kali@kali:~$ echo "deb http://http.kali.org/kali kali-rolling main non-free contrib" | sudo tee /etc/apt/sources.list
kali@kali:~$ echo "deb http://http.kali.org/kali kali-last-snapshot main non-free contrib" | sudo tee /etc/apt/sources.list
kali@kali:~$ echo "deb http://http.kali.org/kali kali-experimental main non-free contrib" | sudo tee /etc/apt/sources.list.d/kali-experimental.list
kali@kali:~$ echo "deb-src http://http.kali.org/kali kali-rolling main non-free contrib" | sudo tee -a /etc/apt/sources.list
kali@kali:~$ grep -v '#' /etc/apt/sources.list | sort -u
deb http://http.kali.org/kali kali-rolling main non-free contrib
kali@kali:~$