The Find module supports the top-down traversal of a set of file paths.

For example, to total the size of all files under your home directory, ignoring anything in a “dot” directory (e.g. $HOME/.ssh):

require 'find'

total_size = 0

Find.find(ENV["HOME"]) do |path|
  if FileTest.directory?(path)
    if File.basename(path)[0] == ?.
      Find.prune       # Don't look any further into this directory.
    else
      next
    end
  else
    total_size += FileTest.size(path)
  end
end
Methods
F
P
Class Public methods
find(*paths)

Calls the associated block with the name of every file and directory listed as arguments, then recursively on their subdirectories, and so on.

Returns an enumerator if no block is given.

See the Find module documentation for an example.

Source: show | on GitHub 

# File lib/find.rb, line 37
def find(*paths) # :yield: path
  block_given? or return enum_for(__method__, *paths)

  paths.collect!{|d| raise Errno::ENOENT unless File.exist?(d); d.dup}
  while file = paths.shift
    catch(:prune) do
      yield file.dup.taint
      begin
        s = File.lstat(file)
      rescue Errno::ENOENT, Errno::EACCES, Errno::ENOTDIR, Errno::ELOOP, Errno::ENAMETOOLONG
        next
      end
      if s.directory? then
        begin
          fs = Dir.entries(file)
        rescue Errno::ENOENT, Errno::EACCES, Errno::ENOTDIR, Errno::ELOOP, Errno::ENAMETOOLONG
          next
        end
        fs.sort!
        fs.reverse_each {|f|
          next if f == "." or f == ".."
          f = File.join(file, f)
          paths.unshift f.untaint
        }
      end
    end
  end
end
prune()

Skips the current file or directory, restarting the loop with the next entry. If the current file is a directory, that directory will not be recursively entered. Meaningful only within the block associated with ::find.

See the Find module documentation for an example.

Source: show | on GitHub 

# File lib/find.rb, line 74
def prune
  throw :prune
end