i used web to setup the folder monitor
settng -> Data inputs » Files & directories »
but in the whitelist if i *.csv , it wont index even the file extension is csv.
i saw the doc is to edit inputs.conf
but in the system/local/inputs.conf i cannot find the folder path i setup in web.
so dont know where it is
The inputs.conf file will be saved under the app you were using when you selected Settings->Data Inputs. It's not likely to be in system/local. Try search/local and if it's not there, use your Linux-fu to find the inputs.conf file that changed most recently.
Once you find the file, post the relevant stanza here and we can help you fix it.