title: How to just temporarily disable apt proxy setting for installing packages
body: <p>Apt is able to use proxy to install additional packages along with dependencies.
  I'm working on a Python project and I needed some extra package that provides a library.</p>
  
  <pre><code>---&gt; sudo apt-get update
  Err:1 http://security.ubuntu.com/ubuntu bionic-security InRelease
    Could not resolve 'proxy.internal'
  Err:2 http://archive.ubuntu.com/ubuntu bionic InRelease
    Could not resolve 'proxy.internal'
  Err:3 http://archive.ubuntu.com/ubuntu bionic-updates InRelease
    Could not resolve 'proxy.internal'
  Err:4 http://archive.ubuntu.com/ubuntu bionic-backports InRelease
    Could not resolve 'proxy.internal'
  Reading package lists... Done
  W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/bionic/InRelease  Could not resolve 'proxy.internal'
  W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/bionic-updates/InRelease  Could not resolve 'proxy.internal'
  W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/bionic-backports/InRelease  Could not resolve 'proxy.internal'
  W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/bionic-security/InRelease  Could not resolve 'proxy.internal'
  W: Some index files failed to download. They have been ignored, or old ones used instead.
  </code></pre>
  
  <p>How to temporarily disable proxy (without altering the permanent options/settings)? Preferably, from the command line.</p>