title: Docker starting container process caused "exec: \"arg\": executable file not found in $PATH": unknown.
body: <p>My task is to create <code>Dockerfile</code> such that it works the following way:</p>
  
  <p><code>docker build -t test .</code><br>
  Returns <code>Image named test successfully created</code></p>
  
  <p><code>docker run --rm test</code><br>
  Returns <code>Hello world!</code></p>
  
  <p><code>docker run --rm test Universe</code><br>
  Returns <code>Hello Universe!</code></p>
  
  <p>What I have so far:<br>
  <strong>Dockerfile</strong></p>
  
  <pre><code>FROM ubuntu:14.04
  
  LABEL maintainer="trthhrtz"
  
  CMD if [ $# -eq 0 ]; then echo "Hello world!"; else echo "Hello " + $@ + "!"; fi
  </code></pre>
  
  <p>It does not work in case of input arguments, the error is:<br>
  <code>docker: Error response from daemon: OCI runtime create failed: container_linux.go:348: starting container process caused "exec: \"Universe\": executable file not found in $PATH": unknown.<br>
  ERRO[0000] error waiting for container: context canceled</code></p>