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

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
 For a steady stream of TILs, [sign up for my newsletter](https://crafty-builder-6996.ck.page/e169c61186).
 
-_1210 TILs and counting..._
+_1211 TILs and counting..._
 
 ---
 
@@ -755,6 +755,7 @@ _1210 TILs and counting..._
 - [Link To The Current Page With Query Params](rails/link-to-the-current-page-with-query-params.md)
 - [List All Installable Rails Versions](rails/list-all-installable-rails-versions.md)
 - [List The Enqueued Jobs](rails/list-the-enqueued-jobs.md)
+- [Load A File When Starting Rails Console](rails/load-a-file-when-starting-rails-console.md)
 - [Load Records In Batches With find_each](rails/load-records-in-batches-with-find-each.md)
 - [Log SQL Queries Executed By ActiveRecord](rails/log-sql-queries-executed-by-activerecord.md)
 - [Mark A Migration As Irreversible](rails/mark-a-migration-as-irreversible.md)

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

@@ -0,0 +1,29 @@
+# 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.