git - the stupid content tracker

This talk was presented to OTB on March 9th 2012. Check github.com/seenmyfate/git-presentation-demo for some source code goodness

Transcript

1. git the stupid content tracker
2. We know git right?
3. Things in git Things stored in git are objects Those objects have an ID That ID is a cryptographic hash of the components of that object
4. Things stored in git are objects blob - used to store file data tree - like a directory, references trees/blobs commit - points to a single tree
5. Those objects have an ID $ git rev-parse HEAD dca0d08ef9d55d4a024f870eb83adf715ebaeecc $ git rev-parse HEAD --short dca0d08
6. That ID is a hash of the components $ git ls-tree dca0d08 100644 blob 24c681c .gitignore 100644 blob 3f00574 .rvmrc 100644 blob 293cb17 Gemfile 100644 blob 8e4f0f0 Gemfile.lock $ git show 3f00574 rvm use 1.9.3@gitdemo --create
7. But we don't always have to use a sha
8. If all these things are true we're on our local master branch at commit 9ad544f we've pushed
9. Then all these are equivalent 9ad544f0736643f45434e33f20cde1fd9029e971 9ad544f origin/master refs/remotes/origin/master master refs/heads/master master@{0} HEAD
10. This is called a Treeish obviously
11. Treeish Date master@{yesterday} HEAD@{1 month ago}
12. Treeish Ordinal master@{2} HEAD@{4}
13. Treeish Tilde master~2 HEAD~4
14. Treeish Range 9ad544f..f3e9859c 9ad544f..HEAD~4 See also the less common Carrot, Tree Pointer and Blob..
15. so onto gitiquette Know what you're committing Know what you're not committing Commit with a well formed message Know what you're pulling Resolve conflicts with care
16. Know what you're committing $ git status $ git diff $ git diff --stat
17. Know what you're committing $ git add --all app $ git add --all lib/file.rb $ git add lib/file.rb -p
18. Know what you're committing $ git add -i
19. Know what you're not committing $ git stash $ git stash save "wip" $ git stash list $ git stash apply stash@{0}
20. Commit with a well formed message $ git commit -am "hack"
21. ┻━┻︵ヽ(`Д´)ﾉ︵┻━┻
22. Commit with a well formed message $ git config --global core.editor emacs $ git commit Follow @tpope's advice
24. But we all forget things
25. FIFY Commit with a well formed message $ git commit --amend
26. Rewrite history Commit with a well formed message $ git commit -m "RT1234..." ..realise you forgot something.. $ git commit -m "fixup! RT1234" Then autosquash your last 2 commits $ git rebase --autosquash HEAD~2
27. use the force $ git push origin +my_branch $ git push origin my_branch --force
28. Never change public history or people will hate you
29. Know what you're pulling $ git log origin/master -p $ git fetch origin $ git whatchanged $ git log --graph --oneline
30. Rebase Workflow never commit directly to master update master using git pull origin master rebase your feature branch from your local master
31. Rebase if I branch when master is at B 1---2---3 #my_branch / A---B #master and our branches diverge 1---2---3 #my_branch / A---B--C--D--E--F #master
32. Rebase Rebase replays my changes onto current master 1---2---3 #my_branch / A---B--C--D--E--F #master So it's as if I branched today No merge bubble No messy history
33. My workflow Never work or commit directly to master use branches for everything rebase feature branches from master squash working commits to one single feature commit merge this feature into master via a release branch
34. For example $ git pull origin master $ git checkout -b feature/my_branch ..work / commit.. $ git checkout master $ git fetch origin $ git pull origin master $ git checkout feature/my_branch $ git rebase -i master ..work / commit..
35. keep it clean $ git push origin :release/my_branch $ git branch -D release/my_branch
36. only ever push one branch $ git push origin will push all changes on the local branches that have matching remote branches at origin $ git push origin my_branch
37. ~/.zshrc function current_branch() { ref=$(git symbolic-ref HEAD 2> /dev/null) || return echo ${ref#refs/heads/} } alias ggpush='git push origin $(current_branch)' alias ggpull='git pull origin $(current_branch)'
38. $ git clone git@github.com:seenmyfate/git_demo.git
39. one liners $ git show-ref --heads see if your branches are up to date $ git log --pretty=oneline -S'massive_fail' search for when someone added the term to the repo $ git blame test/functional/posts_controller_test.rb the precursor to git punch $ git grep -c -n <term/regexp> $(git rev-list --all) search historically for a term or rgexp $ git log --graph historic graph goodness $ git log --all -M -C --name-only --format='format:' \ "$@" | sort | grep -v '^$' | uniq -c | sort | \ awk 'BEGIN {print "count\tfile"} {print $1 "\t" $2}' churn
40. config $ git config --global help.autocorrect 1 $ git commint WARNING: You called a Git command named 'commint', which does not exist. Continuing under the assumption that you meant 'commit'
41. $ git config --global color.ui true
42. $ git config --global core.whitespace trailing-space $ git rebase --whitespace=fix HEAD~1
43. Bisect $ git bisect start $ git bisect good 85d026e $ git bisect bad 6a24cd3 $ git bisect run rake $ git show $ git bisect reset
44. Further reading: man git http://progit.org/book/ http://book.git-scm.com/index.html https://github.com/github/gitignore http://marklodato.github.com/visual-git-guide/index-en.html http://tbaggery.com/2008/04/19/a-note-about-git-commit- messages.html tom-clements.com | github.com/seenmyfate @Seenmyfate