I am using elixir 1.3 with OTP/18. OTP/19 is out, my question how to upgrade to OTP/19 on mac?
That does strongly depend on your original way of installing OTP 18.
If you installed by any package manager, update through that one (perhaps you need to wait until the update is availablein your PM), if you installed by downloading an installer/package/whatever from erlang.org, do it again.
Unfortunately, it’s not available on homebrew yet. As soon as it’s available, I guess you may update it using
brew update && brew upgrade erlang command.
Of course, especially when using a package manager it may be, that the update takes some time until it is available, I added a NB in my original answer.