If you've worked with Git long enough to wish you could modify the history of a repository, this talk is for you. Git's filter-branch command lets you re-write history in an automated way, changing usernames, removing certain commits, or restructuring repositories to have nested folders become the top level folder for potential use as submodules. Delivered on June 25, 2012

1. FILTER BRANCH
Pruning And Separating Git Repository History

2. @matthewmccull
matthew@github.com
github.com/training
matthewmccullough

3. The Command

4. Git Filter Branch

7. — Git Filter-Branch Man Page
Lets you rewrite git revision history by
rewriting the branches mentioned in the
<rev-list options>, applying custom
filters on each revision.
Those filters can modify each tree (e.g.
removing a file or running a perl rewrite
on all files) or information about each
commit.
Otherwise, all information (including
original commit times or merge
information) will be preserved.

8. Caution!
This re-creates new/different hashes
for all modified commits.

9. Caution!
This is effectively a new repository that
looks a lot like the old repository.

10. Modes

11. --env-filter

12. --tree-filter

13. --index-filter

14. --parent-filter

15. --msg-filter

16. --commit-filter

17. --tag-name-filter

18. --subdirectory-filter

19. Modes In Use

20. --env-filter

21. GIT_AUTHOR_NAME
GIT_AUTHOR_EMAIL
GIT_AUTHOR_DATE
GIT_COMMITTER_NAME
GIT_COMMITTER_EMAIL
GIT_COMMITTER_DATE

22. git filter-branch --env-filter 'export GIT_AUTHOR_NAME=Bonzo'

23. --tree-filter

24. git filter-branch --tree-filter 'rm BADFILE' HEAD
git filter-branch --tree-filter 'rm BADFILE' master
git filter-branch --tree-filter 'rm BADFILE' otherbranch
git filter-branch --tree-filter 'find . -iname b -exec rm {} ;'

25. --index-filter

26. much faster for rm

27. git filter-branch --index-filter 'git rm --cached --ignore-unmatch FILENAME' HEAD

28. --parent-filter

29. Graft in a different parent

30. --msg-filter

31. git filter-branch --msg-filter '
sed -e "/^git-svn-id:/d"
'

32. git filter-branch --msg-filter '
cat &&
echo "Signed-off-by Matthew McCullough"
' HEAD~5..HEAD

33. --commit-filter

34. Remove certain commits based on
commit contents

35. --tag-name-filter

36. Rename tags

37. --subdirectory-filter

38. git filter-branch --subdirectory-filter OLD -- --all

39. Options

40. --all

41. --prune-empty

42. --original

43. -d

44. --force

45. Closing and Q&A

46. support@github.com

47. github.com/training/free

48. FILTER BRANCH
Pruning And Separating Git Repository History