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#Add nginx keys
wget -O - http://nginx.org/keys/nginx_signing.key | sudo apt-key add -
#Backup current sources
sudo cp /etc/apt/sources.list /etc/apt/sources.list.bak
#Add following repositories to `/etc/apt/sources.list`
echo "deb http://nginx.org/packages/mainline/ubuntu/ trusty nginx" | sudo tee -a /etc/apt/sources.list
echo "deb-src http://nginx.org/packages/mainline/ubuntu/ trusty nginx" | sudo tee -a /etc/apt/sources.list
#Update repositories and install nginx
sudo apt-get update
sudo apt-get install nginx