title: how to make `cd` call in Rust?
body: <p>I'm writing a command-line tool using Rust. I want to <code>cd</code> to the wanted dictionary when I execute my Rust command-line tool.</p>
  <p>I use <code>env::set_current_dir(path)</code>, but it does not work. After that, I use <code>nix</code>, call <code>nix::unistd::chdir(path)</code>, but it does not work either.</p>
  <p>So how can I archieve the goal of chaging command dictionary? How to make <code>cd</code> call in Rust.</p>