Advanced git usage

1. Fancy Git
Liu Lin

2. How to modify
what you have committed?

3. 1.Chang the Last Commit

4. ❖ git commit --amend
C1 C2 C3 C4 C5
master
HEAD
C5’
master
HEAD

5. 2.Chang Multiple Commit Message

6. C1 C2 C3 C4 C5 C6
❖ Change Message
pick C4 add a.file
pick C5 add first line
pick C6 add second line
Rebase C3..C6 onto C3
edit C4 add a.file
pick C5 add first line
pick C6 add second line
Rebase C3..C6 onto C3
master
HEAD
git rebase -i C3

7. C1 C2 C3 C4 C5 C6
❖ Change Message
add a.file
git commit --amend
change c4 message
C4’ C5’ C6’git rebase --continue
HEAD master
HEAD
master
HEAD

8. 3.Reorder Commits

9. C1 C2 C3 C4 C5 C6
pick C4 add a.file
pick C5 add first line
pick C6 add second line
Rebase C3..C6 onto C3
pick C5 add first line
pick C4 add a.file
Rebase C3..C6 onto C3
❖ Reorder Commits
C5’ C4’
git rebase -i HEAD~3
master
HEAD

10. 4.Squash Commits

11. C1 C2 C3 C4 C5 C6
pick C5 add first line
pick C6 add second line
Rebase C4..C6 onto C4
pick C5 add first line
squash C6 add second line
Rebase C4..C6 onto C4
❖ Squash Commits
master
HEAD
git rebase -i HEAD~2

12. C1 C2 C3 C4 C5 C6
# This s a combination of 2 commits.
# The first commit's message is:
add first line
# This is the 2nd commit message:
add second line
❖ Squash Commits
C5C6’
master
HEAD
master
HEAD
tree c9cb48
parent C4
add first line
add second line
git cat-file -p C5’

13. 5.Split a Commit

14. C1 C2 C3 C4 C5 C6
❖ Split a Commit
pick C5 add first line and b.file
pick C6 add second line
Rebase C4..C6 onto C4
edit C5 add first line and b.file
pick C6 add second line
Rebase C4..C6 onto C4
master
HEAD
git rebase -i C4

15. C1 C2 C3 C4 C5 C6
❖ Split a Commit
HEAD master
git reset HEAD~1
a.file
b.file
C5-1
git commit -m ‘add a.file’
git commit -m ‘add b.file’
HEAD
C5-2

16. C1 C2 C3 C4 C5 C6
❖ Split a Commit
master
C5-1
HEAD
C5-2 C6’
git rebase --continue
master
HEAD

17. How to modify
what you have pushed?

18. C1 C2 C3 C4 C5 -C5
❖ git revert C5
master
HEAD
origin/master
- This is the one line
- This is the two line
Diff

19. ❖ git push --force
C1 C2 C3
C1 C2 C3
R4
origin/master
master
L4
L4
origin/master
Local Repo
Remote Repo

20. ❖ git reflog show remotes/origin/master
L4 remotes/origin/master@{0} : update by push
R4 remotes/origin/master@{1} : update by push
C3 remotes/origin/master@{2} : update by push
C2 remotes/origin/master@{3} : update by push
C1 remotes/origin/master@{4} : update by push
C1 C2 C3 R4
L4
origin/master
Remote Repo

21. ❖ git checkout -b temp R4
C1 C2 C3
origin/master
master
L4
Local Repo
R4
HEAD
temp

22. ❖ git push --force origin temp:master
C1 C2 C3
C1 C2 C3
R4
origin/master
master
L4
L4
origin/master
Local Repo
Remote Repo
R4tempHEAD

23. How to deal with
a detached HEAD?

24. C1 C2 C3 C4 C5 C6
❖ git checkout -b new
master
HEAD
B1
HEAD
new

25. How to find
the commit you lose?

26. ❖ git reflog
Git Repo
logs
HEAD
refs
heads
master
remotes
origin
master
HEAD
branch1
git reflog show HEAD
git reflog show master
git reflog show remotes/origin/master

27. ❖ git cherry-pick B2
C1 C2 C3 C4 C5
master
HEAD
B2’
B1 B2 B3
fix

28. The Premiums

29. ❖ git rebase --onto master fix1 fix2
C1 C2 C3 A1’ A2’
master
HEAD
B1 B2 B3
fix1
A1 A2
fix2

30. Thanks!