GNU make

Short Table of Contents

1 Overview of make
2 An Introduction to Makefiles
3 Writing Makefiles
4 Writing Rules
5 Writing Recipes in Rules
6 How to Use Variables
7 Conditional Parts of Makefiles
8 Functions for Transforming Text
9 How to Run make
10 Using Implicit Rules
11 Using make to Update Archive Files
12 Extending GNU make
13 Integrating GNU make
14 Features of GNU make
15 Incompatibilities and Missing Features
16 Makefile Conventions
Appendix A Quick Reference
Appendix B Errors Generated by Make
Appendix C Complex Makefile Example
Appendix D GNU Free Documentation License
Index of Concepts
Index of Functions, Variables, & Directives

GNU make

This file documents the GNU make utility, which determines automatically which pieces of a large program need to be recompiled, and issues the commands to recompile them.

This is Edition 0.75, last updated 17 January 2020, of The GNU Make Manual, for GNU make version 4.3.

Copyright © 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020 Free Software Foundation, Inc.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, with the Front-Cover Texts being “A GNU Manual,” and with the Back-Cover Texts as in (a) below. A copy of the license is included in the section entitled “GNU Free Documentation License.”
(a) The FSF’s Back-Cover Text is: “You have the freedom to copy and modify this GNU manual. Buying copies from the FSF supports it in developing GNU and promoting software freedom.”

• Overview		Overview of `make`.
• Introduction		An introduction to `make`.
• Makefiles		Makefiles tell `make` what to do.
• Rules		Rules describe when a file must be remade.
• Recipes		Recipes say how to remake a file.
• Using Variables		You can use variables to avoid repetition.
• Conditionals		Use or ignore parts of the makefile based on the values of variables.
• Functions		Many powerful ways to manipulate text.
• Invoking make		How to invoke `make` on the command line.
• Implicit Rules		Use implicit rules to treat many files alike, based on their file names.
• Archives		How `make` can update library archives.
• Extending make		Using extensions to `make`.
• Integrating make		Integrating `make` with other tools.
• Features		Features GNU `make` has over other `make`s.
• Missing		What GNU `make` lacks from other `make`s.
• Makefile Conventions		Conventions for writing makefiles for GNU programs.
• Quick Reference		A quick reference for experienced users.
• Error Messages		A list of common errors generated by `make`.
• Complex Makefile		A real example of a straightforward, but nontrivial, makefile.

• GNU Free Documentation License		License for copying this manual.
• Concept Index		Index of Concepts.
• Name Index		Index of Functions, Variables, & Directives.

— The Detailed Node Listing — Overview of make
• Preparing		Preparing and running `make`.
• Reading		On reading this text.
• Bugs		Problems and bugs.
An Introduction to Makefiles
• Rule Introduction		What a rule looks like.
• Simple Makefile		A simple makefile.
• How Make Works		How `make` processes this makefile.
• Variables Simplify		Variables make makefiles simpler.
• make Deduces		Letting `make` deduce the recipes.
• Combine By Prerequisite		Another style of makefile.
• Cleanup		Rules for cleaning the directory.
Writing Makefiles
• Makefile Contents		What makefiles contain.
• Makefile Names		How to name your makefile.
• Include		How one makefile can use another makefile.
• MAKEFILES Variable		The environment can specify extra makefiles.
• Remaking Makefiles		How makefiles get remade.
• Overriding Makefiles		How to override part of one makefile with another makefile.
• Reading Makefiles		How makefiles are read in.
• Parsing Makefiles		How makefiles are parsed.
• Secondary Expansion		How and when secondary expansion is performed.
What Makefiles Contain
• Splitting Lines		Splitting long lines in makefiles
Writing Rules
• Rule Example		An example explained.
• Rule Syntax		General syntax explained.
• Prerequisite Types		There are two types of prerequisites.
• Wildcards		Using wildcard characters such as ‘*’.
• Directory Search		Searching other directories for source files.
• Phony Targets		Using a target that is not a real file’s name.
• Force Targets		You can use a target without a recipe or prerequisites to mark other targets as phony.
• Empty Targets		When only the date matters and the files are empty.
• Special Targets		Targets with special built-in meanings.
• Multiple Targets		When to make use of several targets in a rule.
• Multiple Rules		How to use several rules with the same target.
• Static Pattern		Static pattern rules apply to multiple targets and can vary the prerequisites according to the target name.
• Double-Colon		How to use a special kind of rule to allow several independent rules for one target.
• Automatic Prerequisites		How to automatically generate rules giving prerequisites from source files themselves.
Using Wildcard Characters in File Names
• Wildcard Examples		Several examples.
• Wildcard Pitfall		Problems to avoid.
• Wildcard Function		How to cause wildcard expansion where it does not normally take place.
Searching Directories for Prerequisites
• General Search		Specifying a search path that applies to every prerequisite.
• Selective Search		Specifying a search path for a specified class of names.
• Search Algorithm		When and how search paths are applied.
• Recipes/Search		How to write recipes that work together with search paths.
• Implicit/Search		How search paths affect implicit rules.
• Libraries/Search		Directory search for link libraries.
Static Pattern Rules
• Static Usage		The syntax of static pattern rules.
• Static versus Implicit		When are they better than implicit rules?
Writing Recipes in Rules
• Recipe Syntax		Recipe syntax features and pitfalls.
• Echoing		How to control when recipes are echoed.
• Execution		How recipes are executed.
• Parallel		How recipes can be executed in parallel.
• Errors		What happens after a recipe execution error.
• Interrupts		What happens when a recipe is interrupted.
• Recursion		Invoking `make` from makefiles.
• Canned Recipes		Defining canned recipes.
• Empty Recipes		Defining useful, do-nothing recipes.
Recipe Syntax
• Splitting Recipe Lines		Breaking long recipe lines for readability.
• Variables in Recipes		Using `make` variables in recipes.
Recipe Execution
• One Shell		One shell for all lines in a recipe.
• Choosing the Shell		How `make` chooses the shell used to run recipes.
Parallel Execution
• Parallel Output		Handling output during parallel execution
• Parallel Input		Handling input during parallel execution
Recursive Use of make
• MAKE Variable		The special effects of using ‘`$(MAKE)`’.
• Variables/Recursion		How to communicate variables to a sub-`make`.
• Options/Recursion		How to communicate options to a sub-`make`.
• -w Option		How the ‘`-w`’ or ‘`--print-directory`’ option helps debug use of recursive `make` commands.
How to Use Variables
• Reference		How to use the value of a variable.
• Flavors		Variables come in two flavors.
• Advanced		Advanced features for referencing a variable.
• Values		All the ways variables get their values.
• Setting		How to set a variable in the makefile.
• Appending		How to append more text to the old value of a variable.
• Override Directive		How to set a variable in the makefile even if the user has set it with a command argument.
• Multi-Line		An alternate way to set a variable to a multi-line string.
• Undefine Directive		How to undefine a variable so that it appears as if it was never set.
• Environment		Variable values can come from the environment.
• Target-specific		Variable values can be defined on a per-target basis.
• Pattern-specific		Target-specific variable values can be applied to a group of targets that match a pattern.
• Suppressing Inheritance		Suppress inheritance of variables.
• Special Variables		Variables with special meaning or behavior.
Advanced Features for Reference to Variables
• Substitution Refs		Referencing a variable with substitutions on the value.
• Computed Names		Computing the name of the variable to refer to.
Conditional Parts of Makefiles
• Conditional Example		Example of a conditional
• Conditional Syntax		The syntax of conditionals.
• Testing Flags		Conditionals that test flags.
Functions for Transforming Text
• Syntax of Functions		How to write a function call.
• Text Functions		General-purpose text manipulation functions.
• File Name Functions		Functions for manipulating file names.
• Conditional Functions		Functions that implement conditions.
• Foreach Function		Repeat some text with controlled variation.
• File Function		Write text to a file.
• Call Function		Expand a user-defined function.
• Value Function		Return the un-expanded value of a variable.
• Eval Function		Evaluate the arguments as makefile syntax.
• Origin Function		Find where a variable got its value.
• Flavor Function		Find out the flavor of a variable.
• Make Control Functions		Functions that control how make runs.
• Shell Function		Substitute the output of a shell command.
• Guile Function		Use GNU Guile embedded scripting language.
How to Run make
• Makefile Arguments		How to specify which makefile to use.
• Goals		How to use goal arguments to specify which parts of the makefile to use.
• Instead of Execution		How to use mode flags to specify what kind of thing to do with the recipes in the makefile other than simply execute them.
• Avoiding Compilation		How to avoid recompiling certain files.
• Overriding		How to override a variable to specify an alternate compiler and other things.
• Testing		How to proceed past some errors, to test compilation.
• Options Summary		Summary of Options
Using Implicit Rules
• Using Implicit		How to use an existing implicit rule to get the recipes for updating a file.
• Catalogue of Rules		A list of built-in rules.
• Implicit Variables		How to change what predefined rules do.
• Chained Rules		How to use a chain of implicit rules.
• Pattern Rules		How to define new implicit rules.
• Last Resort		How to define a recipe for rules which cannot find any.
• Suffix Rules		The old-fashioned style of implicit rule.
• Implicit Rule Search		The precise algorithm for applying implicit rules.
Defining and Redefining Pattern Rules
• Pattern Intro		An introduction to pattern rules.
• Pattern Examples		Examples of pattern rules.
• Automatic Variables		How to use automatic variables in the recipe of implicit rules.
• Pattern Match		How patterns match.
• Match-Anything Rules		Precautions you should take prior to defining rules that can match any target file whatever.
• Canceling Rules		How to override or cancel built-in rules.
Using make to Update Archive Files
• Archive Members		Archive members as targets.
• Archive Update		The implicit rule for archive member targets.
• Archive Pitfalls		Dangers to watch out for when using archives.
• Archive Suffix Rules		You can write a special kind of suffix rule for updating archives.
Implicit Rule for Archive Member Targets
• Archive Symbols		How to update archive symbol directories.
Extending GNU make
• Guile Integration		Using Guile as an embedded scripting language.
• Loading Objects		Loading dynamic objects as extensions.
GNU Guile Integration
• Guile Types		Converting Guile types to `make` strings.
• Guile Interface		Invoking `make` functions from Guile.
• Guile Example		Example using Guile in `make`.
Loading Dynamic Objects
• load Directive		Loading dynamic objects as extensions.
• Remaking Loaded Objects		How loaded objects get remade.
• Loaded Object API		Programmatic interface for loaded objects.
• Loaded Object Example		Example of a loaded object
Integrating GNU make
• Job Slots		Share job slots with GNU `make`.
• Terminal Output		Control output to terminals.
Sharing Job Slots with GNU make
• POSIX Jobserver		Using the jobserver on POSIX systems.
• Windows Jobserver		Using the jobserver on Windows systems.

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GNU make

Short Table of Contents

Table of Contents

GNU make