def chdir(dir)
      run_silently :pushd, dir.to_s
      result = Dir.chdir(dir) { yield }
      run_silently :popd
      result
    end
def chdir(dir)
      run_silently :pushd, dir.to_s
      result = Dir.chdir(dir) { yield }
      run_silently :popd
      result
    end
Run commands inside the given directory.