title: Where are the directory created from dockerfile and how do I access it?
body: <p>I am new to Docker and have a simple question. Let say I created an image to <code>mkdir</code> a folder using dockerfile below:</p>
  
  <pre><code>FROM biocontainers/biocontainers:latest
  
  USER root
  
  RUN mkdir -p /bin/testFolder
  </code></pre>
  
  <p>I built the image as below:</p>
  
  <pre><code>docker image build -f dockerfile -t tmp:test .
  </code></pre>
  
  <p>The message output is as below:</p>
  
  <pre><code>Sending build context to Docker daemon  12.77GB
  Step 1/3 : FROM biocontainers/biocontainers:latest
  latest: Pulling from biocontainers/biocontainers
  22dc81ace0ea: Pull complete
  1a8b3c87dba3: Pull complete
  91390a1c435a: Pull complete
  07844b14977e: Pull complete
  b78396653dae: Pull complete
  37acb86aada8: Pull complete
  dea6dd7e30dd: Pull complete
  5f8154b871f1: Pull complete
  06b022b2c83f: Pull complete
  9b2c8a4ecb8d: Pull complete
  7b30ef549338: Pull complete
  9b34fc643fc1: Pull complete
  52c0fab077ab: Pull complete
  db8c4567241d: Pull complete
  db7cd43b1320: Pull complete
  c0db2ee4b7f4: Pull complete
  Digest: sha256:c6f082f5658c6d31a5ccb537289d1ce777f51b7285c465fe0efa219058471c81
  Status: Downloaded newer image for biocontainers/biocontainers:latest
   ---&gt; 932119eee190
  Step 2/3 : USER root
   ---&gt; Running in a707d5e1b39d
  Removing intermediate container a707d5e1b39d
   ---&gt; a1c02b8e9ed3
  Step 3/3 : RUN mkdir -p /bin/testFolder
   ---&gt; Running in 88f453470cc6
  Removing intermediate container 88f453470cc6
   ---&gt; 12d57c57c415
  Successfully built 12d57c57c415
  Successfully tagged tmp:test
  </code></pre>
  
  <p>How do I know where <code>/bin/testFolder</code> is located and how do I access it? Thanks. </p>