Configure script: Difference between revisions

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{{Short description|GNU Build SystemShell script for generating build configuration files on a Unix-like environment}}

{{Lowercase title}}

AsWhen generatedinstalling bya thepackage on a [[GNUUnix]] Buildor System[[Unix-like]] environment, a '''configure script''' is ana [[Bash (Unix shell)|Bash shellscript]] script that generates [[software build|build]] configuration files for a [[codebase]] to facilitate cross-platform support. It matchesgenerates thefiles [[Librarytailoring (computer science)|libraries]] onfor the build host computersystem with{{endash}} thosethe requiredenvironment byon which the codebase beforeis thebuilt [[sourceand code]] is [[compiler|compiled]]run.

[[Image:Autoconf-automake-process.svg|thumb|280px|Flow diagram including configure, [[autoconf]] and [[automake]], three tools in the GNU Build System]]

Even though there are no standards for such a script, the pattern is so ubiquitous that many developers are familiar with and even expect a script named ''configure'' that has this functionality. The script can be and originally was hand-coded. Today, multiple tools are available for generating a configure script based on special configuration files. One commonly used tool is [[Autotools]] which generates a [[Bash (Unix shell)|Bash]] script.

As generated by the [[GNU Build System]], a '''configure script''' is an [[Bash (Unix shell)|Bash shell]] script that generates [[software build|build]] configuration files for a [[codebase]] to facilitate cross-platform support. It matches the [[Library (computer science)|libraries]] on the build host computer with those required by the codebase before the [[source code]] is [[compiler|compiled]].

Obtaining softwarea directlysoftware frompackage theas [[source code]] and [[compiler|compiling]] it locally is a common procedurescenario on [[Unix]] and [[Unix-like]] environementsenvironments. ItTypically, this generallyprocess involves the following steps:

== Use ==

# Generate build configuration files

Obtaining software directly from the source code is a common procedure on [[Unix]] and [[Unix-like]] environements. It generally involves the following steps:

# CompileBuild the code

# Generate a [[makefile]]

# Compile the code

# Install the result to an accessible ___location

A configure script accomplishes the first step. The script automatesby generating a [[makefile]]; allowingthat foris tailoringconfigured it andfor the resultinghost softwaresystem. toThis includes using the system[[Library on(computer whichscience)|libraries]] itof isthe compiledhost andas run.required by the codebase.

== Use ==

After navigating a terminal to the directory that contains the source code, the following commands are typically executed:<ref>{{cite web |url=http://www.control-escape.com/linux/lx-swinstall-tar.html |title=Compiling Linux Software from Source Code |publisher=Control-Escape's Linux Help Engine |access-date=20 November 2010}}</ref>

After navigating a terminalcommand-line [[Shell (computing)|shell]] to the directory that contains the source code, the following commands are typically executed:<ref>{{cite web |url=http://www.control-escape.com/linux/lx-swinstall-tar.html |title=Compiling Linux Software from Source Code |publisher=Control-Escape's Linux Help Engine |access-date=20 November 2010}}</ref>

<syntaxhighlight lang="sh">

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AFor reportthe ofAutotools, the configurationconfigure operationscript canlogs bestatus foundand inerrors to file ''config.log''., Runningand the command <code>./configure --help</code> outputs command line syntaxhelp optionsinformation.

Often, a document with instructions is included with the codebase; often in a file named <code>INSTALL</code>. ThisIt can be helpful if <code>the configure</code> script fails.

== Generating ==

[[GNU Build System]] simplifies some of the the challenge of [[cross-platform software]] development.<ref>{{cite web |url=https://www.gnu.org/software/autoconf/ |title=Autoconf - GNU Project - Free Software Foundation (FSF) |publisher=GNU Operating System |access-date=20 November 2010}}</ref> These tools query the host system for environment settings, platform architecture, and the existence and ___location of required build and runtime dependencies. They store the gathered information in <code>configure.ac</code> or the now deprecated <code>configure.in</code> to be read by <code>configure</code> during the installation phase.

[[GNU Build System]]Autotools simplifies some of the the challengechallenges of [[cross-platform software]] development.<ref>{{cite web |url=https://www.gnu.org/software/autoconf/ |title=Autoconf - GNU Project - Free Software Foundation (FSF) |publisher=GNU Operating System |access-date=20 November 2010}}</ref> These tools query the host system for environment settings, platform architecture, and the existence and ___location of required build and runtime dependencies. They store the gathered information in <code>configure.ac</code> or the now deprecated <code>configure.in</code> to be read by <code>configure</code> during the installation phase.

== Dependency checking ==

In new development, library dependency checking hascan beenbe doneaccomplished in great part usingvia [[pkg-config]] via the [[M4 (computer language)|m4]] macro, PKG_CHECK_MODULES. Before pkg-config gained popularity, separate m4 macros were created to locate files known to be included in the distribution of libraries depended upon.

== History ==

The first program to come with a configure script was [[rn (newsreader)|rn]] by [[Larry Wall]] in 1984. The script was written by hand and produced a jocular running commentary when executed. It still survives as part of the build system of the '''trn''' program.<ref>{{cite web |url=https://github.com/acli/trn/blob/613a7e97aca06dd807fb225990fa804e8c744574/Configure|title= Configure script of trn |publisher=GitHub |access-date=10 December 2020}}</ref>

Since then, an ecosystem of programstools hashave grownbeen updeveloped to automate the creation of configure scripts as far as possible, of which the most common is the [[Autoconf|GNU Autoconf]] system.

== References ==