This is all controlled by /etc/issue
You can basically enter anything in there that you like, but there are preset variables that are mentioned at the end of the page that discuss this.
Some examples of /etc/issue:
Kernel \r on an \m
Ubuntu 16.04.6 LTS \n \l
You can also insert any of the characters below preceded by a blackslash \ and it will insert the relevant information.
b Insert the baudrate of the current line. d Insert the current date. s Insert the system name, the name of the operating system. l Insert the name of the current tty line. m Insert the architecture identifier of the machine, e.g., i686. n Insert the nodename of the machine, also known as the hostname. o Insert the domainname of the machine. r Insert the release number of the kernel, e.g., 126.96.36.199. t Insert the current time. u Insert the number of current users logged in. U Insert the string "1 user" or "
users" where is the number of current users logged in. v Insert the version of the OS, e.g., the build-date etc.
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