The operating systems handbook : UNIX, OpenVMS, OS/400, VM, and MVS.

This book shows you the following, for all five operating systems:
History of the operating system
Starting and ending a session
Filenames
How files are organized, and how to navigate
Available on-line help
Creating, copying, renaming, and deleting files
Using the text editor
Printing text files
Creating and running command files
Sending and receiving mail
A sample session
New computer science student? You'll probably need to learn UNIX in a hurry.
Graduating student? Take a look at those want ads. Big money employers have big metal rigs. If they're looking for UNIX programmers, the UNIX programmer who is comfortable with their big rigs will have a big advantage over some kid who only knows UNIX, Windows, and the Mac.
Think some of these operating systems are dinosaurs? Well, if you're right, who's going to port the applications away from them? People who know how to log on and get at and manipulate the files making up those applications, that's who. And then there are the shops repositioning their big rigs to be database servers--there's a lot of client/server work for people who can deal with clients and servers!