eachdir - Run a command in each child directory.

eachdir.rb

#!/usr/bin/env ruby -w

# eachdir - Run a command in each child directory.

abort "need command" unless ARGV[0]
abort "quote the command" unless ARGV.size == 1

def banner(path)
  dirname, basename = File.split path
  puts
  puts "== #{basename} in #{dirname} ".ljust 80, "="
  puts
end

root = Dir.pwd

dirs = Dir.entries(root).
         select { |ref| File.directory? ref  }.
         select { |dir| dir =~ /^[a-z]/i     }.
         map    { |dir| File.join(root, dir) }

dirs.each do |dir|
  Dir.chdir dir
  banner dir
  system ARGV[0]
end

Dir.chdir root