Renaming ORACLE datafiles

1.Take the tablespace where the datafile resides offline.
i.e.: alter tablespace ... offline;

2. Rename the datafile (at the OS level)
i.e.: mv old_file new_file

3. Rename the datafile at the database level
i.e.: alter database rename file 'old_file' to 'new_file';

4. Bring the tablesace online.
i.e.: alter tablepsace ... online