GNU make - Appending Go to the first , previous , next , last section, table of contents .
Often it is useful to add more text to the value of a variable already defined. See section The Two Flavors of Variables , for an explanation of the two flavors of variables. Recall that when you define a recursively-expanded variable, make does not expand the value you set for variable and function references immediately. The importance of this comes when the variable's old value contains variable references. Thus, includes need not be defined yet for its value to take effect.