[Chapter 7] 7.4 Things to Try
Author: Bryan Costales & Eric Allman
Date: 1999-01-06T18:35:17Z

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| Chapter 7 Macros |

## 7.4 Things to Try

- Macro names that begin with uppercase letters are for your use. Names that begin with lowercase letters are reserved for sendmail's use. Twenty-seven special characters are also reserved by sendmail for use as operators. What happens if you try to define a macro whose name is another character, such as a tab or an underscore?

- What happens if you try to define a macro whose name is an operator?

- Using the `-d35.9` command-line switch, determine what happens if you define two macros, each with the same name.

- Any sendmail.cf command may be continued and extended by beginning the next line with a tab or a space. Using the `-d35.9` command-line switch, determine the effect of continuing a macro definition. For example,

  >     D{FOO}something
  >     tab   somethingmore

- The text value of a macro must immediately follow the name of that macro, with no intervening space. Can the text value contain arbitrary spaces or tabs?

- Using grep(1), find all the `D` commands in your site's actual sendmail.cf file. If you find any that begin with a lowercase letter and that you haven't seen before, try looking them up in Chapter 31, Defined Macros.

7.3 Predefined Macros |  | 8. Addresses and Rules