I changed the /etc/mongod.conf file to add relication and sharding, but it fails when I do start the MongoDB server.

Following lines were added to the config file.

_{#replication:
replSetName: "shardreplica01"
#sharding:
clusterRole: shardsvr}

Error :

mongod.service - SYSV: Mongo is a scalable, document-oriented database.
?? Loaded: loaded (/etc/rc.d/init.d/mongod; bad; vendor preset: disabled)??
?? Active: failed (Result: exit-code) since Wed 2018-09-26 09:12:52 UTC; 24min ago??
?? Docs: man:systemd-sysv-generator(8)??
?? Process: 3611 ExecStop=/etc/rc.d/init.d/mongod stop (code=exited, status=0/SUCCESS)??
?? Process: 3733 ExecStart=/etc/rc.d/init.d/mongod start (code=exited, status=1/FAILURE)??

Sep 26 09:12:51 ip-192-168-100-187.ec2.internal systemd[1]: Starting SYSV: Mongo is a scalable, document-oriented database....
Sep 26 09:12:51 ip-192-168-100-187.ec2.internal runuser[3744]: pam_unix(runuser:session): session opened for user mongod by (uid=0)
Sep 26 09:12:52 ip-192-168-100-187.ec2.internal mongod[3733]: Starting mongod: [FAILED]
Sep 26 09:12:52 ip-192-168-100-187.ec2.internal systemd[1]: mongod.service: control process exited, code=exited status=1
Sep 26 09:12:52 ip-192-168-100-187.ec2.internal systemd[1]: Failed to start SYSV: Mongo is a scalable, document-oriented database..
Sep 26 09:12:52 ip-192-168-100-187.ec2.internal systemd[1]: Unit mongod.service entered failed state.
Sep 26 09:12:52 ip-192-168-100-187.ec2.internal systemd[1]: mongod.service failed.