what is linux console

The Linux console is a terminal device or software that displays Linux system messages. By default, all virtual terminals in Linux are consoles and can display system messages; and those programs specifically designed to simulate terminal devices, such as "gnome-terminal", "mlterm" and other software, can also be called consoles.

#The operating environment of this tutorial: linux5.9.8 system, Dell G3 computer.

Terminal

Definition of terminal

(1) What is a terminal?

The terminal is a set of equipment that processes the input and output of the computer host. It is used to display the output of the host's operations and accept the input required by the host. Typical terminals include monitor keyboard kits, printer typewriter kits, etc.

(2) The essence of terminal.

In fact, it is basically just one sentence. It is enough to be able to accept input and display output. No matter what era it is, the terminal always plays the role of human-computer interface. The so-called Terminal is the edge of the machine. !

As long as it can provide input and output functions to the computer, it is a terminal, regardless of its location

Classification of terminals

• Local terminal

  Use VGA to connect the host and monitor, and use PS/2 or USB to connect the host and keyboard. Such a monitor/keyboard combination is a local terminal.

• Remote terminal connected by serial port

  Connect the host to another host with a monitor and keyboard through the serial port cable, and run a terminal simulation program, such as "Windows HyperTerminal" to lend the monitor and keyboard of this host to the host at the opposite end of the serial port.

• Remote terminal carried by TCP/IP

  Similar to Telnet, SSH.

The first two categories are also called "physical terminals", and the latter one is called "pseudo terminals"

Let's talk about these categories first. Bar. It can be seen that among the above three categories, the first two categories are directly associated with physical devices locally, such as VGA port, PS/2 port, serial port, etc. This kind of terminal is called a physical terminal, while the third category There is no physical device associated with it locally. Note that the physical network card should not be regarded as the physical device associated with the terminal. It is only the physical device associated with the tunnel. The physical network cards here can be replaced by trucks. They are not directly related to the terminal, so this Terminals whose classes are not directly associated with physical devices are called pseudo-terminals.

Console Console

What is the console

The terminal that displays system messages is called Console, by default all virtual terminals in Linux are consoles and can display system messages.

In addition, for those programs specifically used to simulate terminal devices, we can also call them consoles. Software such as gnome-terminal, urxvt, mlterm, xterm, etc. can all be called consoles.

Summary: The console is a special case of the terminal, a true subset of the terminal, it is a virtual terminal,

The difference between the terminal and the console

Physical terminal: The collective name for the monitor, keyboard and mouse directly connected to the host. In actual rack-mounted server deployment, multiple servers generally share a set of terminals, referred to as KVM (Keyboard keyboard, video display, mouse mouse)

Virtual terminal (tty): additional On top of the physical terminal, software is used to implement virtualization. CentOS enables 6 virtual terminals by default, which can be switched through shortcut keys. The switching method is: Ctrl-Alt-F[1--6], and the corresponding file is /dev/tty #.

You can view the current virtual terminal number through the tty command. tty is the abbreviation of teletype writer.

Pseudo terminal(pty): Two application scenarios,

(1) The first command line interface opened under the graphical interface, we often use Ctrl Alt T The one that is opened is actually a pseudo terminal

(2) The second command line interface that is opened remotely based on the ssh protocol or telnet protocol is the most commonly used method by operation and maintenance engineers to connect to the server. pts (pseudo-terminal slave) is the implementation method of pty.

Summarize three points of view:

(1) The console is a proper subset of the terminal;

(2) tty2-tty6, These five black interfaces are virtual terminals, which are real consoles. We call the five virtual terminals at this time consoles;

(3) Open under the desktop with Ctrl Alt T That thing is a pseudo terminal, and the pseudo terminal connected remotely through Telnet or ssh is also a pseudo terminal created;

Note: The difference between the console and the terminal has been completely diluted in Linux

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