sudo apt-get install nodejs
sudo apt-get install npm

sudo npm install npm -g
npm install –g n stable

npm get registry 
npm config set registry http://registry.npm.taobao.org/
# npm config set registry https://registry.npmjs.org/

npm install gitbook-cli -g
gitbook -V

gitbook install

gitbook serve

sudo ln -s ~/Applications/calibre.app/Contents/MacOS/ebook-convert /usr/bin

vi ~/.bash_profile

export EBOOK_PATH=/Applications/calibre.app/Contents/MacOS
export PATH=$PATH:$EBOOK_PATH 

source .bash_profile

gitbook pdf

gitbook epub