把目前使用中，而且沒有git的資料夾track remote branch

1. 連線的PC or server要有SSH Key, 並且把Public key的內容貼到Bitbucket的Repo設定裡 Step by step tutorial: https://confluence.atlassian.com/bitbucket/set-up-an-ssh-key-728138079.html
   1. ssh-keygen
   2. Press the Enter or Return key to accept the default location. (Or leave it empty)
   3. Enter and re-enter a passphrase when prompted.
   4. ls ~/.ssh id_rsa id_rsa.pub
   5. eval ssh-agent
      eval `ssh-agent`

      1	eval `ssh-agent`

   6. ssh-add ~/.ssh/<private_key_file>
   7. cat ~/.ssh/id_rsa.pub
   8. Paste public key to bitbucket
2. Git commands to track remote branch
   1. git init
   2. git add .
   3. git commit -m ‘Init git’ (Current branch is master)
   4. git remote add origin git@gitserver:/opt/git/project.gitReference or
      git branch --set-upstream-to=origin/master master

      1	git branch --set-upstream-to=origin/master master

   5. git fetch
   6. git branch -u origin/master

Fix “detached HEAD” error

https://gitbook.tw/chapters/faq/detached-head.html

Fix “refusing to merge unrelated histories” error:

1. Force pull
   git pull origin master --allow-unrelated-histories

   1	git pull origin master --allow-unrelated-histories

2. Fix conflicts maybe. Uploading files with conflicts by FTP could be the fastest solution.
3. git add .
4. commit
5. Done

Note: 執行完上方command後，兩方client有不同步或是持續出現conflict的問題，重覆修正幾次之後就好了。原因不明。 Reference:

1. https://stackoverflow.com/questions/24916708/track-existing-folder-from-remote-git-repo
2. Track Remote Branch https://stackoverflow.com/questions/520650/make-an-existing-git-branch-track-a-remote-branch
3. Common commands related to remote https://backlog.com/git-tutorial/tw/reference/remote.html