# File lib/mkmf.rb, line 872
def  find_executable0find_executable0(bin, path = nil)
  ext = config_string('EXEEXT')
  if File.expand_path(bin) == bin
    return bin if File.executable?(bin)
    ext and File.executable?(file = bin + ext) and return file
    return nil
  end
  if path ||= ENV['PATH']
    path = path.split(File::PATH_SEPARATOR)
  else
    path = %w[/usr/local/bin /usr/ucb /usr/bin /bin]
  end
  file = nil
  path.each do |dir|
    return file if File.executable?(file = File.join(dir, bin))
    return file if ext and File.executable?(file << ext)
  end
  nil
end