Debian 13 (Trixie)
nano /etc/apt/sources.list
deb http://deb.debian.org/debian trixie main contrib non-free non-free-firmware
deb-src http://deb.debian.org/debian trixie main contrib non-free non-free-firmware
deb http://deb.debian.org/debian trixie-updates main contrib non-free non-free-firmware
deb-src http://deb.debian.org/debian trixie-updates main contrib non-free non-free-firmware
deb http://security.debian.org/debian-security trixie-security main contrib non-free non-free-firmware
deb-src http://security.debian.org/debian-security trixie-security main contrib non-free non-free-firmware
Save and exit (Ctrl+O → Enter → Ctrl+X in nano).
