git_commits_and_refs

git commits and refs

Understanding commits and references.

📝 Commit Structure

A commit contains:

• Tree (snapshot)
• Parent(s)
• Author
• Committer
• Message

View Commit Details

git cat-file -p HEAD

Shows full commit object.

🏷️ Reference Types

📊 Reference Diagram

graph LR
    A[HEAD] --> B[refs/heads/main]
    B --> C[commit abc123]
    D[refs/heads/feature] --> E[commit def456]
    F[refs/tags/v1.0] --> C

🔍 View References

Show HEAD

cat .git/HEAD

Shows what HEAD points to.

Show Branch Ref

cat .git/refs/heads/main

Shows commit hash of main branch.

Show All Refs

git show-ref

Lists all references.

Resolve Reference

git rev-parse HEAD

Shows full commit hash.

Resolve to Short Hash

git rev-parse --short HEAD

Shows short commit hash.

📍 Reference Syntax

Direct Reference

git show main

Shows main branch tip.

Parent Reference

git show HEAD~1

Shows parent of HEAD.

Grandparent

git show HEAD~2

Shows 2 commits before HEAD.

First Parent (Merge)

git show HEAD^1

First parent of merge commit.

Second Parent (Merge)

git show HEAD^2

Second parent (merged branch).

By Date

git show main@{yesterday}

Shows main as of yesterday.

By Reflog Index

git show HEAD@{5}

Shows HEAD from 5 moves ago.

📋 Commit Ranges

Commits in B not in A

git log A..B

Shows commits reachable from B but not A.

Commits in Either

git log A...B

Shows commits in A or B but not both.

🔧 Update References

Update Branch Ref

git update-ref refs/heads/main abc1234

Manually updates branch to commit.

Delete Reference

git update-ref -d refs/heads/old-branch

Removes a reference.

💡 Tips

git symbolic-ref HEAD

🔗 Related

• Git Objects
• Detailed History
• reflog

#git #commits #refs #internals