The graphics mode allows the use of software with a mouse, buttons and windows. Sometimes, as in all systems, it may be that the GUI will not boot and you must then try to fix it in text mode.
To see the text mode Linux, do a CTRL + ALT + F1. That's what we have if the GUI does not start. This may be as basic interface, but you better learn how to use it if necessary. This tutorial, not exhaustive, is designed to enable you to get by.
The basic commands
Here is a list of basic Linux commands.
The text editor
Linux is made of files, that we must often edit. If Kwrite and Gedit are of good practicein graphical mode, they will be of no help in a terminal.
There are console text editors like vi or emacs.
Command: vi /path/to/file
Save: type: w
leave the editor: type: q
For example, if vi is missing, you can install it using the same command line with the usual package manager: aptitude or apt-get under Debian systems and derivatives or Yum in Red Hat and derivatives.
Accessing the web
The websites are full of information. And even without Firefox or Konqueror, you can access it! Just take a text browser. Browsing is not as soft as usual and there are no pictures or colors, but it can be useful.
Lynx is an example of text-based browser.
to run, type lynx" or "lynx --display_charset=utf-8".
Then look for a web address with the key: "g".
If the GUI does not respond, we can try to kill the process in text mode with the task manager: "top" or "htop" which is simpler and making use of colors(16 colors).
It uses the keys "up" and "low" to select the process, then press "F9" to kill process.