Thanks for these excellent tutorials! They are very helpful.

I had a problem with testrpc, however; on my Ubuntu 16.04 machine I got permission errors during installation, and then errors finding scrypt when running rpc. To resolve these errors, I had to replace this command:

sudo npm install -g ethereumjs-testrpc

with these commands:

sudo npm install --unsafe-perm -g scrypt
sudo npm install --unsafe-perm -g ethereumjs-testrpc
cd /opt/node/lib/node_modules/ethereumjs-testrpc/node_modules/scrypt
sudo ln -s /opt/node/lib/node_modules/scrypt/build

Then it worked!