Git Merge, Rebase, Cherry-pick, and Stash

Git Merge

git merge combines changes from one branch into another. It creates a new merge commit that ties together the histories of both branches (unless a fast-forward is possible).

Types of Merge

Fast-forward merge — happens when the target branch has no new commits since the feature branch was created. Git simply moves the pointer forward.

Three-way merge — happens when both branches have diverged (have new commits). Git creates a new merge commit with two parents.

Example

# Start on main
git checkout main

# Merge feature branch into main
git merge feature-login

Before merge:

main:     A---B---C
                    \
feature:             D---E

After merge (three-way):

main:     A---B---C-------M
                    \     /
feature:             D---E

Common flags

git merge --no-ff feature-login   # force a merge commit even if fast-forward is possible
git merge --abort                 # cancel a merge in progress (e.g., during conflicts)
git merge --squash feature-login  # combine all feature commits into one, staged but not committed

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Git Rebase

git rebase moves or replays commits from one branch onto another. Instead of creating a merge commit, it rewrites history so your commits appear as if they were made on top of the target branch.

Example

git checkout feature-login
git rebase main

Before rebase:

main:     A---B---C
                    \
feature:             D---E

After rebase:

main:     A---B---C
                    \
feature:             D'---E'

Note: D' and E' are new commits with new hashes — the original D and E are replaced.

Interactive Rebase

Used to edit, squash, reorder, or drop commits before they’re shared.

git rebase -i HEAD~3

This opens an editor listing the last 3 commits:

pick a1b2c3 Add login form
pick d4e5f6 Fix typo
pick g7h8i9 Add validation

Common actions:

• pick — keep commit as is
• squash (or s) — combine with previous commit
• reword (or r) — edit commit message
• drop (or d) — remove commit

Git Cherry-pick

git cherry-pick applies a specific commit from one branch onto another, without merging the entire branch.

Example

# You're on main, and want commit e5f6g7 from feature-login
git checkout main
git cherry-pick e5f6g7

Before:

main:     A---B---C
                    \
feature:             D---E---F
                          ^
                   (want only E)

After:

main:     A---B---C---E'

Common flags

git cherry-pick e5f6g7 g8h9i0     # cherry-pick multiple commits
git cherry-pick --continue        # after resolving a conflict
git cherry-pick --abort           # cancel the cherry-pick
git cherry-pick -n e5f6g7         # apply changes without committing (stage only)

Use Case

A hotfix was committed to a release branch, and you want that same fix in main without merging all of release’s other commits.

gitexercises

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Quick Reference Summary

Command	Purpose
git merge <branch>	Combine two branches’ histories, creating a merge commit
git rebase <branch>	Replay commits onto another branch for linear history
git rebase -i	Edit, squash, reorder, or drop commits interactively
git cherry-pick <commit>	Apply a single commit from elsewhere onto current branch