Autotools

• https://opensource.com/article/19/7/introduction-gnu-autotools
• configure.ac
  • uses M4 language
  • AC_INIT
  • AC_OUTPUT
• Makefile.am
  • similar to Makefile

autoreconf -i
 
# delete old generated configuration files and overwrite them
# generate new files with verbose output
autoreconf -f -i -v
 
# Purge all generated files
autoreconf -p

• autogen.sh is custom script written by developer

#!/bin/sh
set -e
autoreconf -f --install --verbose

• Generate Makefile from
  • configure.ac
  • Makefile.am

./configure
 
# see all options
./configure --help
 
# change final installation directory
./configure --prefix=$HOME/.local
 
# machine where compilation will happen
./configure --build="aarch64-unknown-linux-gnu"
 
# --enable-<feature> / --disable-<feature>
./configure --disable-gui
 
# --with-<package> / --without-<package>
./configure --with-openssl
 
# pass compilation environment variables
./configure CFLAGS="-O3 -march=native" LDFLAGS="-L/usr/local/custom-lib"
 
# enable debugging
./configure --enable-debug

GNU Make

• Compile

make
 
# Run 3 jobs in parallel
make -j3

• Install to your system

sudo make install
 
# install to temporary destination
# see how the software will get installed
sudo make install DESTDIR=/tmp/pkg-root
 
# dry run
# prints all instructions for installation
make install -n
make install --just-print

• Uninstall if supported

sudo make uninstall

Makefile

• https://makefiletutorial.com/
• https://www.gnu.org/software/make/manual/html_node/Makefile-Contents.html
• It is a configuration file that instructs the make program exactly how to build the program
• consists of
  • variable definitions
    • srcdir, prefix, CC
  • explicit rules
    • targets, pre-requisites and the commands needed to create the target from components

    targets: prerequisites
    	command
    	command
    	command

  • implicit rules
    • .c.o: tells how to build .o from .c files
  • special target
    • .PHONY: tells which targets are phony
    • .SUFFIXES: tells which suffix based implicit rules are defined
  • directives
    • include, define, ifeq
• targets can be of two types
  • File target
    • examples: diction, diction.o, getopt.o, misc.o
  • Phony target
    • examples: install, clean, all, check, distclean, tar
• Sample Makefile

srcdir=		.
 
prefix=		/usr/local
 
CC= gcc
LDFLAGS= -g
 
.PHONY: all check install clean distclean tar
 
all: diction style all-po-no
 
diction:	diction.o sentence.o misc.o getopt.o getopt1.o
		$(CC) -o $@ $(LDFLAGS) diction.o sentence.o misc.o \
		getopt.o getopt1.o $(LIBS)
 
clean:
		rm -f *.out core *.o *.mo diction.html diction.info
 
diction.o:      diction.c config.h getopt.h misc.h sentence.h

Packaging

• Autotools do not support packaging
• OS tools are required to perform packaging
• The following steps are needed for debian packaging
  • Requirements:
    • Your source code (the application files)
    • A debian/ metadata folder (the configuration blueprints)
  • The Required Tools
    • build-essential: Installs compilers (gcc, make) to build the source code
    • dh-make: Generates the initial, blank debian/ metadata templates
    • debhelper: Provides the engine (dh) that converts the source and metadata into a finished .deb file