Git

• — What is git
  • — Storing snapshots(commits) of project directory with links for parent commit
  • — For version control and collaboration
• — Uses
  • — Easily to experiment knowing you can reset to working state
    • — Have multiple branches in parallel
  • — Many users work at the same time
    • — Everyone has their own separate local repository, which they sync with a remote
  • — Visual examination of the changes
  • — Maintain multiple versions of the code
  • — Allows CI/CD
• — Concepts
  • — commit
    • — a snapshot of the project directory
    • — has author, parent commit, title and description (optional)
    • — identified by a hash
    • — many things can point to a commit (hash)
      • — head
      • — a branch
      • — a tag
  • — staging area
    • — files are added to staging area before being committed
  • — branch
    • — a pointer to a commit actually
    • — you create a new branch to get a new pointer
    • — When you commit, the pointer advances to the new commit
      • — but not for the other branches
  • — remote
    • — another version of this repository over a network to which changes can be synchronized
  • — stash
  • — head
    • — reference to the current commit
    • — when you commit, the head also advance to the latest commit
  • — merging and different situations
    • — happens in different circumstances
      • — apply changes from different branch to this
      • — bring change from a remote branch (pull)
    • — When different files are changed since the last common commit
      • — newest files from both branches are used
      • — a new merge commit is created
        • — this has two parent commits
    • — When a file is changed by both branch since last commit
      • — Tries auto merging, but if the software cannot, file with both code as put in workign director
      • — You have to choose the code, add to staging area and commit
    • — Rebasing
      • — End result is same as merging but flattened to one line
      • — Changes are interleaved which might produce code that is not inconsidtent in the middle commits
• — Commands
  • — add
    • — add file or files to the staging area
  • — commit
    • — make a commit out of the staged files
  • — push
    • — push changes from a local branch to a branch in a remote
  • — pull
  • — stash
• — Internals
  • — Not storing changes but full directory
    • — Each file is stored as object identified by a cache
      • — If a file doesn't change same hash is used
  • — Identification of objects using hash
    • — A file is identified by a content hash
    • — A commit is identified by a hash
      • — Hash of multiple fields
        • — File tree
        • — Commit message
        • — Author information
• — User management