GNU make

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

This edition of the GNU Make Manual, last updated 08 July 2002, documents GNU make Version 3.80.

This manual describes make and contains the following chapters:

1. Overview of make
2. An Introduction to Makefiles		An introduction to make.
3. Writing Makefiles		Makefiles tell make what to do.
4. Writing Rules		Rules describe when a file must be remade.
5. Writing the Commands in Rules		Commands say how to remake a file.
6. How to Use Variables		You can use variables to avoid repetition.
7. Conditional Parts of Makefiles		Use or ignore parts of the makefile based on the values of variables.
8. Functions for Transforming Text		Many powerful ways to manipulate text.
9. How to Run make		How to invoke make on the command line.
10. Using Implicit Rules		Use implicit rules to treat many files alike, based on their file names.
11. Using make to Update Archive Files		How make can update library archives.
12. Features of GNU make		Features GNU make has over other makes.
13. Incompatibilities and Missing Features		What GNU make lacks from other makes.
14. Makefile Conventions		Conventions for writing makefiles for GNU programs.
A. Quick Reference		A quick reference for experienced users.
B. Errors Generated by Make		A list of common errors generated by make.
C. Complex Makefile Example		A real example of a straightforward, but nontrivial, makefile.

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

 -- The Detailed Node Listing ---

Overview of make

Preparing and Running Make
1.1 How to Read This Manual		On Reading this Text
1.2 Problems and Bugs

An Introduction to Makefiles

2.1 What a Rule Looks Like		What a rule looks like.
2.2 A Simple Makefile
2.3 How make Processes a Makefile		How make Processes This Makefile
2.4 Variables Make Makefiles Simpler
2.5 Letting make Deduce the Commands
2.6 Another Style of Makefile
2.7 Rules for Cleaning the Directory

Writing Makefiles

3.1 What Makefiles Contain		What makefiles contain.
3.2 What Name to Give Your Makefile		How to name your makefile.
3.3 Including Other Makefiles		How one makefile can use another makefile.
3.4 The Variable MAKEFILES		The environment can specify extra makefiles.
3.5 The Variable MAKEFILE_LIST		Discover which makefiles have been read.
3.6 Other Special Variables		Other special variables.
3.7 How Makefiles Are Remade		How makefiles get remade.
3.8 Overriding Part of Another Makefile		How to override part of one makefile with another makefile.
3.9 How make Reads a Makefile		How makefiles are parsed.

Writing Rules

4.1 Rule Example		An example explained.
4.2 Rule Syntax		General syntax explained.
4.3 Types of Prerequisites		There are two types of prerequisites.
4.4 Using Wildcard Characters in File Names		Using wildcard characters such as `*'.
4.5 Searching Directories for Prerequisites		Searching other directories for source files.
4.6 Phony Targets		Using a target that is not a real file's name.
4.7 Rules without Commands or Prerequisites		You can use a target without commands or prerequisites to mark other targets as phony.
4.8 Empty Target Files to Record Events		When only the date matters and the files are empty.
4.9 Special Built-in Target Names		Targets with special built-in meanings.
4.10 Multiple Targets in a Rule		When to make use of several targets in a rule.
4.11 Multiple Rules for One Target		How to use several rules with the same target.
4.12 Static Pattern Rules		Static pattern rules apply to multiple targets and can vary the prerequisites according to the target name.
4.13 Double-Colon Rules		How to use a special kind of rule to allow several independent rules for one target.
4.14 Generating Prerequisites Automatically		How to automatically generate rules giving prerequisites from source files themselves.

Using Wildcard Characters in File Names

4.4.1 Wildcard Examples		Several examples
4.4.2 Pitfalls of Using Wildcards		Problems to avoid.
4.4.3 The Function wildcard		How to cause wildcard expansion where it does not normally take place.

Searching Directories for Prerequisites

4.5.1 VPATH: Search Path for All Prerequisites		Specifying a search path that applies to every prerequisite.
4.5.2 The vpath Directive		Specifying a search path for a specified class of names.
4.5.3 How Directory Searches are Performed		When and how search paths are applied.
4.5.4 Writing Shell Commands with Directory Search		How to write shell commands that work together with search paths.
4.5.5 Directory Search and Implicit Rules		How search paths affect implicit rules.
4.5.6 Directory Search for Link Libraries		Directory search for link libraries.

Static Pattern Rules

4.12.1 Syntax of Static Pattern Rules		The syntax of static pattern rules.
4.12.2 Static Pattern Rules versus Implicit Rules		When are they better than implicit rules?

Writing the Commands in Rules

5.1 Command Echoing		How to control when commands are echoed.
5.2 Command Execution		How commands are executed.
5.3 Parallel Execution		How commands can be executed in parallel.
5.4 Errors in Commands		What happens after a command execution error.
5.5 Interrupting or Killing make		What happens when a command is interrupted.
5.6 Recursive Use of make		Invoking make from makefiles.
5.7 Defining Canned Command Sequences		Defining canned sequences of commands.
5.8 Using Empty Commands		Defining useful, do-nothing commands.

Recursive Use of make

5.6.1 How the MAKE Variable Works		The special effects of using `$(MAKE)'.
5.6.2 Communicating Variables to a Sub-make		How to communicate variables to a sub-make.
5.6.3 Communicating Options to a Sub-make		How to communicate options to a sub-make.
5.6.4 The `--print-directory' Option		How the `-w' or `--print-directory' option helps debug use of recursive make commands.

How to Use Variables

6.1 Basics of Variable References		How to use the value of a variable.
6.2 The Two Flavors of Variables		Variables come in two flavors.
6.3 Advanced Features for Reference to Variables		Advanced features for referencing a variable.
6.4 How Variables Get Their Values		All the ways variables get their values.
6.5 Setting Variables		How to set a variable in the makefile.
6.6 Appending More Text to Variables		How to append more text to the old value of a variable.
6.7 The override Directive		How to set a variable in the makefile even if the user has set it with a command argument.
6.8 Defining Variables Verbatim		An alternate way to set a variable to a verbatim string.
6.9 Variables from the Environment		Variable values can come from the environment.
6.10 Target-specific Variable Values		Variable values can be defined on a per-target basis.
6.11 Pattern-specific Variable Values		Target-specific variable values can be applied to a group of targets that match a pattern.

Advanced Features for Reference to Variables

6.3.1 Substitution References		Referencing a variable with substitutions on the value.
6.3.2 Computed Variable Names		Computing the name of the variable to refer to.

Conditional Parts of Makefiles

7.1 Example of a Conditional		Example of a conditional
7.2 Syntax of Conditionals		The syntax of conditionals.
7.3 Conditionals that Test Flags		Conditionals that test flags.

Functions for Transforming Text

8.1 Function Call Syntax		How to write a function call.
8.2 Functions for String Substitution and Analysis		General-purpose text manipulation functions.
8.3 Functions for File Names		Functions for manipulating file names.
8.4 The foreach Function		Repeat some text with controlled variation.
8.5 The if Function		Conditionally expand a value.
8.6 The call Function		Expand a user-defined function.
8.7 The value Function		Return the un-expanded value of a variable.
8.8 The eval Function		Evaluate the arguments as makefile syntax.
8.9 The origin Function		Find where a variable got its value.
8.10 The shell Function		Substitute the output of a shell command.
8.11 Functions That Control Make		Functions that control how make runs.

How to Run make

9.1 Arguments to Specify the Makefile		How to specify which makefile to use.
9.2 Arguments to Specify the Goals		How to use goal arguments to specify which parts of the makefile to use.
9.3 Instead of Executing the Commands		How to use mode flags to specify what kind of thing to do with the commands in the makefile other than simply execute them.
9.4 Avoiding Recompilation of Some Files		How to avoid recompiling certain files.
9.5 Overriding Variables		How to override a variable to specify an alternate compiler and other things.
9.6 Testing the Compilation of a Program		How to proceed past some errors, to test compilation.
9.7 Summary of Options

Using Implicit Rules

10.1 Using Implicit Rules		How to use an existing implicit rule to get the commands for updating a file.
10.2 Catalogue of Implicit Rules		A list of built-in implicit rules.
10.3 Variables Used by Implicit Rules		How to change what predefined rules do.
10.4 Chains of Implicit Rules		How to use a chain of implicit rules.
10.5 Defining and Redefining Pattern Rules		How to define new implicit rules.
10.6 Defining Last-Resort Default Rules		How to defining commands for rules which cannot find any.
10.7 Old-Fashioned Suffix Rules		The old-fashioned style of implicit rule.
10.8 Implicit Rule Search Algorithm		The precise algorithm for applying implicit rules.

Defining and Redefining Pattern Rules

10.5.1 Introduction to Pattern Rules		An introduction to pattern rules.
10.5.2 Pattern Rule Examples		Examples of pattern rules.
10.5.3 Automatic Variables		How to use automatic variables in the commands of implicit rules.
10.5.4 How Patterns Match		How patterns match.
10.5.5 Match-Anything Pattern Rules		Precautions you should take prior to defining rules that can match any target file whatever.
10.5.6 Canceling Implicit Rules		How to override or cancel built-in rules.

Using make to Update Archive Files

11.1 Archive Members as Targets		Archive members as targets.
11.2 Implicit Rule for Archive Member Targets		The implicit rule for archive member targets.
11.3 Dangers When Using Archives		Dangers to watch out for when using archives.
11.4 Suffix Rules for Archive Files		You can write a special kind of suffix rule for updating archives.

Implicit Rule for Archive Member Targets

11.2.1 Updating Archive Symbol Directories

How to update archive symbol directories.

Makefile Conventions

14.1 General Conventions for Makefiles
14.2 Utilities in Makefiles
14.3 Variables for Specifying Commands
14.4 Variables for Installation Directories
14.5 Standard Targets for Users
14.6 Install Command Categories		Three categories of commands in the `install'

Copying This Manual