To shorten makefile, make has a set of default rules if the update
action is missing. The activation of these default action is triggered by
the file extension of the source and the target file. Many of these rules
use implicitly some make macro names to allow configuration. New default
actions may be defined in the makefile by using the following definition:
This defines that a file with the extension destext is created from a file with the extension srcext by executing the update commands actions. This is similar to a standard dependence definition using a wildcard for the name.
In make there are default rules to activate the assembler, all different types of compilers, the parser generators YACC and LEX. This helps to minimize the size of the description files for larger projects.