Only print colours when connected to a terminal

[gechr]

This is useful when using kubectx or kubens as part of a pipeline or when redirecting to a file and outputting colours' escape sequences is undesirable, i.e.

$ kubectx | less
$ kubens | grep "<ctx>"
$ kubectx > contexts.txt
$ kubens > namespaces.txt

[googlebot]

Thanks for your pull request. It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

📝 Please visit https://cla.developers.google.com/ to sign.

Once you've signed, please reply here (e.g. I signed it!) and we'll verify. Thanks.

---

• If you've already signed a CLA, it's possible we don't have your GitHub username or you're using a different email address on your commit. Check your existing CLA data and verify that your email is set on your git commits.
• If your company signed a CLA, they designated a Point of Contact who decides which employees are authorized to participate. You may need to contact the Point of Contact for your company and ask to be added to the group of authorized contributors. If you don't know who your Point of Contact is, direct the project maintainer to go/cla#troubleshoot. The email used to register you as an authorized contributor must be the email used for the Git commit.
• In order to pass this check, please resolve this problem and have the pull request author add another comment and the bot will run again. If the bot doesn't comment, it means it doesn't think anything has changed.

[gechr]

I signed it!

[googlebot]

CLAs look good, thanks!

[gechr]

Ergh, maybe I should search closed/rejected PRs in future... #18, #22

[ahmetb]

😃 thanks!

You can achieve these stuff with kubectl directly. Just peek at kubectx/kubens source code.

[gechr]

I very much appreciate that, and that's how I currently am doing/will continue to do in scripts regardless of whether or not kubectx outputs escape sequences when not connected to a terminal.

Relying on a shell script that's not in my control for my personal scripts is not my intention here, I'd always opt to use kubectl directly in this case. My use case is quick one-liners, as a matter of convenience (e.g. for c in $(kctx); echo $c; kubectl --context=$c get pods; fi).

[ahmetb]

This should be sufficient for your snippet

for c in $(kubectl config get-contexts -o=name);do echo $c; kubectl --context=$c get pods; done