APEX installation on Linux - Step by Step
Here the step by stepforAPEXinstallation on Linux. 
You can download the latestApexversion from: http://www.oracle.com/technetwork/developer-tools/apex/downloads/index.html

 1. Copy the apex_4.2.2_en.zip to /home/oracle
 cp apex_4.2.2_en.zip /home/oracle

  2. Extract apex_4.2.2_en.zip :  cd /home/oracle; unzip apex_4.2.2_en.zip;cd /home/oracle/apex 

3. Create a new tablespace for Apex objects:
Sqlplus /nologs 
create TABLESPACE APEX   
 DATAFILE '/full_path_for_data_directory/apex01.dbf'     SIZE 1000M     AUTOEXTEND ON     NEXT 100M     MAXSIZE 8000M;

  4. Start APEX installation: sqlplus sys as sysdba
 @apexins.sql APEX APEX TEMP /i/ 

 5. Change ADMIN account password:
sqlplus sys as sysdba
@apxchpwd.sql
 *** The password mst contait least one punctuation character: (!”#$%&()“*+,-/:;?_).

 6. Run the Embedded @apex_epg_config.sql  /home/oracle(full path)

Update the APEX images with those from the new release:
 sqlplus sys as svadba
 @apxldimg.sql /home/oracle (full path)

8. Make sure that the following accounts are unlocked and not expired:
 If EXPIRED - Change password for following users : ANONYMOUS,XDB,APEX_PUBLIC_USER,FLOWS_FILES,APEX_040200. IF LOCKED - Unlock: ALTER USER ANONYMOUS ACCOUNT UNLOCK; ALTER USER XDB ACCOUNT UNLOCK; ALTER USER APEX_PUBLIC_USER ACCOUNT UNLOCK; ALTER USER FLOWS_FILES ACCOUNT UNLOCK; ALTER USER APEX_040200 ACCOUNT UNLOCK;

 9. Enable network services (ACL) and XML DB HTTP server:
sqlplus sys as sysdba
exec dbms_xdb.sethttpport(8080);
Verify the port:
SELECT DBMS_XDB.GETHTTPPORT FROM DUAL;

 10. Enable remote HTTP connections: sqlplus sys as sysdba
 exec dbms_xdb.setlistenerlocalaccess(l_access => false);

 11. Grant connect privileges to any host for the APEX_040200 database user:
 sqlplus sys as sysdba
DECLARE ACL_PATH VARCHAR2(4000); BEGIN -- Look for the ACL currently assigned to '*' and give APEX_040200 -- the "connect" privilege if APEX_040200 -- does not have the privilege yet. SELECT ACL INTO ACL_PATH FROM DBA_NETWORK_ACLS WHERE HOST = '*' AND LOWER_PORT IS NULL AND UPPER_PORT IS NULL; IF DBMS_NETWORK_ACL_ADMIN.CHECK_PRIVILEGE(ACL_PATH, 'APEX_040200', 'connect') IS NULL THEN DBMS_NETWORK_ACL_ADMIN.ADD_PRIVILEGE(ACL_PATH, 'APEX_040200', TRUE, 'connect'); END IF; EXCEPTION -- When no ACL has been assigned to '*'. WHEN NO_DATA_FOUND THEN DBMS_NETWORK_ACL_ADMIN.CREATE_ACL('power_users.xml', 'ACL that lets power users to connect to everywhere', 'APEX_040200', TRUE, 'connect'); DBMS_NETWORK_ACL_ADMIN.ASSIGN_ACL('power_users.xml','*');
END; / COMMIT;
 run also the following command:
Alter system set shared_servers=20;
*add shared_servers=20 scope=boths;

  12. Check that Apex was installed:
SELECT comp_name, version, status FROM dba_registry WHERE comp_id='APEX';  COMP_NAME                      VERSION                        STATUS ------------------------------            ------------------------------   -----------  Oracle Application Express     4.2.2.00.11                    VALID 

13. Login first time.
 You will be asked to change ADMIN password:
 http://localhost:8080/apex/apex_admin

14. Workspace login page:  http://localhost:8080/apex 
Workspace: INTERNAL
Username: ADMIN