First let me tell you some things that aren't really technical. They are quite important to know though and might save you at times.
All command line examples in this document are preceded with either a dollar or a rhomb sign. You can find this style throughout all Unix literature.
If you see a dollar sign, this is input you can (or should, see section No experiments as root) do as normal user. For example listing the current directory isn't something you must be root for:
$ ls |
A rhomb sign indicates that this command should be executed as root. This is especially common for administrative tasks for example adding a user.
# adduser |
If you're trying out something new, don't do it as root! You can create a new account specifically for testing purposes and then `su' to it. So if you do something wrong, you only trash the home directory of that user. If you do the same thing as root you might damage the whole system. If you have already created an account for you, you better use this one than creating a new one specifically for testing.
A Linux system usually comes with very good documentation. Most of it is accessible via the two commands man and info. In it's minimal form, man accepts a command, system function, etc. as parameter. This displays the help page with that name. For example
$ man bash |
provides you with a very long help document about the bash.
This file is displayed with your standard pager. Usually this is less or more. Both have the possibility to search for a text. Press slash on your keyboard, type the search term and then hit enter. To continue the search, just hit `n'.
There is a quite practical command line option to man.
$ man -k usage |
prints all man pages that have the word “usage” in the title. I used to use the command above quite often, because I always forgot the name of the command `df', but I knew that it reports the disk usage.
info is similar to man. The major difference is, that info supports hyperlinking while man is just a flat file.
Additionally it supports more features to find what you are looking for. After pressing `i' you are asked for an index term. For example after issuing
info bash |
In Unix literature you often find references to man pages. This is usually noted with the command name and a number in braces. For example bash(1). This means that you should look up the bash man page in section one. Use the command
$ man 1 bash |
to do that.
Usually you can ignore the number and just enter man followed by the name of the page. Entering the section number avoids ambiguity, because a man page with the same name can be available in different sections. See man(1) for an overview of the available sections.