Q. systemctl: command not found
[firstname.lastname@example.org ~]# sudo systemctl daemon-reload
sudo: systemctl: command not found
Ans. CentOS 6 does not use systemd.
On CentOS 6 we use chkconfig command to start/active the service automatically at boot.
If you want to stop/start the services then use the service command.
service <service-name> status/start/stop