How to increase diskspace for dev/sda2 Ubuntu

Hi, I have full dev/sda2, need to wrote commands to extend space of tis dev. I´m using Ubuntu 18.04 server. Filesystem Size Used Avail Use% Mounted on udev 3.9G 0 3.9G 0% /dev tmpfs 788M 19M 770M 3% /run /dev/sda2 20G 20G 0 100% / tmpfs 3.9G 0 3.9G 0% /dev/shm tmpfs 5.0M 0 5.0M 0% /run/lock tmpfs 3.9G 0 3.9G 0% /sys/fs/cgroup /dev/sda3 1.8T 555M 1.7T 1% /home /dev/sda1 487M 79M 379M 18% /boot tmpfs 788M 0 788M 0% /run/user/0