$ brew install git-flow # Done

$ git flow init # under project folder, git-flow would ask few questions, using the default value is recommended. 
$ git flow feature start MY_FEATURE # XXX is branch name
# add some files or do something ...
$ git add .
$ git commmit -am 'do something ...'
$ git flow feature publish MY_FEATURE # push to remote repo
$ git flow feature finish MY_FEATURE

$ git flow release start RELEASE [BASE]
# e.g. git flow release start Version_1.0
$ git add .
$ git commit -am 'do something ...'
$ git flow release finish RELEASE

$ brew install git # If we want to use gitk (git GUI), this way is very convinient. (however, I think SourceTree is better.)

# rails project
$ rails new app
$ cd app
$ git init
$ git add .
$ git commit -m 'first commit'

$ git checkout -b branch_name
$ git branch # list branches in the project

# do some changes under this branch ...  

$ git add .
$ git commit -am 'some thing in this brach'

# more about `git commit` 
$ git commit -am 'xxxx' # == git add . + git commit -m 'xxxx'
$ git commit --amend # reword commit message

# go back to master and merge it

$ git checkout master
$ git merge branch_name

# push to github 

$ git remote add origin repos_git_ssh_url
$ git push --all # both master and branches
$ git push origin master # you also can push master to remote only

# reset or revert to HEAD version (HEAD refers to latest commit stage)

$ git reset HEAD --hard # --hard is dangerous (delete unstaged files)
$ git reset HEAD --soft # --soft will go back and keep files staged 
$ git reset HEAD # will go back without tracking unstaged files
$ git revert HEAD # make HEAD stage as new stage

# reset one file

$ git checkout -- <file>

# conflick of rebase (merge is the same)

$ git rebase master # under second branch
# conflick ...
# modify conflick <file>
# then 
$ git add <file>
$ git rebase --continue
# done.

# To remove untracked files / directories do:

$ git clean -fdx
# -f - force
# -d - directories too
# -x - remove ignored files too ( don't use this if you don't want to remove ignored files)

$ rails new reddit
$ cd reddit
$ git init
$ git add .
$ git commit -m "reddit init"

$ git checkout -b link_scaffold
$ rails g scaffold link title:string url:string
$ rake db:migrate
$ git add .
$ git commit -m "Generate Links Scafffold"
$ git checkout master
$ git merge link_scaffold

$ 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

$ curl http://installrails.com/update_rubygems.rb | ruby

$ gem update --system

#comment
$ \curl -sSL https://get.rvm.io | bash -s stable --ruby  
#(if error message shown -> rvm reinstall 2.1.3 --disable-binary)  
  
#modify .zshrc .bash_profile and relaunch terminal
$ echo progress-bar >> ~/.curlrc  
$ echo "source $HOME/.rvm/scripts/rvm" >> ~/.bash_profile  
$ echo "gem: --no-document" >> ~/.gemrc  
  
#test rvm ready or not  
$ type rvm | head -n 1  
$ rvm list known  
$ rvm install x.x  
$ rvm use 2.1 (rvm use 2.1 --default)

$ gem update --system #更新gem library
$ gem install bundler #安裝bundler
$ gem install rails --no-ri --no-rdoc #安裝rails

$ cd ~/.ssh
$ ssh-keygen -t rsa -C "xxx@xxx.xxx.xx"
$ pbcopy < ~/.ssh/id_rsa.pub #copy pubkey to clipboard