Among other things, Unix system management is somewhat of a black art best left to those so inclined. While Unix vendors are creating interfaces which respond to the need for friendlier system management tools, as a consequence of its power and vitality, Unix is still a complicated and ever-changing system. There are several books discussing systems management listed in the Bibliography, and we won't try to summarize them here. Instead, we'll look at a few commands which check the health of your system and make sensible reports. You probably should use these commands regularly since they are the Unix equivalent of checking the oil in your car. Even if you are not having problems, running these commands is a way to teach yourself the normal state of your machine and of discovering problems in the making. Furthermore, we suggest keeping print outs of the system's response to these commands in the system notebook for reference.