Oracle database spatial Finishing Experience _oracle

Recently because of the unit database hard disk space, finishing the time to check a lot of articles, also carried out a test, sorted out some experience for everyone's reference.
First, see an article on the internet, how to shrink undo table space, release over occupied space, with the instructions above to look at, found that our hard drive on the undo space also accounted for 2G, so think of this space to clear out to solve the immediate need, so immediately tested.
The test passed, but there is a problem, the above use of the drop tablespace undotbs1 including contents, instructions, not the undotbs1.dbf file also cleared away, the hard disk is still full. (later thought, can you use drop tablespace undotbs1 including contents and datafiles?) Simply delete the file on the hard drive directly. The article said to wait for the original undo table space all undo SEGMENT OFFLINE, this I do not know how to operate, also can not see the above instructions to see the results. But with the command check, make sure the Undo table space has been transferred to UNDOTBS2.
In order to delete the undo file, the test was carried out.
Selecct name from V$datafile; The undotbs1.dbf file is not already in the data file listed.
Stop the Oracle service and stop listening. Move the undotbs1.dbf file to another space. Open the Oracle service and turn on listening. Service is normal. Prove that the document can be deleted.