title: How to list the files inside ubuntu:16.04 docker container?
body: <pre><code>I have created docker container for ubuntu:16.04 and spark.
  </code></pre>
  
  <p>my docker image name  <code>TestDocker</code></p>
  
  <p>using spark application I have copied test.txt to container /opt/ml/ location.</p>
  
  <p>when i am executing below command it is showing  like below:</p>
  
  <pre><code>docker images
  
  
      REPOSITORY                     TAG                   IMAGE ID          CREATED              SIZE
      xx.com/decision-trees-sample   latest              af30271f1528        19 minutes ago      959MB
  </code></pre>
  
  <p>then i try to execute below command</p>
  
  <pre><code>docker exec -it decision-trees-sample ls /opt/ml
  </code></pre>
  
  <p>it is showing error.</p>
  
  <p>now I want to check file is copied or not using docker command,is it  possible to check?</p>
  
  <p>how can I list(LS) files contain in /opt/ml/ ?  </p>