Ubuntu CA Cerificate

cd /usr/local/share/ca-certificates
mkdir folder
chmod 744 folder
cd folder
wget <cert in ascii format>
chmod 644 file
sudo update-ca-certificates --verbose

Check that your cert is getting added.

All certs are then added to /etc/ssl/certs/ca-certificates.crt

Can then use for example:
export NODE_EXTRA_CA_CERTS='/etc/ssl/certs/ca-certificates.crt