Here is the typo:
[user@host ~]$ oc cp /tmp/index.html apache-app-kc82c:/var/www/htnl/
[user@host ~]$ oc exec -it apache-app-kc82c -- ls /var/www/html index.bak
Ir seems that if you copy /tmp/index.html to the container, the out of the ls command on the container should be index.html.
