There are two types of processes in Linux:
- Foreground processes
- Background processes
A foreground process is a process that is attached to your terminal. You have to wait for a foreground process to finish before you can continue using your terminal.
On the other hand, a background process is a process that is not attached to your terminal, and so you can use your terminal while a background process is running.
The yes command outputs any string that follows it repeatedly until killed:
elliot@ubuntu-linux:~$ whatis yes
yes (1) - output a string repeatedly until killed
For example, to output the word hello repeatedly on your terminal, you can run the command:
elliot@ubuntu-linux:~$ yes hello
hello
hello
hello
hello
hello
hello
hello
hello
hello
hello
.
.
.
Notice that it will keep running, and you can't do anything else on your terminal; this is a prime example of a foreground process. To claim back your terminal, you need to kill...