Ant

Description:

Ant replaces Make as the tool of choice to build, test, deploy, and manage Java-based projects. Conceived as an alternative to other tools whose limitations made it more difficult than necessary to develop software across multiple platforms, the remarkably useful Ant does away with shell-based commands and "inherently evil" makefiles (along with their dreaded tab problems).

Ant is extended using Java classes instead of shell-based commands. Configuration files are XML-based, calling out a target tree where various tasks get executed. Each task is run by an object that implements a particular Task interface. We hear you out there! What of the expressive power, you say, that is inherent in being able to construct a shell command such as find . -name foo -exec rm {}? You're right, some of that power has been removed in favor of the ability to go cross platform, to work anywhere and everywhere. However, if you simply must execute a shell command, Ant still has an exec task, that allows different commands to be executed based on the Operating System.

If you use no other open source tools, use Ant! We've used it on dozens of projects and can't live without it.