Some Other Useful Commands who Shows who's signed on to this machine. Use this to change your password. See section 3.1 for tips on choosing a secure password. Tells you how much file space you're using and how close you are to running over your quota.
Most systems implement disk quotas to prevent people from filling up the disks.
This is pretty much the only on-line help you get for most Unix commands, and the documentation is pretty terse, but it's there. The main problem with man pages is that they tend to present all the information about a command in some non-tutorial fashion. All the information is there, but you may not know where to find it. Fortunately, tutorial guides are available for some of the more complex programs including the C shell. This is a variant of man that tells you what manual pages reference the given keyword.