title: add ssh key once per login instead of once per bash
body: <p>I want to use ssh passwordless-login using authentication-key-pairs.</p>
  
  <p>I added </p>
  
  <pre><code>eval `ssh-agent -s`
  ssh-add ~/.ssh/my_p_key
  </code></pre>
  
  <p>to <code>~/.profile</code>. <strong>This doesn't work.</strong> If I use the <code>~/.bashrc</code> it works fine.</p>
  
  <p>Why do I have to set this every time I call a bash instead of every time the user logges in. I could not find any explanation.</p>
  
  <p>Is there no better way to configure this? </p>