Adding & locking new user account

sudo su
adduser ${Var_user}
usermod -L ${Var_user}

Append groups tty & dialout to the new user account

usermod -a -G tty ${Var_user}
usermod -a -G dialout ${Var_user}

Install dependencies via apt-get

apt-get update
apt-get install python-pip python-dev python-setuptools python-virtualenv git libyaml-dev build-essential

Login to locked user account for source install operations

su - ${Var_user}
git clone
cd OctoPrint
virtualenv venv
./venv/bin/pip install pip --upgrade
./venv/bin/python install
mkdir ${HOME}/.octoprint

Start the server from within locked user account with the following line

${HOME}/OctoPrint/venv/bin/octoprint serve

Or from root via

su - ${Var_user} '${HOME}/OctoPrint/venv/bin/octoprint serve'

Updating & re-installing

su - ${Var_user}
cd ${HOME}/OctoPrint
git pull
./venv/bin/python clean
./venv/bin/python install