--show-labels  显示所有标签
-l app         仅显示标签为app的资源
-l app=nginx   仅显示包含app标签，且值为nginx的资源

[root@hdss7-21 ~]# kubectl get pod -n app --show-labels 
NAME       READY   STATUS    RESTARTS   AGE   LABELS
pod-02     1/1     Running   0          9h    app=nginx,release=stable,version=v1.12
pod-demo   1/1     Running   9          9h    app=centos7,environment=dev,release=stable
[root@hdss7-21 ~]# kubectl get pod -n app --show-labels -l app
NAME       READY   STATUS    RESTARTS   AGE   LABELS
pod-02     1/1     Running   0          9h    app=nginx,release=stable,version=v1.12
pod-demo   1/1     Running   9          9h    app=centos7,environment=dev,release=stable
[root@hdss7-21 ~]# kubectl get pod -n app --show-labels -l app=nginx
NAME     READY   STATUS    RESTARTS   AGE   LABELS
pod-02   1/1     Running   0          9h    app=nginx,release=stable,version=v1.12