What happening when executing adpreclone.pl in DB and Apps Tier?

adpreclone.pl - This is the preparation phase, will collects information about the source system, creates a cloning stage area, and generates templates and drivers. All of these are to reconfigure the instance on a Target machine.
Preclone will do the following:

Convert Symbolic links
All symbolic links pointing to a static path will be converted into relative paths

Create templates
Any files under the $ORACLE_HOME that contain system specific information, will be replicated and converted into a template. These templates are placed into the $ORACLE_HOME/appsutil/template directory.

Create driver(s)
A driver file, relating to these new templates is created called instconf.drv. This contains a list of all the templates and their locations, and the destination configuration files that these templates will create.
This driver file is called instconf.drv and is placed into directory
$ORACLE_HOME/appsutil/driver

Create Stage area
A clone stage is created containing the required java code and scripts to reconfigure the instace on the Target machine

Rapid Clone stage area:
dbTier : $ORACLE_HOME/appsutil/clone
appsTier(s) - $COMMON_TOP/clone

The stage area(s) consist of the following directories:-
 jre used to run the java code on the Target machine.
 bin contains the RapidClone scripts that can be run on the Target machine:-

•    adclone.pl is the main cloning script
•    adcfgclone.pl is used to configure the Target system, this calls adclone.pl
•    adclonectx.pl is used to clone a Source XML file manually
•    adaddnode.pl is used to add a new node to the Patch History tables
•    adchkutl.sh checks for existence of require O/S utils, cc, make, ar and ld

 jlib contains all the Rapid Clone java code, jdbc libraries etc
 context contains templates used for a Target XML file
 data (Database Tier only) contains the driver file, and templates used to generate the control file SQL script
 adcrdb.zip contains the template and list of datafiles on the Source
 addbhomsrc.xml contains information on the datafile mount points of the Source
 appl (Applications Tier only) this is used when merging appltops, i.e Multi-node to Single node cloning

Executing adpreclone.pl will create a log file:-
Rapid Clone:
dbTier : $ORACLE_HOME/appsutil/log/$CONTEXT_NAME/StageDBTier_xxxxxx.log
appsTier : $APPL_TOP/admin/$CONTEXT_NAME/log/StageAppsTier_xxxxxx.log

Once this adpreclone.pl step has been completed successfully, all the java .class files under the following directories should be identical to those under $JAVA_TOP/oracle :

RDBMS $ORACLE_HOME/appsutil/java/oracle
RDBMS $ORACLE_HOME/appsutil/clone/jlib/java/oracle
$COMMON_TOP/clone/jlib/java/oracle