/etc/rc.local no longer automatically exists in many Linuxes. This was a script run at boot before any user logins, after setup. If your Linux distro uses ‘systemd’, a relatively new boot system, this may be your situation; but the functionality is still useful in many special circumstances. If it’s yours, create a file named /etc/systemd/system/rc-local.service containing the below, and a new bash script called /etc/rc.local will run just as desired! Do be sure to set your new /etc/rc.local as executable, or you will regret it :-)
/etc/systemd/system/rc-local.service [Unit] Description=/etc/rc.local Compatibility [Service] Type=oneshot ExecStart=/etc/rc.local TimeoutSec=0 StandardInput=tty RemainAfterExit=yes [Install] WantedBy=multi-user.target