Merge pull request #8964 from mattdbridges/specify-log-to-clear

Clear specific logs when using `rake log:clear`

guides/source/command_line.md

@@ -355,7 +355,7 @@ rake assets:clean       # Remove compiled assets
 rake assets:precompile  # Compile all the assets named in config.assets.precompile
 rake db:create          # Create the database from config/database.yml for the current Rails.env
 ...
-rake log:clear          # Truncates all *.log files in log/ to zero bytes
+rake log:clear          # Truncates all *.log files in log/ to zero bytes (specify which logs with LOGS=test,development)
 rake middleware         # Prints out your Rack middleware stack
 ...
 rake tmp:clear          # Clear session, cache, and socket files from tmp/ (narrow w/ tmp:sessions:clear, tmp:cache:clear, tmp:sockets:clear)

railties/CHANGELOG.md

 ## Rails 4.0.0 (unreleased) ##
 
+*   Specify which logs to clear when using the `rake log:clear` task.
+    (e.g. rake log:clear LOGS=test,staging)
+
+    *Matt Bridges*
+
 *   Allow a `:dirs` key in the `SourceAnnotationExtractor.enumerate` options
     to explicitly set the directories to be traversed so it's easier to define
     custom rake tasks.

railties/lib/rails/tasks/log.rake

 namespace :log do
-  desc "Truncates all *.log files in log/ to zero bytes"
+  desc "Truncates all *.log files in log/ to zero bytes (specify which logs with LOGS=test,development)"
   task :clear do
-    FileList["log/*.log"].each do |log_file|
-      f = File.open(log_file, "w")
-      f.close
+    log_files.each do |file|
+      clear_log_file(file)
     end
   end
+
+  def log_files
+    if ENV['LOGS']
+      ENV['LOGS'].split(',')
+                  .map    { |file| "log/#{file.strip}.log" }
+                  .select { |file| File.exists?(file) }
+    else
+      FileList["log/*.log"]
+    end
+  end
+
+  def clear_log_file(file)
+    f = File.open(file, "w")
+    f.close
+  end
 end