By default, when you run
az login, it will output the subscriptions associated with your account.
There’s no way to tell the Azure CLI to suppress output.
If you don’t want it to print subscriptions, then use this hack:
az login --query "[?n]|"
I’ve asked the CLI team to provide a “-o none” option and that request is being tracked here: https://github.com/Azure/azure-cli/issues/5667