"what has to happen before the kernel" is entered on a gnu/linux system? code example

Example 1: C language if age is over 20, but under 61, display the name and age, and tell the user he/she is an adult

Age is 25
Print user's name and age.
Printout would read "You are an adult!"

Example 2: What will be the result of the cp /etc/hosts . command?

What will be the result of the cp /etc/hosts .   command?