Linux aclocal Command with Practical Examples

Introduction

In this lab, we will explore the Linux aclocal command, which is a part of the Autoconf build automation tool. The aclocal command is used to generate the aclocal.m4 file, a crucial component in the Autoconf build process. We will learn how to use aclocal to create the aclocal.m4 file and integrate it with the Autoconf build process. This lab covers the introduction to the aclocal command, generating the aclocal.m4 file, and integrating aclocal with Autoconf.

Linux Commands Cheat Sheet

Skills Graph

Introduction to aclocal Command

In this step, we will explore the aclocal command, which is a part of the Autoconf build automation tool. The aclocal command is used to generate the aclocal.m4 file, which is a crucial component in the Autoconf build process.

The aclocal.m4 file contains macro definitions that are used by the autoconf command to generate the configure script. This script is responsible for configuring the build environment for a software project.

Let's start by running the aclocal command:

aclocal

Example output:

aclocal: creating ./aclocal.m4

As you can see, the aclocal command has created the aclocal.m4 file in the current directory. This file contains the necessary macro definitions for the Autoconf build process.

Now, let's take a closer look at the contents of the aclocal.m4 file:

cat aclocal.m4

Example output:

## generated automatically by aclocal 1.16.3 -*- Autoconf -*-

## Copyright (C) 1996-2020 Free Software Foundation, Inc.

## This file is free software; the Free Software Foundation
## gives unlimited permission to copy and/or distribute it,
## with or without modifications, as long as this notice is preserved.

## This program is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY, to the extent permitted by law; without
## even the implied warranty of MERCHANTABILITY or FITNESS FOR A
## PARTICULAR PURPOSE.

The aclocal.m4 file contains the necessary macro definitions for the Autoconf build process. These macros are used by the autoconf command to generate the configure script.

In the next step, we will learn how to integrate the aclocal.m4 file with the Autoconf build process.

Generating aclocal.m4 File

In this step, we will learn how to generate the aclocal.m4 file, which is a crucial component in the Autoconf build process.

The aclocal.m4 file contains macro definitions that are used by the autoconf command to generate the configure script. This script is responsible for configuring the build environment for a software project.

Let's start by creating a simple configure.ac file, which is the input file for the autoconf command:

nano configure.ac

Add the following content to the configure.ac file:

AC_INIT([my-project], [1.0], [[email protected]])
AC_CONFIG_SRCDIR([main.c])
AC_OUTPUT

Now, let's run the aclocal command to generate the aclocal.m4 file:

aclocal

Example output:

aclocal: creating ./aclocal.m4

As you can see, the aclocal command has created the aclocal.m4 file in the current directory. This file contains the necessary macro definitions for the Autoconf build process.

Now, let's take a closer look at the contents of the aclocal.m4 file:

cat aclocal.m4

Example output:

## generated automatically by aclocal 1.16.3 -*- Autoconf -*-

## Copyright (C) 1996-2020 Free Software Foundation, Inc.

## This file is free software; the Free Software Foundation
## gives unlimited permission to copy and/or distribute it,
## with or without modifications, as long as this notice is preserved.

## This program is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY, to the extent permitted by law; without
## even the implied warranty of MERCHANTABILITY or FITNESS FOR A
## PARTICULAR PURPOSE.

## AM_INIT_AUTOMAKE([foreign])
## AM_MAINTAINER_MODE([enable])

The aclocal.m4 file contains the necessary macro definitions for the Autoconf build process. These macros are used by the autoconf command to generate the configure script.

In the next step, we will learn how to integrate the aclocal.m4 file with the Autoconf build process.

Integrating aclocal with Autoconf

In this final step, we will learn how to integrate the aclocal.m4 file with the Autoconf build process.

First, let's run the autoconf command to generate the configure script:

autoconf

Example output:

configure.ac:1: installing './install-sh'
configure.ac:1: installing './missing'

As you can see, the autoconf command has generated the configure script, which is responsible for configuring the build environment for our software project.

Now, let's run the configure script to see how it interacts with the aclocal.m4 file:

./configure

Example output:

checking for a BSD-compatible install... /usr/bin/install -c
checking whether build environment is sane... yes
checking for a thread-safe mkdir -p... /bin/mkdir -p
checking for gawk... no
checking for mawk... mawk
checking whether make sets $(MAKE)... yes
checking whether to enable maintainer-specific portions of Makefiles... no
configure: creating ./config.status
config.status: creating Makefile

The configure script has used the macro definitions from the aclocal.m4 file to configure the build environment for our software project.

Finally, let's take a look at the contents of the configure script:

cat configure

Example output:

#! /bin/sh
## Guess values for system-dependent variables and create Makefiles.
## Generated by GNU Autoconf 2.71.

## This script was automatically generated from config.status. Run this script,
## or rerun config.status, to recreate the current configuration.

## This file is freely redistributable without restrictions.

## Copyright (C) 1992-1996, 1998-2021 Free Software Foundation, Inc.

## This configure script is free software; the Free Software Foundation
## gives unlimited permission to copy, distribute and modify it.

As you can see, the configure script contains the necessary logic to configure the build environment for our software project, based on the macro definitions in the aclocal.m4 file.

In summary, the aclocal command is used to generate the aclocal.m4 file, which is then integrated with the Autoconf build process through the autoconf command. This allows for a more robust and automated build process for our software project.

Summary

In this lab, we explored the aclocal command, which is a part of the Autoconf build automation tool. We learned that the aclocal command is used to generate the aclocal.m4 file, which contains macro definitions that are crucial for the Autoconf build process. The aclocal.m4 file is used by the autoconf command to generate the configure script, which is responsible for configuring the build environment for a software project. We also examined the contents of the aclocal.m4 file to understand the macro definitions it contains.

Next, we will learn how to integrate the aclocal.m4 file with the Autoconf build process.

Linux Commands Cheat Sheet