Add Load A File When Starting Rails Console as a Rails TIL

rails/load-a-file-when-starting-rails-console.md

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+# Load A File When Starting Rails Console
+
+The `rails console` command uses `irb` under the hood. That means you can use
+any of the flags that `irb` supports when running `rails c`. One of those flags
+is `-r` which "causes `irb` to load the [specified] library using require."
+
+This `-r` flag can come in handy if we want to load a little bit of setup code
+or some utility methods for our `rails console` session.
+
+Let's say we have `vendor/show_env.rb` with this snippet of code:
+
+```ruby
+puts "#{'*' * 7}  #{Rails.env.upcase}  #{'*' * 7}
+```
+
+And we want that to display as we open the console. We can pass the path to
+that file to the `-r` flag.
+
+```bash
+$ rails console -- -r ./vendor/show_env.rb
+```
+
+[Notice the
+`--`](https://tosbourn.com/speed-up-pasting-text-into-rails-console/). That is
+to indicate that we are done with `console` specific arguments and anything
+else should be passed along to `irb`. Without the `--`, the `-r` flag won't be
+recognized.
+
+See `man irb` to see what other flags `irb` supports.