Configure script: Difference between revisions

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

{{Context|date=October 2009}} {{Unreferenced|date=March 2007}}

{{Lowercase title}}

[[Image:Autoconf.svg|thumb|300px|Flow diagram including configure, [[autoconf]] and [[automake]], three tools in the GNU build system]]

When installing a package on a [[Unix]] or [[Unix-like]] environment, a '''configure script''' is a [[shell script]] that generates [[software build|build]] configuration files for a [[codebase]] to facilitate cross-platform support. It generates files tailoring for the host system {{endash}} the environment on which the codebase is built and run.

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.

'''Configure scripts''' are an automated method of modifying [[source code]] before compilation in order to produce code tailored to the system on which a binary [[executable]] is to be compiled and run. Configure scripts are typically run immediately before compilation on the machine on which the software is to be used.

Obtaining a software package as [[source code]] and [[compiler|compiling]] it locally is a common scenario on [[Unix]] and [[Unix-like]] environments. Typically, this process involves the following steps:

Configure scripts are generated by the [[Autotools]] suite of build management tools. These scripts query the system on which they run for environment settings, platform architecture, and the existence and ___location of required build and runtime dependencies. They then use the gathered [[Intelligence (information gathering)|information]] to process and fill out templates, customarily ending in <code>.in</code>. After successful completion, it is common for configure scripts to print a report to the developer invoking them.

# Generate build configuration files

Because of the platform independence and broad developer experience with the configure script interface, many popular pieces of [[free software]] and [[proprietary software]] use this system during their system detection and [[makefile]] generation phase. After configure scripts have been created, building software that makes use of them is as simple as

# Build the code

# Install the result to an accessible ___location

A configure script accomplishes the first step by generating a [[makefile]] that is configured for the host system. This includes using the [[Library (computer science)|libraries]] of the host as required by the codebase.

<code>./configure && make && make install </code>

== Dependency checkingUse ==

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

After navigating a command-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>

[[Category:Compiling tools]]

[[Category:Unix software]]

[[Category:Build automation|configure]]

<syntaxhighlight lang="sh">

./configure

make

make install

</syntaxhighlight>

For the Autotools, the configure script logs status and errors to file ''config.log'', and the command <code>./configure --help</code> outputs command line help information.

{{compu-prog-stub}}

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

[[pl:Configure]]

[[pt:Configure]]

== Generating ==

[[tr:Configure]]

Autotools simplifies some of the challenges 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> to be read by <code>configure</code> during the installation phase.

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's 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 tools have been developed to automate the creation of configure scripts, of which the most common is [[Autoconf]].

== References ==

{{Reflist}}

[[Category:Compiling tools]]

[[Category:Linux configuration utilities]]

[[Category:Unix softwareprogramming tools]]

[[Category:Build automation|configure]]