What is age? It means Actually Good Encryption. It's a tool that makes encryption easy, by not having many options.
Use your package manager to install
To encrypt to someone's public key:
age --encrypt --recipient publicKeyHere --output encryptedFile.txt.age inputFile.txt
You can provide many recipients by repeating
--recipient publicKey for each one.
If you want to make your own key, so that you can be a recipient, then you use
age-keygen --output key.txt
Now your private key is in
key.txt (never share it), and the public key (share that one) is printed to the screen, and is also in
To decrypt a message sent to you:
age --decrypt --identity path/to/your/key.txt encryptedFile.txt.age