This tutorial is intended to give a general perspective on script virus in UNIX environments, as well as showing some examples of what can be done using the explained techniques.
There are many tutorials following the same topic, so this text is not new in that aspect, but I considered of interest writing it so I can give a more global focus to the topic, and show my examples in detail.
To finish this introduction I would like to epmhasize the work of SnakeByte and Gobleen Warrior in this field. I didn't know there were more people interested in this funny type of scripts :-)