Usage:  kubectl exec (POD | TYPE/NAME) [-c CONTAINER] [flags] -- COMMAND [args...] [options]

[root@hdss7-21 ~]# kubectl exec nginx-web-796c86d7cd-zx2b9 -it -- /bin/bash  # 交互式
root@nginx-web-796c86d7cd-zx2b9:/# exit
exit
[root@hdss7-21 ~]# kubectl exec nginx-web-796c86d7cd-zx2b9 -- cat /etc/resolv.conf
nameserver 192.168.0.2
search default.svc.cluster.local svc.cluster.local cluster.local host.com
options ndots:5
[root@hdss7-21 ~]# kubectl exec nginx-web-796c86d7cd-zx2b9 cat /etc/resolv.conf
nameserver 192.168.0.2
search default.svc.cluster.local svc.cluster.local cluster.local host.com
options ndots:5