How can I add a secret in GitHub Actions using my terminal?

I've created a simple CLI that can help you achieve that - https://github.com/unfor19/githubsecrets

This CLI is based on the official GitHub Actions Secrets API

Install with pip

$ pip install githubsecrets
...
$ ghs --help
...

Or use with Docker; you must supply all arguments, prompts are not available in Docker mode

macOS and Linux

$ docker run -v $HOME:/root unfor19/githubsecrets --help
Usage: ghs [OPTIONS] COMMAND [ARGS]...

Windows

$ docker run --rm -v c:/Temp:/root unfor19/githubsecrets --help
Usage: ghs [OPTIONS] COMMAND [ARGS]...