The script runGuiDemo.sh is probably outdated. It is using a "gui-demo" to set java classpath, which must have been renamed to "gui" in some release. So:

for i in ${ISPN_HOME}/modules/gui-demo/*.jar ; do
CP=${i}:${CP}
done

for i in ${ISPN_HOME}/modules/gui-demo/lib/*.jar ; do
CP=${i}:${CP}
done

Throws an exception:

Caused by: java.lang.ClassNotFoundException: org.infinispan.demo.InfinispanDemo
at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
Could not find the main class: org.infinispan.demo.InfinispanDemo. Program will exit.

Just update the command to:

for i in ${ISPN_HOME}/modules/gui/*.jar ; do
CP=${i}:${CP}
done

for i in ${ISPN_HOME}/modules/gui/lib/*.jar ; do
CP=${i}:${CP}
done