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Cherry-Pick & Bisect

Quick Summary

git cherry-pick copies a specific commit from one branch to another — like picking one cherry from the tree without taking the whole branch. git bisect performs a binary search through your commit history to find exactly which commit introduced a bug.

git cherry-pick​

When to Use​

  • Apply a hotfix from main to a release branch
  • Port a single commit without merging an entire branch
  • Recover a commit from a deleted branch

Syntax​

# Cherry-pick a single commit
git cherry-pick <commit-hash>

# Cherry-pick multiple commits
git cherry-pick <hash1> <hash2> <hash3>

# Cherry-pick a range (exclusive of first commit)
git cherry-pick A..B

# Cherry-pick without committing (stage only)
git cherry-pick --no-commit <hash>

# Abort a cherry-pick in progress
git cherry-pick --abort

Example​

# You're on main, and need a specific fix from feature branch
git log --oneline feature/auth
# d4e5f6a feat: add auth validation (← this one!)
# c3d4e5f feat: add auth UI
# b2c3d4e feat: add auth models

git checkout main
git cherry-pick d4e5f6a
[main e5f6a7b] feat: add auth validation
 1 file changed, 15 insertions(+)
Cherry-pick creates a NEW commit

The cherry-picked commit gets a new SHA hash on the target branch. If you later merge the source branch, Git may flag the duplicate change.

git bisect​

The Problem​

Your app worked last week but is broken now. You have 50 commits since then. Which commit broke it?

Without bisect: Test each commit manually (50 checks)
With bisect: Binary search (6 checks for 50 commits)

How It Works​

flowchart LR
    C1["C1 ✅"] --> C2["C2"] --> C3["C3"] --> C4["C4"] --> C5["C5 🐛"] --> C6["C6"] --> C7["C7 ❌"]
    
    style C1 fill:#4CAF50
    style C5 fill:#f44336
    style C7 fill:#f44336
# 1. Start bisect
git bisect start

# 2. Mark current commit as bad
git bisect bad

# 3. Mark a known good commit
git bisect good v1.0   # or a specific commit hash

# Git checks out the middle commit
# Bisecting: 25 revisions left to test (roughly 5 steps)
# 4. Test the code, then tell Git the result
git bisect good   # This commit works → bug is in later commits
# or
git bisect bad    # This commit is broken → bug is in earlier commits

# 5. Git narrows down and checks out the next middle commit
# Repeat step 4 until Git finds the exact commit

# 6. Git reports the first bad commit
# b2c3d4e is the first bad commit
# commit b2c3d4e
# Author: donnyaw
# Date: Mon Feb 10
# 
#     refactor: change auth token format

# 7. End bisect (go back to your branch)
git bisect reset

Automated Bisect​

If you have a test script that exits 0 for good and non-zero for bad:

git bisect start HEAD v1.0
git bisect run npm test
# Git automatically tests each commit and finds the culprit!

git bisect reset

Decision Guide​

What You WantCommand
Copy one commit to current branchgit cherry-pick <hash>
Copy commits without committinggit cherry-pick --no-commit <hash>
Find which commit introduced a buggit bisect start + good / bad
Automate bug findinggit bisect run <test-script>

Best Practices​

  • Prefer merge/rebase over cherry-pick — cherry-pick should be for exceptional cases
  • Use bisect with automated tests — eliminates human error in the search process
  • Always git bisect reset when done — returns you to your original branch
  • Document cherry-picked commits — note the source in the commit message

What's Next​

  1. Submodules & Subtrees — Include external repositories in your project
  2. Hooks & Automation — Automate tasks with Git hooks