Ramprasad

Installing the GNU Software

Introduction

Autoconfiguring software is distributed with packaged source code distributions. These are big files with filenames of the form:

package-version.tar.gz

For example, the file `autoconf-2.13.tar.gz' contains version 2.13 of GNU Autoconf. We often call these files source distributions; sometimes we simply call them packages.

The steps for installing an autoconfiguring source code distribution are simple, and if the distribution is not buggy, can be carried out without substantial user intervention.

1. First, you have to unpack the package to a directory:

   % gunzip foo-1.0.tar.gz
   % tar xf foo-1.0.tar

   This will create the directory `foo-1.0' which contains the package's source code and documentation. Look for the files `README' to see if there's anything that you should do next. The `README' file might suggest that you need to install other packages before installing this one, or it might suggest that you have to do unusual things to install this package. If the source distribution conforms to the GNU coding standards, you will find many other documentation files like `README'.
2. Configure the source code. Once upon a time that used to mean that you have to edit makefiles and header files. In the wonderful world of Autoconf, source distributions provide a `configure' script that will do that for you automatically. To run the script type:

   % ./configure

3. Now you can compile the source code. Type:

   % cd foo-1.0 % make

   and if the program is big, you can make some coffee. After the program compiles, you can run its regression test-suite, if it has one, by typing

   % make check

4. If everything is okay, you can install the compiled distribution with:

   % su
   # make install

The `make' program launches the shell commands necessary for compiling, testing and installing the package from source code. However, `make' has no knowledge of what it is really doing. It takes its orders from makefiles, files called `Makefile' that have to be present in every subdirectory of your source code directory tree. From the installer perspective, the makefiles define a set of targets that correspond to things that the installer wants to do. The default target is always compiling the source code, which is what gets invoked when you simply run make. Other targets, such as `install', `check' need to be mentioned explicitly. Because `make' takes its orders from the makefile in the current directory, it is important to run it from the correct directory.

The `configure' program is a shell script that probes your system through a set of tests to determine things that it needs to know, and then uses the results to generate `Makefile' files from templates stored in files called `Makefile.in'. In the early days of the GNU project, developers used to write `configure' scripts by hand. Now, no-one ever does that any more. Now, `configure' scripts are automatically generated by GNU Autoconf from an input file `configure.in'. GNU Autoconf is part of the GNU build system.

As it turns out, you don't have to write the `Makefile.in' templates by hand either. Instead you can use another program, GNU Automake, to generate `Makefile.in' templates from higher-level descriptions stored in files called `Makefile.am'. In these files you describe what is being created by your source code, and Automake computes the makefile targets for compiling, installing and uninstalling it. Automake also computes targets for compiling and running test suites, and targets for recursively calling make in subdirectories.

Last modified: 12/02/2009

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