1.1 What this book is

This book is a tutorial for Autoconf, Automake and Libtool, hereafter referred to as the GNU Autotools. The GNU manuals that accompany each tools adequately document each tool in isolation. Until now, there has not been a guide that has described how these tools work together.

As these tools have evolved over the years, design decisions have been made by contributors who clearly understand the associated problems, but little documentation exists that captures why things are the way the are. By way of example, one might wonder why some Autoconf macros use shell constructs like:

if test "x$var" = xbar; then echo yes 1>&5 fi

instead of the simpler:

if [ $var = bar ]; then echo yes 1>&5 fi

Much of this reasoning is recorded in this book.