Use below command to start the agent.
Checking the agent status:
$ /agent13c/agent_inst/bin$. /emctl status agent
Oracle Enterprise Manager Cloud Control 13c Release 4
Copyright (c) 1996, 2015 Oracle Corporation. All rights reserved.
---------------------------------------------------------------
Agent is Not RunningStarting the Agent
$ /agent12c/agent_inst/bin$ ./emctl start agent
Oracle Enterprise Manager Cloud Control 13c Release 4
Copyright (c) 1996, 2015 Oracle Corporation. All rights reserved.
Starting agent .............................. started.
or
Restarting the Agent
$ /agent12c/agent_inst/bin$ ./emctl restart agent
Oracle Enterprise Manager Cloud Control 13c Release 4
Copyright (c) 1996, 2015 Oracle Corporation. All rights reserved.
Starting agent .............................. started.
Check the status:
$ /agent12c/agent_inst/bin$ ./emctl status agent
Oracle Enterprise Manager Cloud Control 13c Release 4
Copyright (c) 1996, 2015 Oracle Corporation. All rights reserved.
---------------------------------------------------------------
Agent Version : 13.4.0.0
OMS Version : 13.4.0.0
Protocol Version : 12.1.0.1.0
Agent Home : /agent13c/agent_inst
Agent Log Directory : /agent13c/agent_inst/sysman/log
Agent Binaries : /agent13c/agent_13.4.0.0
Agent Process ID : 79845
Parent Process ID : 79786
Agent URL : https://192.168.100.20:34440/emd/main/
Local Agent URL in NAT : https://192.168.100.20:34440/emd/main/
Repository URL : https://em13c.abuzer.local:1159/empbs/upload
Started at : 2020-03-19 09:46:09
Started by user : oracle
Operating System : Linux Version 4.1.12-124.31.1.1
Last Reload : (none)
Last successful upload : 2020-03-19 09:46:09
Last attempted upload : 2020-03-19 09:46:09
Total Megabytes of XML files uploaded so far : 0.02
Number of XML files pending upload : 12
Size of XML files pending upload(MB) : 700
Available disk space on upload filesystem : 33.92%
Collection Status : Collections enabled
Heartbeat Status : Ok
Last attempted heartbeat to OMS : 2020-03-19 09:46:09
Last successful heartbeat to OMS : 2020-03-19 09:46:09
Next scheduled heartbeat to OMS : 2020-03-19 09:46:09
---------------------------------------------------------------
Agent is Running and Ready