title: Alpine Docker container doesn't recognize UPX as an executable
body: <p>Stackers,</p>
  
  <p>I'm using Docker to containerize my app. In the <a href="https://docs.docker.com/develop/develop-images/multistage-build/" rel="nofollow noreferrer">stage</a> below, I'm trying to pack it using <a href="https://upx.github.io/" rel="nofollow noreferrer">UPX</a>. </p>
  
  <pre><code>FROM alpine:3.8 AS compressor
  
  # Version of upx to be used(without the 'v' prefix)
  # For all releases, see https://github.com/upx/upx/releases
  ARG UPX_VERSION=3.94
  
  # Fetch upx, decompress it, make it executable.
  ADD https://github.com/upx/upx/releases/download/v${UPX_VERSION}/upx-${UPX_VERSION}-amd64_linux.tar.xz /tmp/upx.tar.xy
  RUN tar -xJOf /tmp/upx.tar.xy upx-${UPX_VERSION}-amd64_linux/upx &gt; /usr/local/bin/upx \ 
   &amp;&amp; chmod +x /usr/local/bin/upx
  
  COPY --from=builder /usr/local/bin/ace /usr/local/bin/ace
  
  RUN /usr/local/bin/upx --overlay=strip --best /usr/local/bin/ace
  </code></pre>
  
  <p>The thing is when I build the image I get the following error:</p>
  
  <blockquote>
    <p>The command '/bin/sh -c /usr/local/bin/upx --overlay=strip --best
    /usr/local/bin/ace' returned a non-zero code: 127</p>
  </blockquote>
  
  <p>For some reason, the container doesn't recognize upx as executable! Can anyone give me some pointers?</p>