how to get secret data from kubectl code example

Example 1: kubectl edit secret

kubectl get secret mysecret -o json | jq '.data["foo"]="YmFy"' | kubectl apply -f -

Example 2: kubectl print secret value

kubectl get secret <my_secret_name> -o 'go-template={{index .data "<key_name>"}}' | base64 -d

ex:
kubectl get secret my-secret -o 'go-template={{index .data "username"}}' | base64 -d