Nerves.Runtime

Nerves.Runtime is an optional component of Nerves but it's really handy and has a small footprint. Here are some of its features:

• A custom shell for debugging and running commands in a bash shell like environment
• A small Linux kernel uevent application for capturing hardware change events and more
• More to come...

The Nerves Runtime Shell

Nerves devices typically only expose an Elixir or Erlang shell prompt. While this is handy, so tasks are quicker to run in a more bash shell-like environment. The Nerves runtime shell provides a limited approximation to this that can be run without leaving the Erlang runtime. Here's an example run:

iex(1)> [Ctrl+G]
User switch command
 --> s sh
 --> j
   1  {erlang,apply,[#Fun<Elixir.IEx.CLI.1.112225073>,[]]}
   2* {sh,start,[]}
 --> c
Nerves Interactive Command Shell

Type Ctrl+G to exit the shell and return to Erlang job control.
This is not a normal shell, so try not to type Ctrl+C.

/srv/erlang[1]>

There are a few caveats to using this shell right now, so you'll have to be careful when you use it:

1. Ctrl+C Ctrl+C exits the Erlang VM and will reboot or hang your system depending on how erlinit is configured.
2. Because of the Ctrl+C caveat, you can't easily break out of long running programs. As a workaround, start another shell using Ctrl+G and kill the offending program.
3. Commands are run asynchronously. This is unexpected if you're used to a regular shell. For most commands, it's harmless. One side effect is that if a command changes the current directory, it could be that the prompt shows the wrong path.

Installation

The package can be installed by adding nerves_runtime to your list of dependencies in mix.exs:

def deps do
  [{:nerves_runtime, "~> 0.2.0"}]
end

Docs can be found at https://hexdocs.pm/nerves_runtime.