An Internationalized Software Project With Auto Tools
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Auto Tools Overview

This page briefly explains and summarizes the gnu auto tools and its value for users and developers.

Simple Approach: Manual Compilation

The most simple approach to compile a project is to write a short script, which just compiles all sources. The main disadvantage is, that everything is compiled. So if during the devlopement one file is changed, all are compiled, which is very time consuming.


Fortunately there exist a well established solution: 'make'. The make utility (or 'gmake' on some systems) reads a configuration file (usually calld 'Makefile') and executes it. The Makefile should contain dependency information between the source code files. So if a header file is changed, only those source files, which depend on the changed header file, are compiled. The bad side of this, that these dependency information either have to be maintained manually or by some automatic procession (which has to be implemented).

Furthermore, 'make' allows the user to specify one or more targets, which control the work to be done by 'make'. The names of these targets should be common among all projects, so that end users are quickly familar with it. Commonly used targets are: So writing a Makefile, which supports these targets can be a tough job. Furthermore, Makefiles usually work in a single directory, so that modularized sources require several Makefiles.

Another problem is, that several assumptions are platform dependent, like the name of the compiler to use (g++, or c++, or maybe cpp?) or the directories to search libraries in. These have to be found out automatically or specified by the user. Supporting this is beyond the scope of 'make'.


To solve this, the gnu build system requires an excutable called 'configure'. If executed, it analyzes the system to answer all these questions (which compiler? Where to find a liabrary?). User parameters are allowed to help answering this questions. Afterwards, the Makefile's are created, which reflect the result of the analysis.

To have 'configure' really portable it must be written in a language, available on all or nearly all target platforms without compilation. Shell script (sh) is a good canididate. Furthermore 'configure' usually needs some template files, to create the Makefiles from. These are usually called and have to be delivered as well.

So from the user perspective, software installation requires: The developer will mainly use the minimal rebuild property of 'make' and the other make target described above. Unfortunately the developer has to create the 'configure' script and the's. This task is simpified by the gnu auto tools. automake and autoconf are its most important.


Gnu autoconf (as well as automake) has to be installed on all developer computers (but not on the end user machines!). The developer writes a usually very small configuration file (called on, which contains the necessary actions written in a very short form (see the next chapters). Autoconf will read this file and create a configure script from it. While the configuration script is usually shorter than a kilo byte, the result script can be hundreds of kb large!


Gnu automake works similar. It requires one for each to create. Additionally it requires some lines in the or After running automake,'s are created, which support all make targets above, incremental builds and much more. Again typical's are quite short and contain usually lists of files to compile. The generated's are typical tens of kb in size.

Therefore the developers task is to create these (or .in) and the's. automake and autoconf create the 'configure' script and all's out of it. These are shipped to the user. User and developer have to run 'configure' to get the necesary Makefile's. These Makefiles also track changes in the's and (or .in) and trigger a rerun of automake, autoconf and 'configure', if necesary! So essentially the developer can change all the configuration and source code files. A simple 'make' does all necessary steps to reconfigure and recompile the project!

The remaining chapters mainly explain, how to write the and's
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Simple C Project Adding Auto Tool Support