Why do I get error "[unixODBC][Easysoft][Oracle]Could not open libclntsh.so.8.0 or libclntsh.so.9.0 error: ELFCLASS64"?

The usual reason for this is your Oracle client libraries are 64-bit. If this is the case, you should have a directory named lib32 in ORACLE_HOME. Rename the lib32 directory to lib. (Rename your existing lib directory first.)