install dat on a digitalocean droplet (fixing npm permissions issues)

dat.sh

# if you try to install dat on a digitalocean droplet you usually get an error like:
# sh: 1: prebuild: Permission denied
#
# this is caused by several intersecting facts:
# - digitalocean droplets, by default, only expose a root user for login
# - most node setup methods will create a node install that isn't owned by root
# - npm uses an 'undefined' user for installation
#
# and is solved in the following way:
# - taking root ownership of the node install and library install directory tree (with `chown`)
# - making npm use the calling user for installation (the `--unsafe-perm` config option)
# - remove anything installed with the wrong permissions prior to applying the previous two fixes (with `npm cache clean`)

# dependencies
sudo apt-get install build-essential libtool

# install nvm
wget -qO- https://raw.githubusercontent.com/creationix/nvm/v0.32.1/install.sh | bash

# load nvm
export NVM_DIR="$HOME/.nvm"
[ -s "$NVM_DIR/nvm.sh" ] && \. "$NVM_DIR/nvm.sh"

# install node
nvm install --lts

# fix permissions on npm dirs
sudo chown -R $(whoami) $(npm config get prefix)/{lib/node_modules,bin,share}

# make sure current user propagates to npm install
npm config set unsafe-perm true

# in case you already did the previous steps and messed up the permissions more
npm cache clean

# install dat
npm install --global dat