The GNU Autotools, also known as the GNU Build System, is a suite of

build automation Build automation is the practice of building software systems in a relatively unattended fashion. The build is configured to run with minimized or no software developer interaction and without using a developer's personal computer. Build automati ...

tools A tool is an object that can extend an individual's ability to modify features of the surrounding environment or help them accomplish a particular task. Although many animals use simple tools, only human beings, whose use of stone tools dates ...

designed to support building

source code In computing, source code, or simply code or source, is a plain text computer program written in a programming language. A programmer writes the human readable source code to control the behavior of a computer. Since a computer, at base, only ...

and

packaging Packaging is the science, art and technology of enclosing or protecting products for distribution, storage, sale, and use. Packaging also refers to the process of designing, evaluating, and producing packages. Packaging can be described as a coo ...

the resulting binaries. It supports building a

codebase In software development, a codebase (or code base) is a collection of source code used to build a particular software system, application, or software component. Typically, a codebase includes only human-written source code system files; thu ...

for multiple target systems without customizing or modifying the

code In communications and information processing, code is a system of rules to convert information—such as a letter, word, sound, image, or gesture—into another form, sometimes shortened or secret, for communication through a communicati ...

. It is available on many

Linux distribution A Linux distribution, often abbreviated as distro, is an operating system that includes the Linux kernel for its kernel functionality. Although the name does not imply product distribution per se, a distro—if distributed on its own—is oft ...

s and

Unix-like A Unix-like (sometimes referred to as UN*X, *nix or *NIX) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Uni ...

environments. Autotools is part of the GNU toolchain and is widely used in many

free software Free software, libre software, libreware sometimes known as freedom-respecting software is computer software distributed open-source license, under terms that allow users to run the software for any purpose as well as to study, change, distribut ...

and

open source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use and view the source code, design documents, or content of the product. The open source model is a decentrali ...

packages. Its component tools are

, licensed under the

GNU General Public License The GNU General Public Licenses (GNU GPL or simply GPL) are a series of widely used free software licenses, or ''copyleft'' licenses, that guarantee end users the freedom to run, study, share, or modify the software. The GPL was the first ...

with special license exceptions permitting its use with

proprietary software Proprietary software is computer software, software that grants its creator, publisher, or other rightsholder or rightsholder partner a legal monopoly by modern copyright and intellectual property law to exclude the recipient from freely sharing t ...

Motivation

It can be difficult to make a software program portable. Compilers differ from system to system. Certain library functions are missing on some systems. Compiler files (such as C headers) may have different names. Shared libraries may be compiled and installed in different ways. One way to handle platform differences is to write conditionally compiled code (i.e. via #ifdef), but because of the wide variety of build environments, this approach quickly becomes unmanageable. Autotools is designed to address this problem more manageably.

Components

Autotools consists of the GNU utilities Autoconf, Automake, and Libtool. Other related tools include GNU make, GNU gettext,

pkg-config pkg-config is a software development tool that queries information about libraries from a local, file-based database for the purpose of building a codebase that depends on them. It allows for sharing a codebase in a cross-platform way by using ...

, and the

GNU Compiler Collection The GNU Compiler Collection (GCC) is a collection of compilers from the GNU Project that support various programming languages, Computer architecture, hardware architectures, and operating systems. The Free Software Foundation (FSF) distributes ...

(GCC).

Usage

Autotools assists with sharing

cross-platform Within computing, cross-platform software (also called multi-platform software, platform-agnostic software, or platform-independent software) is computer software that is designed to work in several Computing platform, computing platforms. Some ...

software with a relatively broad user community. It facilitates sharing the source code by providing relatively robust cross-platform build support so that consumers can build the software themselves. Generally, the source code is distributed with a script, named ''configure'', that has no dependencies other than a Bourne-compatible

shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses Science Biology * Seashell, a hard outer layer of a marine ani ...

. Autotools need not be available. The consumer runs configure which generates various files including a ''Makefile'' which the consumer uses by running make. Autotools can be used both for building native programs on the build machine and also for cross-compiling to other architectures. Cross-compiling software to run on a Windows host from a Linux or other Unix-like build system is also possible, using MinGW, however native compilation is often desirable on operating systems (such as the

Microsoft Windows Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sec ...

family of systems) that cannot run Bourne shell scripts on their own. This makes building such software on the Windows operating system a bit harder than on a

system which provides the Bourne shell as a standard component. One can install the Cygwin or MSYS system on top of Windows to provide a

compatibility layer In software engineering, a compatibility layer is an interface that allows binaries for a legacy or foreign system to run on a host system. This translates system calls for the foreign system into native system calls for the host system. With s ...

, though, allowing configure scripts to run. Cygwin also provides the

, GNU make, and other software that provides a nearly complete Unix-like system within Windows; MSYS also provides GNU make and other tools designed to work with the MinGW version of GCC. A consumer can re-generate the configure script which might be necessary if they amend the source code. In this case, they need to have Autotools installed. The autoconf-generated configure script can be slow because it executes programs such as a C compiler multiple times to test whether various libraries, header files, and language features are present. This particularly affects Cygwin, which, due to its lack of a native fork system call, may execute configure scripts considerably slower than on

Linux Linux ( ) is a family of open source Unix-like operating systems based on the Linux kernel, an kernel (operating system), operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically package manager, pac ...

Criticism

In his column for ''

ACM Queue ACM ''Queue'' (stylized ''acmqueue'') is a bimonthly computer magazine, targeted to software engineer Software engineering is a branch of both computer science and engineering focused on designing, developing, testing, and maintaining softwar ...

'',

FreeBSD FreeBSD is a free-software Unix-like operating system descended from the Berkeley Software Distribution (BSD). The first version was released in 1993 developed from 386BSD, one of the first fully functional and free Unix clones on affordable ...

developer Poul-Henning Kamp criticized the GNU Build System: Kamp sketches the history of the build system in the portability problems inherent in the multitude of 1980s Unix variants, and bemoans the need for such build systems to exist: Although critics of the Autotools frequently advocate for alternatives that provide greater simplicity to their users, some have argued that this is not necessarily a good thing. John Calcote, author of the ''Autotools, 2nd Edition: A Practitioner's Guide to GNU Autoconf, Automake, and Libtool'', opined:

References

External links