title: Linux commands in Alpine docker image +755 invalid mode
body: <p>I am building a Docker image using the Node:12 base image. I am trying to switch it to use Node:12-alpine instead due to the smaller image size. I have installed bash and shadow in Alpine to be able to run <code>chmod</code> commands.</p>
  
  <p>I am running into an error with one of the RUN commands <code>RUN chmod +755</code>. The error message: <code>chmod: invalid mode '+755'</code></p>
  
  <p>Note that this works using the Node:12 base image, so I think I just need to install another package in Alpine linux? Thanks!</p>
  
  <pre><code>FROM node:12.8-alpine
  
  # Create working directory
  RUN mkdir -p /home/node/app
  
  # Set working directory
  WORKDIR /home/node/app
  
  # Install bash and shadow for permissions chmod commands
  RUN apk add --no-cache bash &amp;&amp; apk add shadow
  
  # Add `/home/node/app/node_modules/.bin` to $PATH
  ENV PATH /home/node/app/node_modules/.bin:$PATH
  
  # Copy code
  COPY --chown=node . /home/node/app
  
  # Update umask
  RUN chmod +755 /home/node/app/entrypoint.sh &amp;&amp; \
      echo 'umask 002' &gt;&gt; /home/node/.profile &amp;&amp; \
      echo 'umask 002' &gt;&gt; /home/node/.bashrc &amp;&amp; \
      npm install
  
  ENTRYPOINT ["./entrypoint.sh"]
  
  CMD [ "npm", "start" ]
  </code></pre>