Ripper is located in /proj/nlp/tools/MachineLearning/ripper/ripper
The man pages for Ripper are available here (main and auxiliary)
You can read more about ripper in Cohen '95 and Cohen '96

To run Ripper, you should have the following files:

To run Ripper, execute the following command:
$ /proj/nlp/tools/MachineLearning/ripper/ripper bla

After training, Ripper will create file bla.hyp, which contains the classification rules.
The output of Ripper for our example is given below:

Final hypothesis is:
class2 :- right1_tag ~ NN (4/0).
default class1 (6/0).
=============================== summary ===============================
Train error rate: 0.00% +/- 0.00% (10 datapoints)
Test error rate: 0.00% +/- 0.00% (2 datapoints)
Hypothesis size: 1 rules, 2 conditions
Learning time: 0.00 sec