make
The make utility automatically determines which pieces of a large
program need to be recompiled, and issues commands to recompile them.
This manual describes GNU make, which was implemented by Richard
Stallman and Roland McGrath. GNU make conforms to section 6.2 of
IEEE Standard 1003.2-1992 (POSIX.2).
Our examples show C programs, since they are most common, but you can use
make with any programming language whose compiler can be run with a
shell command. Indeed, make is not limited to programs. You can
use it to describe any task where some files must be updated automatically
from others whenever the others change.
To prepare to use make, you must write a file called
the makefile that describes the relationships among files
in your program and provides commands for updating each file.
In a program, typically, the executable file is updated from object
files, which are in turn made by compiling source files.
Once a suitable makefile exists, each time you change some source files, this simple shell command:
make
suffices to perform all necessary recompilations. The make program
uses the makefile data base and the last-modification times of the files to
decide which of the files need to be updated. For each of those files, it
issues the commands recorded in the data base.
You can provide command line arguments to make to control which
files should be recompiled, or how. See section How to Run make.
If you are new to make, or are looking for a general
introduction, read the first few sections of each chapter, skipping the
later sections. In each chapter, the first few sections contain
introductory or general information and the later sections contain
specialized or technical information.
The exception is the second chapter, section An Introduction to Makefiles, all of which is introductory.
If you are familiar with other make programs, see section Features of GNU make, which lists the enhancements GNU
make has, and section Incompatibilities and Missing Features, which explains the few things GNU make lacks that
others have.
For a quick summary, see section Summary of Options, section Quick Reference, and section Special Built-in Target Names.
If you have problems with GNU make or think you've found a bug,
please report it to the developers; we cannot promise to do anything but
we might well want to fix it.
Before reporting a bug, make sure you've actually found a real bug. Carefully reread the documentation and see if it really says you can do what you're trying to do. If it's not clear whether you should be able to do something or not, report that too; it's a bug in the documentation!
Before reporting a bug or trying to fix it yourself, try to isolate it
to the smallest possible makefile that reproduces the problem. Then
send us the makefile and the exact results make gave you. Also
say what you expected to occur; this will help us decide whether the
problem was really in the documentation.
Once you've got a precise problem, please send electronic mail to:
bug-make@gnu.org
Please include the version number of make you are using. You can
get this information with the command `make --version'.
Be sure also to include the type of machine and operating system you are
using. If possible, include the contents of the file `config.h'
that is generated by the configuration process.
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