If you are running a Linux distribution that use Systemd, then you may find that your command in /etc/rc.local file would not run on system boot. The rc-local.service already exists in systemd and, if rc.local exists and is executable, it gets pulled automatically into multi-user.target.
You can check the status if you type the following command in terminal:
sudo systemctl status rc-local
First you need to create /etc/rc.local file, if it doesn't exists.
sudo nano /etc/rc.local
Make sure /etc/rc.local file is executable.
sudo chmod +x /etc/rc.local
Finally, enable the service on system boot.
sudo systemctl enable rc-local
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
# In order to enable or disable this script just change the execution
# By default this script does nothing.
<Add terminal commands here without sude>