Following are the steps to create a database manually :

Oracle Database must be installed.
Create pfile & start the instance. Copy pfile from another database & edit it.

cd $ORACLE_HOME/dbs
cp initprim.ora initdevdb.ora

3. Edit pfile with “ :%s/prim/devdb/g ” it will replace prim with devdb

4. Create respective directories as per file.

5. Set environmental variables to connect to new SID.

Export ORACLE_SID=devdb
Env|grep ORA