Git筆記

git博大精深，留一些學習上遇到的困惑，當作以後的小抄。

我覺得寫得很棒的教學: Learn git in 30 days.
學習branch、merge的線上圖形遊戲: Learn Git Branching
Commit message該怎麼寫: Commit convention

Commands

• git init Initialize a git repo at the current working directory.
• add
  • git add <file> Add new or modified file into Staged.
  • git add -A Add all changes(including new, modified, and deleted files).
  • git add --all The same as above.
  • git add . The same as above.
  • git add -u Add all modified and deleted. Use this to avoid staging ignore files.
    
• commit
  • git commit Transfer all Staged files into git repo and establish a new version.
  • git commit <file> Commit a specific <file>. It could be either Staged or Modified.
  • git commit -a This add all unstaged(Modified) files automatically. And then commit. Untracked files won't be add nor commit.
  • git commit -m "msg" msg is a note for each commit shown in git log. A commit note is reuquried. Without -m "msg", git opens an editor and ask for typing a message.
• reset
  • git reset <commit> Unstage all Staged files, which means, reseting index to <commit>. And set HEAD to <commit>. If <commit> is empty, then resets index to HEAD.
    The working tree are not affected.
  • git reset --hard <commit> Unstage files and copy files from HEAD of git repo to the disk. In other words, reset index and working tree in the same time.
    If the file in the working tree was modified, the change would be discarded.
• branch
  • git branch <branch name> Create a new branch, staying at current branch(not changing HEAD).
  • git branch -v Display all the banches, including HEAD.
• checkout
  • git checkout <branch/commit> <file> Pull specific file from <branch/commit> to working tree and index, without changing HEAD.
  • git chekcout <branch/commit> Switch HEAD to a specific <branch/commit> and pull all the files from <branch/commit> to working tree.
• merge
  1. git checkout master
  2. git merge hotfix2: Merge hotfix2 into master.
• mv
  • git mv <file name> <new file name> Rename the file/dir.
  • git mv <file name> <new path> After changing the file path without git command, git mv <the file> <path> fails to execute.
• remote
  • git remote Display names of remotes.
  • git remote -v Display names of remotes and their destinations.
  • git remote show <remote name> Display more details about a remote.
  • git remote add <remote name> <URL> Add a remote.
  • git remote remove <remote name> Remove a remote.
• .gitignore
  Change of .gitignore takes effect immediately right after it is modified without staging or commiting it. .gitignore can also be ignored.
• diff
  Show changes between commits, commit and working directory, etc.

  Instruction	Compare 1	Compare 2
  git diff	Working directory	Current version
  git diff HEAD	Working directory	Index
  git diff commit_id	Working directory	Commit version
  git diff --cached/--staged HEAD	Index	Current version
  git diff commit_1 commit_2	Commit 1	Commit 2
  git diff HEAD^ HEAD	Last version	Current version
  git diff <file>	The file in directory	Current version
  Note: Working directory = Working tree = Unstaged.

Concepts

File Status Lifecycle

• There are 4 kinds of status of a file:
  • Untracked: The file is totally new to HEAD.
  • Modified: The file is modfied after it was Committed, which means the file in the disk is different from the file in HEAD. It wont be Commited unless it is Staged.
  • Staged: The file to be committed. git commit copies/sends this kind of file into git repo/HEAD. A file in the index is called a Staged file.
  • Committed: The content of the file in the disk is the same as the one in HEAD.
  • ps: HEAD is the current working version. And it is usually the latest one in the git repo.
• Full file lifecycle:

*git rm --cached <file> where <file> is already committed and you want to remove it from the HEAD.

• Typical flow example: Step by step

Typical Flow Example: (from $1~$2)

Typical Flow Example: (from $3~$5)

1. hi
2. hihi
3. hihihi
4. matjax
   
   $hi$