Hi,
I want to learn more about UNIX shell commands, so I am searching a good book, that explains the most needed shell commands and how to get better on the terminal in general.
I am using Ubuntu(Debian).
The book should not have more than ~250 pages.
I am neither a noob nor a pro using the terminal.
Best regards
The O'Reilly book 'Linux in a nutshell' isn't bad but already beyond 250 pages -- which is not a realistic constraint.
I really really really like Unix Power Tools
It is big, far more than 250 pages, but you don't have to read everything, you can jump between sections easily to learn progressively. In fact the Author advise to jump between section :)
Learn from the guys who invented it. Pretty old and some of the material is not so relevant today, but I suggest taking a look at The Unix Programming Environment anyway. Perhaps you can pick up a used copy somewhere - around $40 at Amazon seems a bit pricey.
357 pages according to Amazon. I don't have my copy within reach, but from memory I would have thought it also matches your criterion of ~250 pages.
My favorite:
My edition is significantly older than that, but still useful.
It definitely does not have every command or every permutation of the commands it does list. But it's organized to be practically useful, the explanations make sense, and it can often be funny. Somehow the humor and the witty sidebars have always helped me remember the terminal commands enough that with a little help from "man" this is the only book I've ever purchased.
I'd recommend searching around for an old edition. No reason to spend alot on the latest edition -- the most useful commands have not changed much in the last 10 years.