[Github] 用不同RSA key pair去提交push

# 一般github建repo都會配成這樣的remote 
# git remote add origin git@github.com:<username>/<repo-name>.git

# push代碼的時侯會默認用./ssh/id_rsa和id_rsa.pub
git push origin master

# 如果你想用不同用戶和rsa key pair去提交代碼，你需要
# 1. 增加下面 ~/.ssh/config
Host github.com-user2
    HostName github.com
    User git
    IdentityFile ~/.ssh/id_rsa_user2

# 2. 修改origin url
git remote rm origin
# 注意：這裡的hostname是github.com-user2，而不是github.com
git remote add origin git@github.com-user2:<username>/<repo-name>.git

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