Simple question about wpa_supplicant conf file.

[Soft Ergate]

What is the meaning of "ctrl_interface=/var/run/wpa_supplicant"?
Does that indicate the path of control program(wpa_cli)? if so, how does 
wpa_supplicant use the path?
In fact, the program "wpa_cli" is always in the same directory with 
wpa_supplicant.

_________________________________________________________________
???? MSN Explorer:   http://explorer.msn.com/lccn/