I typed this:
>rails console
and got this:
Usage:
rails new APP_PATH [options]
Options:
[--skip-gemfile]
In case anyone else hits this, my symptoms were:
I'd deployed my application with Capistrano 3
I cd'd into my application directory, and rails console didn't work
Turned out I'd included the bin folder as a symlinked directory in my cap deploy, as follows:
set :linked_dirs, %w{log tmp/pids tmp/cache tmp/sockets vendor/bundle public/system}
... and my bin directory in 'shared' was empty.
Two fixes:
I then re-deployed and it works.