When installing a package on a Unix or Unix-like environment, a configure script is a shell script that generates build configuration files for a codebase to facilitate cross-platform support. It generates files tailoring for the host system – 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 script.

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

A configure script accomplishes the first step by generating a makefile that is configured for the host system. This includes using the libraries of the host as required by the codebase.

After navigating a command-line shell to the directory that contains the source code, the following commands are typically executed:

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

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

Autotools simplifies some of the challenges of cross-platform software development. 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 configure.ac to be read by configure during the installation phase.