Mix.Release.make_boot_script

You're seeing just the function make_boot_script, go back to Mix.Release module for more information.

make_boot_script(release, path, modes, prepend_paths \\ [])

Specs

make_boot_script(t(), Path.t(), [{application(), mode()}], [String.t()]) ::
  :ok | {:error, String.t()}

Makes boot scripts.

It receives a path to the boot file, without extension, such as releases/0.1.0/start and this command will write start.rel, start.boot, and start.script to the given path, returning {:ok, rel_path} or {:error, message}.

The boot script uses the RELEASE_LIB environment variable, which must be accordingly set with --boot-var and point to the release lib dir.