The most important thing about using Linux is the command. However, most people just use the desktop version of Ubuntu and just open the Terminal program when they need a command.
Command Line Working Group
Press [Ctrl]+[Alt]+[F1]to enter the first working group (tty1)
and so on, press [Ctrl]+[Alt]+[Fn]to enter the Nth working group (tty n)
The first to sixth workgroups are in command line mode. After entering, enter the user name + Enter, and then the password (not displayed) + Enter to log in; the seventh workgroup is X Window (ie GUI workgroup).
If it is started in command line mode, that is, tty7 does not have X Window, you can log in in the workgroup from tty1 to tty6 and enter to startxstart X Window.
Note: It is recommended to use a non-root normal user when logging in, because root symbolizes the highest privilege in Linux, and it is likely
rm -r *to break the system with a wrong command (eg, don't try, this will delete the entire system). It's a good habit to register a normal user for normal use, and operate viasu rootorsudocommand when necessary.