Building Caffe2 and Pytorch for Ubuntu 18.04 LTS

I am trying to export my pytorch model to Android devices. It seems that using onnx and caffe2 is the easiest way to do so. Here, I will describe the steps to build and install pytorch & caffe2 for Ubuntu 18.04 LTS.

Basically, one has to follow the instructions here, but I had some problems building. The easiest way to build is to disable all unnecessary features. For example, since I am only going to port it to caffe2 and do not intend to use GPU for running pytorch model (at least for this python environment), I can set some flags:
$ export NO_CUDA=1
$ export NO_DISTRIBUTED=1

Also, I will build pytorch and caffe2 together. Hence, I set the flag
$ export FULL_CAFFE2=1

With these environment variables set, I successfully built and installed caffe2 and pytorch from the source, following the official instruction.

Happy hacking!