gsutil was working as a stand-alone on my system. Then I installed SDK, including some authentication stuff. Now gsutil says my credentials are invalid.
$ gcloud auth login wolfvolpi@gmail.com
WARNING: `gcloud auth login` no longer writes application default credentials.
If you need to use ADC, see:
gcloud auth application-default --help
You are now logged in as [redacted].
Your current project is [redacted]. You can change this setting by running:
$ gcloud config set project PROJECT_ID
$ gsutil ls
Your credentials are invalid. Please run
$ gcloud auth login
How to set my credentials so that gsutil runs again?
$ gcloud version
Google Cloud SDK 146.0.0
core 2017.02.28
core-nix 2017.02.28
gcloud
gcloud-deps 2017.02.28
gcloud-deps-linux-x86_64 2017.02.28
gsutil 4.22
gsutil-nix 4.22