[nhumrich]

The && is just layer squashing and not really needed. You can just use run on every line. Docker even supports squashing images now, so the && doesn't matter if you squash.

[jacques_chester]

&& doesn't layer squash, it's a trick to avoid the layer commit that RUN implies.

And squashing comes with a major drawback: you lose layer caching and any hope of a vaguely-efficient rebuilding process.