Classic Shell Scripting

Automating Software Builds

Because Unix runs on so many different platforms, it is common practice to build software packages from source code, rather than installing binary distributions. Large Unix sites often have multiple platforms, so their managers have the tedious job of installing packages on several systems. This is clearly a case for automation.

Many software developers now adopt software-packaging conventions developed within the GNU Project. Among them are:

• Packages that are distributed in compressed archive files named package-x.y.z.tar.gz (or package-x.y.z.tar.bz2) that unbundle into a directory named package-x.y.z.

• A top-level configure script, usually generated automatically by the GNU autoconf command from a list of rules in the configure.in or configure.ac file. Executing that script, sometimes with command-line options, produces a customized C/C++ header file, usually called config.h, a customized Makefile, derived from the template file Makefile.in, and sometimes, a few other files.

• A standard set of Makefile targets that is documented in The GNU Coding Standards, among them all (build everything), check (run validation tests), clean (remove unneeded intermediate files), distclean (restore the directory to its original distribution), and install (install all needed files on the local system).

• Installed files that reside in directories under a default tree defined by the variable prefix in the Makefile and is settable at configure time with the —prefix=dir command-line ...