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<title>Apache Ant User Manual&mdash;Introduction</title>
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<h1 id="introduction">Introduction</h1>
<p>Apache Ant is a Java-based build tool. In theory, it is kind of like
<em>make</em>, without <em>make</em>'s wrinkles.</p>
<h3>Why?</h3>
<p>Why another build tool when there is already
<em>make</em>,
<em>gnumake</em>,
<em>nmake</em>,
<em>jam</em>,
and
others? Because all those tools have limitations that Ant's original author
couldn't live with when developing software across multiple platforms.
Make-like
tools are inherently shell-based: they evaluate a set of dependencies,
then execute commands not unlike what you would issue on a shell.
This means that you
can easily extend these tools by using or writing any program for the OS that
you are working on; however, this also means that you limit yourself to the OS,
or at least the OS type, such as Unix, that you are working on.</p>
<p>Makefiles are inherently evil as well. Anybody who has worked on them for any
time has run into the dreaded tab problem. &quot;Is my command not executing
because I have a space in front of my tab?!!&quot; said the original author of
Ant way too many times. Tools like Jam took care of this to a great degree, but
still have yet another format to use and remember.</p>
<p>Ant is different. Instead of a model where it is extended with shell-based
commands, Ant is extended using Java classes. Instead of writing shell commands,
the 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.</p>
<p>Granted, this removes some of the expressive power that is inherent in being
able to construct a shell command such as
<code>`find . -name foo -exec rm {}`</code>, but it
gives you the ability to be cross-platform&mdash;to work anywhere and
everywhere. And
hey, if you really need to execute a shell command, Ant has an
<code>&lt;exec&gt;</code> task that
allows different commands to be executed based on the OS it is executing
on.</p>

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