Rules

This is the general format of a rule:

targets [attributes]
ruleop [prerequisites] [; recipe ]
{<tab> recipe}

You need to include items enclosed by [ ]; items within { } can appear zero or more times. In a rule:

targets

Represents a list of one or more dependent files.

attributes

Represents a list, possibly empty, of attributes to apply to the list of targets. See Using attributes to control updates for more details.

ruleop

Represents an operator that separates the target names from the prerequisite names, and optionally affects the processing of the specified targets. All rule operators begin with a colon (:). For more information about rule operators, see Rule operators.

prerequisites

Represents a list of filenames on which the specified targets depend.

recipe

May follow on the same line as the prerequisites, separated from them by a semicolon. If such a recipe exists, make uses it as the first in a list of recipe lines defining a method for remaking the named targets. Additional recipe lines may follow the first line of the rule. Each such recipe line must begin with a tab character. For more about recipes, see Recipes.

As an example of a simple rule, consider the following:

main.o : include.h

This rule contains a single target, main.o, and a single prerequisite, include.h. The rule states that if include.h changes, main.o will require remaking. A typical makefile does not specify a recipe for making main.o from main.c; instead, the default rules provide the recipe using a metarule or suffix rule. These rules are discussed in Using inference rules.