* openssl * base32 (from GNU coreutils)
You are recommended to use it with "pass" from https://www.passwordstore.org/
For example, to get the token for two-factor authentication:
# Usage: totp <secret> [server] totp "$(pass show otp/GitHub)" GitHub
The second parameter "GitHub" is optional and defaults to "Google", since the Google Authenticator app has become the de facto standard for such usage.