How do I find the files those do not have an extension? For e.g. in the following screen, I will like to return the file sconnect and not .xls
-rwxr-xr-x 1 root root 12K Mar 7 19:29 ./Purchase_ORDER.xls
-rwxr-xr-x 1 root root 176 Mar 7 19:29 ./sconnect