[root@master1 ~]# kubectl get nodes
NAME      STATUS   ROLES    AGE    VERSION
master1   Ready    master   133m   v1.19.0
worker1   Ready    <none>   81m    v1.19.0
worker2   Ready    <none>   79m    v1.19.0
[root@master1 ~]# kubectl get namespace
NAME              STATUS   AGE
default           Active   4h9m
kube-node-lease   Active   4h9m
kube-public       Active   4h9m
kube-system       Active   4h9m
You have new mail in /var/spool/mail/root
[root@master1 ~]# kubectl create namespace test1
namespace/test1 created
[root@master1 ~]# kubectl get namespace
NAME              STATUS   AGE
default           Active   4h13m
kube-node-lease   Active   4h13m
kube-public       Active   4h13m
kube-system       Active   4h13m
test1             Active   22s
[root@master1 ~]# kubectl get ns
NAME              STATUS   AGE
default           Active   4h13m
kube-node-lease   Active   4h13m
kube-public       Active   4h13m
kube-system       Active   4h13m
test1             Active   46s
[root@master1 ~]# mkdir yamldir
[root@master1 ~]# cd yamldir/
[root@master1 yamldir]# vim 01_create_ns.yaml
[root@master1 yamldir]# cat 01_create_ns.yaml
apiVersion: v1
kind: Namespace
metadata:
  name: test2
[root@master1 yamldir]# kubectl apply -f 01_create_ns.yaml 
namespace/test2 created
[root@master1 yamldir]# kubectl get ns
NAME              STATUS   AGE
default           Active   4h24m
kube-node-lease   Active   4h24m
kube-public       Active   4h24m
kube-system       Active   4h24m
test1             Active   11m
test2             Active   29s
[root@master1 yamldir]# kubectl get ns
NAME              STATUS   AGE
default           Active   4h27m
kube-node-lease   Active   4h27m
kube-public       Active   4h27m
kube-system       Active   4h27m
test1             Active   14m
test2             Active   3m
[root@master1 yamldir]# kubectl delete namespace test1
namespace "test1" deleted
[root@master1 yamldir]# kubectl get ns
NAME              STATUS   AGE
default           Active   4h28m
kube-node-lease   Active   4h28m
kube-public       Active   4h28m
kube-system       Active   4h28m
test2             Active   3m56s
[root@master1 yamldir]# kubectl get ns
NAME              STATUS   AGE
default           Active   4h28m
kube-node-lease   Active   4h28m
kube-public       Active   4h28m
kube-system       Active   4h28m
test2             Active   4m17s
[root@master1 yamldir]# kubectl delete -f 01_create_ns.yaml 
namespace "test2" deleted
[root@master1 yamldir]#