On Sat, 14 May 2016 21:27:17 +0200
<emninger@???> wrote:

> If you configure wpa_supplicant with ceni (which also does the job for
> wired connections, btw) then, the wifi connection on the next boot is
> started *BEFORE* the login screen.

If you don't need roaming, it's sufficient to have the following lines
into your /etc/network/interfaces

auto wlan0
iface wlan0 inet dhcp
    wpa-ssid    $SSID
    wpa-psk     $PASS

> should there be a service "wpa_supplicant" in /etc/init.d/ ?

This is not necessary, you can

auto wlan0
iface wlan0 inet dhcp
    wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

I never tried that, but for roaming you can do something like

auto wlan0
iface wlan0 inet dhcp
    wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf

Florian