Linux Basics/Terminals, command prompt, alias, history

What's a terminal?

 * Terminal = command prompt → shell = command-line interpreter
 * Text-mode, DOS-like
 * There are several terminals
 * Gnome-terminal, Xfce4-terminal, xterm, etc.
 * There are many shells (e.g. bash, fish, ksh, zsh etc.)
 * you can also customize the shells, for example this video on YouTube shows it: [GNOME 3.28 PowerLevel9k -  The Most Cool Linux Shell EVER! ]
 * commands can be executed
 * command list: https://ss64.com/bash/ (and also the Linux Basics/Basic commands chapter)
 * alias: we can shorten a complex command with an alias or we can create our own one.
 * Location of definition (in case of bash shell): ~/.bashrc
 * Global aliases: /etc/bashrc

History

 * It can be recalled by pressing up and down arrows on keyboard
 * you can switch tabs on terminal by pressing ctrl+page up or ctrl+page down
 * ~/.bash_history shows the commands before login

Environment variables
Environment variables: it stores information of the operating system or programs. Environment variables get set automatically after startup. For example, PATH environment variable tells the shell where to search the executable files.


 * Printing them to terminal: ,
 * but particular environment variables can be displayed too:
 * to set up an environment variable:
 * to delete an environment variable:
 * displaying a particular one(same as printenv basically):
 * to have the setting in the system permanently:
 * we can create an own command under  folder, but it works only if we added the folder to PATH environment variable:
 * , and to make it permanent in .bashrc:

Thottee explained it on his website in more detail that what we do exactly (his website is in hungarian so you may need to translate it with a translator program: http://linuxkezdoknek.hu/articles.php?article_id=33 (the article's second half)

Help



 * help for using a command:
 * command for the manual (detailed help): ,
 * usage: