MERCHANT_ID="12345"
SECRET_KEY="abcXYZ"

AUTH=$(echo -n "$MERCHANT_ID:$SECRET_KEY" | base64)

curl --request GET \
  --url "https://oms-external-sit.hepsiburada.com/orders/merchantid/$MERCHANT_ID" \
  --header "accept: application/json" \
  --header "authorization: Basic $AUTH" \
  --header "content-type: application/json"