Only if they’re not already present on your system. If the elixir command succeeds, that part of the script is skipped!

We based it off of what the new phoenix installer does, and we want to try to be unified. We are going to be adding an option for if you are using the fish shell, we could potentially add a flag or explanation that it will happen? Ultimately there are a lot of audiences for this and it can be difficult to make it exactly what everyone needs. Perhaps for those with more discerning sensibilities there could be a “show script” button that will link to the underyling script?

No - you can check out the shell script from the first part of the generated command to see what it does, eg.

https://ash-hq.org/new/test?install=phoenix

When you run the script on your machine, it installs the phx_new and igniter_new Hex archives, and uses igniter.new to generate a new Mix project using phx.new