Linux use visa？

I now have to use visa on linux(ubuntu) system, but can not find recource, it will print "num is 0" in below code, but lsusb have the device(keithley 2230)

how to use visa to control device on linux system? thanks!

zewen@zewen-OptiPlex-7040:~$ lsusb 
Bus 001 Device 002: ID 248a:5320  
Bus 001 Device 015: ID 05e6:2230 Keithley Instruments 
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

status = viOpenDefaultRM(&defaultRM);

if(status < VI_SUCCESS)
	printf("viopendefaultrm error!\n");
else 
	printf("viopendefaultrm success!\n"); //print this line

ErrorStatus = viFindRsrc(defaultRM, "?*", &fList, &numInstrs, desc);

if(numInstrs == 0)
	printf("num is 0 \n");// will print this line