Add a file named fluxbox.desktop to / usr / share / xsessions
[Desktop Entry]
Encoding=UTF-8
Type=XSession
Exec=/usr/bin/startfluxbox
TryExec=/usr/bin/startfluxbox
Name=fluxbox
Log out or reboot
In tty:
echo -e "#! /bin/bash\n\nexec /usr/bin/startfluxbox" > ~/.xinitrc
startx