Add doctor command

lib/jekyll/commands/doctor.rb

@@ -0,0 +1,24 @@
+module Jekyll
+  module Commands
+    class Doctor < Command
+      class << self
+        def process(options)
+          site = Jekyll::Site.new(options)
+          site.read
+
+          deprecate_relative_permalinks(site)
+        end
+
+        def deprecate_relative_permalinks(site)
+          site.pages.each do |page|
+            if page.uses_relative_permalinks
+              Jekyll::Logger.warn "Deprecation:", "'#{page.path}' uses relative" +
+                                  " permalinks which will be automatically" +
+                                  " deprecated in Jekyll v1.1."
+            end
+          end
+        end
+      end
+    end
+  end
+end