Checkout

換branch、換到某commit的狀態

$ git checkout branch-name
$ git checkout xxxxx  # <- commit hash

換到remote的branch

$ git checkout --track origin/daves_branch
# Same as "git checkout -b [branch] [remotename]/[branch]"

Reference

開新branch

$ git checkout -b some-branch
$ git push --set-upstream origin some-branch

gitignore

加入.gitignore

vim .gitignore
git add .gitignore
git commit -m "Add .gitignore"

更新tracking files

# Remove tracking in git
$ git rm -r --cached .
$ git status
# 應該一堆綠色(deleted)和一堆紅色(untracked)...
$ git add .
$ git status
# 需要從git ignore走的檔案會顯示為"deleted"
$ git commit -m "Remove tracking some files"

Log: 查看git history

$ git log

Reset: 取消local commit

$ git reset HEAD~1  # 取消一個local commit
$ git reset HEAD~2  # 兩個

Revert: 回復到幾個commit前的狀態

重要概念1：不要想著能回到以前，git是version control工具，任何動作和history都需要被紀錄，包括「回復舊version」這動作。
重要概念2：每revert一個commit都是一次改動，代表需要一次commit，但可以找方法squash做同一次commit。

$ git revert HEAD~1  # revert最後一個commit
$ git revert HEAD~2  # 兩個
# ...
$ git revert master~3..master  # A <- B <- C <- D <- BCD'   <- HEAD

# 途中不用自動commit，只留下最後一個change自己commit
# 不建議使用
$ git revert --no-commit master~3..master  # A <- B <- C <- D <- BCD'   <- HEAD

Reference

Rebase:

Combine previous commits

可以和上面的revert組合使用，例如revert master~4..master後，出現四個用來revert的commits，然後用rebase來變做同一個commit。

$ git rebase -i HEAD~4
# rebase HEAD~4: rebase至第四新的commit
# -i: 用interactive的方式決定如何處理之前的commits

  1 pick af9ccec Upgrade to expo v25.0.0 dependencies  # 第一個不能是squash
  2 squash c6f387a Update version  # squash到上一個commit當中
  3 squash e9564d4 Update ios android version
  4 squash c588e11 Update yarn.lock to expo v25.0.0
  5 
  6 # Rebase 32f1edc..c588e11 onto 32f1edc (4 commands)
  7 #
  8 # Commands:
  9 # p, pick = use commit
 10 # r, reword = use commit, but edit the commit message
 11 # e, edit = use commit, but stop for amending
 12 # s, squash = use commit, but meld into previous commit
 13 # f, fixup = like "squash", but discard this commit's log message
 14 # x, exec = run command (the rest of the line) using shell
 15 # d, drop = remove commit
 16 #
 17 # These lines can be re-ordered; they are executed from top to bottom.
 18 #
 19 # If you remove a line here THAT COMMIT WILL BE LOST.
 20 #
 21 # However, if you remove everything, the rebase will be aborted.
 22 #
 23 # Note that empty commits are commented out

Reference

Amend: 修改commit

修改上一條local commit的message，並加入現在的staged changes

$ git commit --amend
# 或直接
$ git commit --amend -m "xxxx"