I'm confused with the terminology. What is the difference between shell, console, and terminal?
In the linux world they can all look the same from the point of view of the user at the keyboard. The differences are in how they interact with each other.
The shell is the program which actually processes commands and returns output. Most shells also manage foreground and background processes, command history and command line editing. These features (and many more) are standard in
bash, the most common shell in modern linux systems.
A terminal refers to a wrapper program which runs a shell. Decades ago, this was a physical device consisting of little more than a monitor and keyboard. As unix/linux systems added better multiprocessing and windowing systems, this terminal concept was abstracted into software. Now you have programs such as Gnome Terminal which launches a window in a Gnome windowing environment which will run a shell into which you can enter commands.
The console is a special sort of terminal. Historically, the console was a single keyboard and monitor plugged into a dedicated serial console port on a computer used for direct communication at a low level with the operating system. Modern linux systems provide virtual consoles. These are accessed through key combinations (e.g. Alt+F1 or Ctrl+Alt+F1; the function key numbers different consoles) which are handled at low levels of the linux operating system -- this means that there is no special service which needs to be installed and configured to run. Interacting with the console is also done using a shell program.
A shell is a program that puts up a prompt and waits for you to type commands. It executes them and then prints another prompt. So, like CMD in Windows, or Bash in Unix. It can run in a terminal or on the console.
A console was originally a physical thing, a control panel. In computing terms it usually means the display that you see before the GUI starts up or after it finishes; you can sometimes switch to displaying it instead of the GUI. It's the place where the operating system prints error messages. On a multi-user computer, it's the display that's actually attached to the computer. Just to confuse you, on Windows it can also mean a window with a command shell in it, i.e. a terminal.
A terminal was also originally hardware, used to communicate with a computer. Nowadays it usually refers to a window with a command line (shell), which might appear in a GUI window or instead of a GUI.
For beginner beginners
For a more detailed description: https://askubuntu.com/a/506628/130518
- terminal = text input/output environment
- console = physical terminal (something you can actually physically touch)
- shell = command line interpreter
I will be describing the most normal use case for this in the following text.
A terminal uses a shell. A shell can run without a terminal.
To relate to everyday items:
- Terminal -> TV screen in your home
- Shell -> Program that is running on the TV screen
Another way of looking at it: Your ears (input) and mouth (output) are the terminals for sound. Your brain is the interpreter of those sounds using a specific shell (processing).
The terminal is for us humans, so we can read and write to/from the shell. Shells can run in background processes that do not require human interaction e.g. cron job, and therefore do not require a terminal.
Few examples of terminals that exist:
- Command prompt
Few examples of shells that exist:
- sh (Bourne shell)
- PowerShell [windows]
- zsh (Z shell)
I've only written how these two normally work, there are other ways they work, but that is for a more advanced user.
A Terminal is a text-based interface (possibly to a shell)
The difference between console and shell is one I don't yet grasp, but I can tell you how a terminal is different from a shell.
The terminal is (according to Wikipedia) "a serial computer interface for text entry and display. Information is presented as an array of pre-selected formed characters".
You can use a terminal to interact with a shell, but you can also use it to interact with a text-based GUI, sometimes called a Terminal User Interface. For example:
- Vim has GUI elements including line numbers and named tabs
- Nano has GUI elements including a help menu of commands
- Tmux has GUI elements including a status bar and dividing lines between panes
- Minicom has GUI elements including menus and a status bar
In each case, the GUI elements are "drawn" with text rather than pixels.
Think to another context, that is development.
Even if you don't have a very deep knowledge of development, you probably know the basics, that is: you edit a program, you submit it to a compiler or to an interpreter that builds a compiled application.
The console is like the editor of your program; it helps you in writing but it doesn't really execute anything: when you have finished you send it to the compiler for that.
You can use your preferred editor, vim, gedit, emacs, notepad++, Netbeans, eclise etc.etc but at the end they are just different tools: if you write the same program the output will be the same.
In this metaphor, the shell is the compiler. The commands that are entered into the terminal, are sent to the shell that interprets them and executes them immediately.
So, while terminals are just front-ends for the shell, the shell contains the actual language, as happens for the compiler.
Obviously a terminal is not exactly a text editor, mainly because it doesn't produce a file but sends text to the underlying shell and retrieves output from it.
And the shell is not a compiler, in fact it interprets your command and executes it immediately instead of building an executable.
Even whit this big difference, i find this metaphor to help a lot in understanding this idea.
There really isn't much difference. Way back when the "shell" was a program, the "terminal" was a frontend wrapper to this program, and the "console" was the physical connection to the computer (keyboard / screen).
There is a difference depending on what OS you're running. The "standard" shell is BASH, which is normally available on all flavors of Linux / Unix. Windows uses an entirely different shell.