The linux Command Line has six running levels to start the Linux operating system: 0: stopped, and the machine is disabled (do not set initdefault to 0 ). 1: single-user mode, like Windows 9x security mode. 2: multiple users, but not NFS. Www.2cto.com 3: full multi-user mode, standard running level (we set the command line to use it for startup ). 4: Reserved. It is generally not used. In some special cases, you can use it to do something. For example, you can switch to this mode to make some settings when the battery of your laptop is exhausted. 5: X Window graph startup (default startup mode ). 6: restart. You can find the/etc/inittab file and change "id: 3: initdefault:" to "5: initdefault:" In the text line. Restart the file. Here we change the running level from the window mode of 5 to the command line mode of 3. Note that you must use the Administrator permission to change this file. You can also use telinit n to start the instance. Use startx to start the graphical environment.