Editing GNU Autotools (section)

== Usage ==

[[File:Autoconf-automake-process.svg|thumb|450px|right|Flow diagram of Autotools tools.]]

Autotools assists with sharing [[cross-platform]] 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 [[configure script|script]], named ''configure'', that has no dependencies other than a [[Bourne shell|Bourne-compatible]] [[Unix shells|shell]]. Autotools need not be available. The consumer runs <code>configure</code> which generates various files including a ''Makefile'' which the consumer uses by running <code>make</code>.<ref>{{cite web|url=https://www.gnu.org/software/automake/manual/html_node/GNU-Build-System.html |title=automake: GNU Build System |website=Gnu.org |date=2014-12-31 |access-date=2016-04-01}}</ref><ref>{{cite web|url=http://airs.com/ian/configure/configure_1.html#SEC5 |title=The GNU configure and build system - Introduction |website=Airs.com |date=1998-07-01 |access-date=2016-04-01}}</ref>

Autotools can be used both for building native programs on the build machine and also for [[cross-compiling]] to other architectures.<ref>{{cite web|url=http://sources.redhat.com/autobook/autobook/autobook_258.html |title=Cross Compilation with GNU Autotools |access-date=September 24, 2008 |url-status=dead |archive-url=https://web.archive.org/web/20081013213002/http://sources.redhat.com/autobook/autobook/autobook_258.html |archive-date=October 13, 2008 }}</ref>

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]] 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 [[Unix-like]] 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 [[Unix-like]] [[compatibility layer]], though, allowing [[configure (computing)|configure]] scripts to run.  Cygwin also provides the [[GNU Compiler Collection]], [[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 (operating system)|fork system call]], may execute configure scripts considerably slower than on [[Linux]].<ref>{{cite web|url=http://cygwin.com/ml/cygwin/2005-04/msg00703.html |title=Robert Ögren - Slow shell script execution on Cygwin |website=Cygwin.com |access-date=2016-04-01}}</ref>