This is a simple yet important process to do on ORACLE in case your disk runs out of space, lets say your $ORACLE_HOME disk area or partition ran out of space and you need to move the data files into /home/oradata which has a lot of free fresh space.

Step 1. Shutdown the database
./sqlplus /nolog
./connect / as sysdba
./shutdown immediate

Step 2. Move the data files physically
cp -R --force /u01/app/oracle/oradata/orcl/* /home/oradata

Step 3. Startup mount the database
./sqlplus /nolog
./connect / as sysdba
./startup mount

Step 4. Alter the database and specify the new location of EACH datafile
Run this command on sqlplus

alter database rename file
'/u01/app/oracle/oradata/orcl/users01.dbf' to
'/home/oradata/users01.dbf';
alter database rename file

Once you finish giving the location of all DATAFILES then shutdown immediate the database and make a STARTUP , which will load the database in normal mode.
Simple yet powerfull command.

Hope its usefull.
Felipe