make: Rule Introduction
2.1 What a Rule Looks Like
==========================
A simple makefile consists of "rules" with the following shape:
TARGET ... : PREREQUISITES ...
RECIPE
...
...
A "target" is usually the name of a file that is generated by a
program; examples of targets are executable or object files. A target
can also be the name of an action to carry out, such as 'clean' (
Phony Targets).
A "prerequisite" is a file that is used as input to create the
target. A target often depends on several files.
A "recipe" is an action that 'make' carries out. A recipe may have
more than one command, either on the same line or each on its own line.
*Please note:* you need to put a tab character at the beginning of every
recipe line! This is an obscurity that catches the unwary. If you
prefer to prefix your recipes with a character other than tab, you can
set the '.RECIPEPREFIX' variable to an alternate character (
Special Variables).
Usually a recipe is in a rule with prerequisites and serves to create
a target file if any of the prerequisites change. However, the rule
that specifies a recipe for the target need not have prerequisites. For
example, the rule containing the delete command associated with the
target 'clean' does not have prerequisites.
A "rule", then, explains how and when to remake certain files which
are the targets of the particular rule. 'make' carries out the recipe
on the prerequisites to create or update the target. A rule can also
explain how and when to carry out an action. Writing Rules
Rules.
A makefile may contain other text besides rules, but a simple
makefile need only contain rules. Rules may look somewhat more
complicated than shown in this template, but all fit the pattern more or
less.
Info Catalog
make: Introduction
make: Introduction
make: Simple Makefile