1) Create a rpm package on Enterprise Manager 12c

a) as Root :

# yum install rpmbuild
# mkdir /usr/lib/oracle

b) as oracle user

# cd $<OMS_HOME>/bin/
# emcli get_supported_platforms
-----------------------------------------------

Version = 12.1.0.3.0
 Platform = Linux x86-64
-----------------------------------------------
Platforms list displayed successfully.

#  emcli get_agentimage_rpm -destination=/tmp/agentRPM -platform="Linux x86-64" \
	-version=12.1.0.3.0

Platform:Linux x86-64
Destination:/tmp/agentRPM
Exalogic:false
 Checking for disk space requirements...
 === Partition Detail ===
Space free : 6 GB
Space required : 1 GB
RPM creation in progress ...
Check the logs at
/Oracle/gc_inst/em/EMGC_OMS1/sysman/emcli/setup/.emcli/get_agentimage_rpm_date-PM.log
Copying agent image from software library
to /tmp/agentRPM
Setting property ORACLE_HOME to:/Oracle/middleware/oms
calling pulloneoffs with arguments:/Oracle/middleware/oms/Oracle/middleware/oms/sysman/agent/ \
	12.1.0.3.0_AgentCore_226.zip12.1.0.3.0Linux
x86-64/tmp/agentRPMtrue
Agent Image copied successfully...
Creation of RPM started...
RPM creation successful.
Agent image to rpm conversion completed successfully

2) Copy it on all new hosts and install it. 

As Root user :

c) check and install rpm file

# rpm -ivh --test oracle-agt-12.1.0.3.0-1.0.x86_64.rpm 
Preparing...          
     ########################################### [100%]
# rpm -ivh oracle-agt-12.1.0.3.0-1.0.x86_64.rpm 
Preparing...          
     ########################################### [100%]
Running the prereq
   1:oracle-agt      
      ########################################### [100%]

Agent RPM installation is completed successfully. Now to configure the agent follow the below steps:

1. Edit the properties file: /usr/lib/oracle/agent/agent.properties with the correct values

2. Execute the script /etc/init.d/oracle-agt RESPONSE_FILE=/usr/lib/oracle/agent/agent.properties

d) create a user for the agent:

# useradd -m -d /home/em12adm -s /bin/bash -g dba -G oinstall em12adm
# passwd em12adm

e) Edit file /usr/lib/oracle/agent/agent.properties

# vi /usr/lib/oracle/agent/agent.properties 
OMS_HOST=<host_Enterprise_Manager>
OMS_PORT=<HTTPS
Upload Port >
AGENT_REGISTRATION_PASSWORD=oracle
AGENT_USERNAME=em12adm
AGENT_GROUP=dba
ORACLE_HOSTNAME=oraclevm-mgmt

# chown -R em12adm:dba /usr/lib/oracle/agent/

Start agent and register the new host server on EM12c

  #  /etc/init.d/oracle-agt RESPONSE_FILE=/usr/lib/oracle/agent/agent.properties

Now you have registered on EM12C your new target host.