Oracle Client vs Oracle Instant Client on Linux!
If you only need to run SQLPlus, grab "Instant Client Package - Basic" and "Instant Client Package - SQL Plus: Additional libraries and executable for running SQL Plus with Instant Client" from http://www.oracle.com/technetwork/topics/linuxsoft-082809.html &amp; install them.

oci.dll is a windows file, so I have no idea what could be achieved by installing that on Linux.

unzip the files into a location of your choice &amp; set LD_LIBRARY_PATH and PATH to point to that directory. If you need any further help after that, edit your question.