Make

• What are Makefile.am and Makefile.in?

Purpose of a makefile and how does makefile.am differ

This section is llm-generated by Phind

A Makefile is a file that contains a set of directives used by a make build automation tool to generate a target/goal. The main purpose of a Makefile is to simplify the build process of a software project. It allows developers to specify how to derive the target program from the source files, and in what order the files should be processed Source 2, Source 5.

A Makefile contains rules, which are the instructions for building the target. Each rule has a target, prerequisites, and a recipe. The target is the file to be generated, the prerequisites are the files that the target depends on, and the recipe is the series of commands that make will execute to generate the target Source 5, Source 6.

For example, a simple Makefile might look like this:

CFLAGS = -Wall -Wextra
CC = gcc
VPATH = src
 
make_tutorial : main.o calculator.o greeter.o
       $(CC) $(CFLAGS) $? -o $@
 
main.o : main.c
       $(CC) $(CFLAGS) -c $? -o $@
 
calculator.o : calculator.c
       $(CC) $(CFLAGS) -c $? -o $@
 
greeter.o : greeter.c
       $(CC) $(CFLAGS) -c $? -o $@

This Makefile specifies how to compile and link several C source files into a single executable Source 5.

On the other hand, a Makefile.am is a script designed to feed Autoconf to provide dependency information as a higher-level yet more readable abstraction. Autoconf uses this information to generate Makefile.in files, which contain scripts and information for the actual configuration process. This combination helps us save precious time as we don’t need to dig through the pile of configuration mayhem anymore Source 1.

In summary, the main difference between a Makefile and a Makefile.am is that the former is used by the make tool to build a software project, while the latter is used by the automake tool to generate a Makefile.in file, which is then used by autoconf to generate a Makefile.