$ git clone https://github.com/xxx/xxx.github.io.git

$ cd xxx
$ bundle install #install required gems
$ ssh -T git@github.com # for testing connection to github
$ rake setup_github_pages # this is important for create _deploy folder in 2nd mac device
$ rake new_post["xxxx"] 
$ rake generate
$ rake deploy # it's done while no error message here.

$ git pull origin source  # git pull before push every time!
$ git add .
$ git commit -m 'Lorem ipsum dolor sit amet, consectetur adipisicing elit. Quisquam'
$ git push origin source