B.5.2 Macro definitions

Macro definitions take the form define macroname definition. In such a macro definition, the environment variable macroname is defined to expand to the value definition. Before the definition is made, however, any macros used in definition are expanded.

Please note the following nuances of macro usage:

• For the purposes of this section, macro and environment variable are synonyms.
• Macros may not take arguments.
• Macros may not recurse.
• Macros are just environment variable definitions like other environment variable definitions, with the exception that they are limited in scope to the devices configuration file.
• Macros override other all environment variables of the same name (within the scope of devices).
• Earlier macro definitions for a particular key override later ones. In particular, macro definitions on the command line override those in the device definition file. See Non-option Arguments.
• There are two predefined macros, whose values are determined at runtime:

  viewwidth

  Defined as the width of the console screen, in columns of text.
  

  viewlength

  Defined as the length of the console screen, in lines of text.