Elixir's Logger to stderr

gistfile1.txt

$ mix new foo
* creating README.md
* creating .gitignore
* creating mix.exs
* creating config
* creating config/config.exs
* creating lib
* creating lib/foo.ex
* creating test
* creating test/test_helper.exs
* creating test/foo_test.exs

Your mix project was created successfully.
You can use mix to compile it, test it, and more:

    cd foo
    mix test

Run `mix help` for more commands.


$ cd foo

$ mix test
Compiled lib/foo.ex
Generated foo app
.

Finished in 0.07 seconds (0.07s on load, 0.00s on tests)
1 test, 0 failures

Randomized with seed 470405

$ mix run -e 'require Logger; Logger.info "hello"'
15:39:45.130 [info]  hello

$ mix run -e 'require Logger; GenEvent.add_handler(Logger, {Logger.Backends.Console, :stderr}, {:stderr, []}); Logger.info "hello"'

15:39:49.954 [info]  hello

15:39:49.954 [info]  hello

$ mix run -e 'require Logger; GenEvent.add_handler(Logger, {Logger.Backends.Console, :stderr}, {:stderr, []}); Logger.info "hello"' 2>/dev/null

15:39:53.835 [info]  hello

15:39:53.835 [info]  hello