class macro from a file or a pipe |
H |
Section 25.1 |
All |
Define a header |
K |
Section 23.2 |
V8.1 and above |
Create a keyed map entry |
L |
Obsolete |
Extended load average |
|
M |
Section 20.1 |
All |
Define a mail delivery agent |
O |
Section 24.3 |
All |
Define an option |
P |
Section 25.10 |
All |
Define delivery priorities |
Q |
Section 11.4.2 |
V8.12 and above |
Declare queue groups |
R |
Section 18.2 |
All |
Define a transformation rule |
S |
Section 19.1 |
All |
Declare a rule-set start |
T |
Section 10.8.1.1 |
All |
Declare trusted users (ignored V8.1-V8.6) |
V |
Section 17.5 |
V8.1 and above |
Version of configuration file |
X |
Section 7.6.2 |
V8.12 and above |
Define a mail filter for use |
Most configuration commands are so complex that each requires a chapter or two of its own. A few, however, are simple. In this chapter we will describe the simple ones: comments, continuation lines, and the V (version) command.