How to order files by last modified time in ruby?

How about simply:

# If you want 'modified time', oldest first
files_sorted_by_time = Dir['*'].sort_by{ |f| File.mtime(f) }

# If you want 'directory change time' (creation time for Windows)
files_sorted_by_time = Dir['*'].sort_by{ |f| File.ctime(f) }