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/GNU Make

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.

• 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 makes.
• Missing What GNU make lacks from other makes.
• 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.

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.
Licensed under the GNU Free Documentation License.
https://www.gnu.org/software/make/manual/html_node/index.html