Linux Tty-init level 1-7

1. If init:0

The system shuts down automatically after a reboot.

2. If init:1

After rebooting the system into single-user mode, the default prompt is sh-3.00#, the result of input TTY is/dev/console, the result of input runlevel is 1 S, where 1 indicates that the running level of 1,s indicates that the running mode is single, that is, one-user mode.

3. If Init:2

After rebooting the system into multi-user mode and no network support, the default is a login interface, let you enter the user and password. The result of the input TTY is/dev/tty1, the TTY is the Virtual Console and can be converted between tty1 and tty6 by pressing the ALT+F1-F6 shortcut key. The result of input runlevel is n 2, where n indicates that the running mode is multi-user and 2 means that the run level is 2, that is, multi-user has no network support.

4. If Init:3

After rebooting the system into multi-user mode and network support, the default and Init:2 is also a login interface, enter the user and password, input TTY results are still/dev/tty1, input runlevel Get the result is n 3, where n indicates that the operating mode is multi-user, 3 indicates a run level of 3, which means that multiple users have network support, which is similar to Init:2.

5. If Init:4

Some materials or tutorials do not mention the 4 level of INIT, but in order to confirm that the operating level is changed to 4 after the restart, and 2, 3 are very similar, but RunLevel is n 4.

6. If Init:5

This is the installation of the Linux default into the GUI mode, that is, 3 input startx into the interface, multi-user and network full support. The result of the input TTY is/DEV/PST/1.

7. If Init:6

If set to Init:6, the system restarts continuously.

What if it's set to a different number? Like 7, 10, 100?

After that, I also did this test, set the Init value to 7, reboot and found that the system does not start, prompting

No more processes left in this runlevel

Changed to 8, 9 is the same, but changed to 10, then entered the Init:4 mode, TTY display as the default tty1. 100 as well.

Constantly changing the numbers, found that if it is related to 7, 8, 9 is unable to start, such as 17, 18, 177, 188 and so on.

Specific reasons do not understand.

Description

The TTY port connects directly to the stdin file descriptor, and you cannot transfer the display on the local TTY terminal over the network to the client,

The PTS virtual terminal is displayed by a PTMX char device that passes stdin to the client's PTS terminal.