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Chapter 9: How to Run make 99

9 How to Run make

A makeﬁle that says how to recompile a program can be used in more than one way. The

simplest use is to recompile every ﬁle that is out of date. Usually, makeﬁles are written so

that if you run make with no arguments, it does just that.

But you might want to update only some of the ﬁles; you might want to use a diﬀerent

compiler or diﬀerent compiler options; you might want just to ﬁnd out which ﬁles are out

of date without changing them.

By giving arguments when you run make, you can do any of these things and many

others.

The exit status of make is always one of three values:

0 The exit status is zero if make is successful.

2 The exit status is two if make encounters any errors. It will print messages

describing the particular errors.

1 The exit status is one if you use the ‘-q’ ﬂag and make determines that some

target is not already up to date. See Section 9.3 [Instead of Executing Recipes],

page 101.

9.1 Arguments to Specify the Makeﬁle

The way to specify the name of the makeﬁle is with the ‘-f’ or ‘--file’ option (‘--makefile’

also works). For example, ‘-f altmake’ says to use the ﬁle altmake as the makeﬁle.

If you use the ‘-f’ ﬂag several times and follow each ‘-f’ with an argument, all the

speciﬁed ﬁles are used jointly as makeﬁles.

If you do not use the ‘-f’ or ‘--file’ ﬂag, the default is to try GNUmakefile, makefile,

and Makefile, in that order, and use the ﬁrst of these three which exists or can be made

(see Chapter 3 [Writing Makeﬁles], page 11).

9.2 Arguments to Specify the Goals

The goals are the targets that make should strive ultimately to update. Other targets are

updated as well if they appear as prerequisites of goals, or prerequisites of prerequisites of

goals, etc.

By default, the goal is the ﬁrst target in the makeﬁle (not counting targets that start with

a period). Therefore, makeﬁles are usually written so that the ﬁrst target is for compiling

the entire program or programs they describe. If the ﬁrst rule in the makeﬁle has several

targets, only the ﬁrst target in the rule becomes the default goal, not the whole list. You can

manage the selection of the default goal from within your makeﬁle using the .DEFAULT_GOAL

variable (see Section 6.14 [Other Special Variables], page 73).

You can also specify a diﬀerent goal or goals with command line arguments to make.

Use the name of the goal as an argument. If you specify several goals, make processes each

of them in turn, in the order you name them.

Any target in the makeﬁle may be speciﬁed as a goal (unless it starts with ‘-’ or contains

an ‘=’, in which case it will be parsed as a switch or variable deﬁnition, respectively). Even

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Roland Ver. 4.5 Technical Information Seite 109