A command line tool installed as a core components of Spring Roo, which generates and synchronizes application code based on changes to classes or instructions fed to the shell itself.
The Shell provides a help and interactive hint engine, so you can ask questions about the various commands and get hints on the beginning steps to configure a Roo project.
The Roo Shell can be executed from the operating system command line, and in this mode, it uses the [TAB] character for command completion. For example, typing -- and hitting [TAB] when faced with a potential series of options will list them. You can type the first letters of an option, hit [TAB] again, and Roo will auto-complete them.
Roo can also be embedded in the SpringSourceToolSuite, which comes bundled with Spring Roo in the 2.3.3 Milestone releases. STS (the short name for SpringSourceToolSuite) can be downloaded for free, and can create Roo projects directly. You can open the roo Shell as a view (using the context menu on a project, and selecting Spring -> Open Roo Shell).
Here is a sample interaction with the Roo Shell:
(message with roo startup banner appears, then roo prompt)
(roo creates a Spring project, then returns with the roo prompt)
(roo adds artifacts to maven build, Spring connection pool, transaction support, JPA and more)
''(roo installs a JPA entity in the com.demo.rooapp.db.Customer package, sets the current JPA entity to Customer)
(roo adds a String field to the JPA entity Customer (being the current entity)