Git lightning talk

gistfile1.txt

Understanding the concepts

  - The Git Parable, but Tom Preston-Werner
    http://tom.preston-werner.com/2009/05/19/the-git-parable.html
  - git is a bucket of commits
    - most commits have one parent, and a blob
    - some commits have 2 parents (merges)
    - some commits have 1 parents (first commit!)
  - refs
    - branches: pointers to a commit - moves over time
    - tags: pointers to a commit - does not move

finding unmerged commits
  git branch -a --no-merged
  git branch -a --merged

finding lost commits
  1) don't get lost
    a) where are you?
      zshrc with oh-my-zsh
        plugins=(git ...)
      bash_profile:
        source /usr/local/etc/bash_completion.d/git-prompt.sh
        source /usr/local/etc/bash_completion.d/git-completion.bash
        PS1='\n\A \u@\h \W$(__git_ps1 " (%s)")\$ '
    b) visualize it
      GitX (forked): http://rowanj.github.io/gitx/
      GitHub's client, gitk, etc
      
  2) actually find the commit
      - git reflog (recent HEADs)
      - git fsck (lower level)
        git show --no-color 926eb3759b1fbce3afa2ee6fbd3917f57c9460f1 | mate
        
  3) recover the commit
    - git cherry-pick [ref]
      re-applies the [ref] commit in your current branch (it's a new commit since it has a new parent)
    - git diff --no-color [ref] > ../ohai.diff
      you can send that around before applying it
    - git merge / rebase
      in the simple scenarios

finding the introduction of a bug in a long timeline
  Git bisect does a binary search through between two commits you specify
  gotcha: if the command you run is in version control, the file may change as well from one commit to another. If that's the case, extract the file, or reproduce the bug in a simpler manner outside of git, so it's consistent across checkouts.

  Commands:
  git bisect start            # puts git in "bisect" mode. You can't commit or do anything else until "git bisect reset"
  git bisect good [commit id] # what's the last known good commit
  git bisect bad [commit id]  # what's the first commit where you 
  git bisect run [command]    # must return non-zero when the bug is present
  # Tweet about using git bisect while git does the heavy lifting.
  # ... once found, git displays a recap
  git bisect reset            # get back to normal state