wpa_supplicant is described as 'is designed to be a "daemon" program that runs in the background and acts as the backend component controlling the wireless connection'. There are seven alternatives to wpa_supplicant for Linux and Xfce. The best alternative is wicd, which is both free and Open Source. Other great apps like wpa_supplicant are NetworkManager (Free, Open Source), Ethtool (Free, Open Source), ceni (Free, Open Source) and iw (Free, Open Source).
iw is a new nl80211 based CLI configuration utility for wireless devices. It supports almost all new drivers that have been added to the kernel recently. It allows you to configure and show information about wireless networking.