root@beaglebone:~# wpa_supplicant -ddd
wpa_supplicant v0.7.3
Copyright (c) 2003-2010, Jouni Malinen <[email protected]> and contributors

This program is free software. You can distribute it and/or modify it
under the terms of the GNU General Public License version 2.

Alternatively, this software may be distributed under the terms of the
BSD license. See README and COPYING for more details.

usage:
  wpa_supplicant [-BddhKLqqstuvW] [-P<pid file>] [-g<global ctrl>] \
        -i<ifname> -c<config file> [-C<ctrl>] [-D<driver>] [-p<driver_param>] \
        [-b<br_ifname>] [-f<debug file>] \
        [-o<override driver>] [-O<override ctrl>] \
        [-N -i<ifname> -c<conf> [-C<ctrl>] [-D<driver>] \
        [-p<driver_param>] [-b<br_ifname>] ...]

drivers:
  wext = Linux wireless extensions (generic)
  nl80211 = Linux nl80211/cfg80211
  hostap = Host AP driver (Intersil Prism2/2.5/3)
  wired = Wired Ethernet driver
options:
  -b = optional bridge interface name
  -B = run daemon in the background
  -c = Configuration file
  -C = ctrl_interface parameter (only used if -c is not)
  -i = interface name
  -d = increase debugging verbosity (-dd even more)
  -D = driver name (can be multiple drivers: nl80211,wext)
  -g = global ctrl_interface
  -K = include keys (passwords, etc.) in debug output
  -t = include timestamp in debug messages
  -h = show this help text
  -L = show license (GPL and BSD)
  -o = override driver parameter for new interfaces
  -O = override ctrl_interface parameter for new interfaces
  -p = driver parameters
  -P = PID file
  -q = decrease debugging verbosity (-qq even less)
  -u = enable DBus control interface
  -v = show version
  -W = wait for a control interface monitor before starting
  -N = start describing new interface
example:
  wpa_supplicant -Dwext -iwlan0 -c/etc/wpa_supplicant.conf