- Reboot machine and press
<shift>to configure GRUB - Select the entry you normaly boot, e.g.
Ubuntuand press<e>to temporary modify the entry - Search the line which begins with
linux /boot/vmlinuz[...] - Remove everything and including the
ro, e.g.ro quiet splashorro maybe-ubiquity - Replace it with
rw init=/bin/bash - Press F10 to boot the system
- Use
passwdto change therootpassword