[Fix #503] Prefix rails aliases with 'bundle exec'

modules/ruby/README.md

@@ -59,6 +59,7 @@ Aliases
 Functions
 ---------
 
+  - `ruby-app-root` displays the path to the Ruby application root directory.
   - `ruby-info` exposes information about the Ruby environment via the
     `$ruby_info` associative array.
 

modules/ruby/functions/ruby-app-root

@@ -0,0 +1,19 @@
+#
+# Displays the path to the Ruby application root directory.
+#
+# Authors:
+#   Sorin Ionescu <sorin.ionescu@gmail.com>
+#
+
+local root_dir="$PWD"
+
+while [[ "$root_dir" != '/' ]]; do
+  if [[ -f "$root_dir/Gemfile" ]]; then
+    print "$root_dir"
+    break
+  fi
+  root_dir="$root_dir:h"
+done
+
+return 1
+