Project Jxta is a community-run attempt to build a utility application substrate for peer-to-peer applications. The initial reference implementation of Jxta includes a command-line shell that allows experimentation with the core Jxta platform without programming. This article takes us through a hands-on tour of the <a href="http://www-106.ibm.com/developerworks/java/library/j-p2pint2?open&l=766,t=grj,p=Jxta2">Jxta shell</a>. You'll explore its command set and extend its capability by writing your own custom commands using the Java programming language.