Understanding the Tilde (~) Operator in Git

In the last blog, we explored how to time travel in Git by switching to specific commits. In this one, let’s dive into a powerful operator that helps us move relative to HEAD without needing to copy-paste commit IDs: the tilde (~) operator.

Setup Example

Suppose we created a repository with three commits:

git init project9
cd project9

echo "first" > file.txt
git add .
git commit -m "First commit"

echo "second" >> file.txt
git commit -am "Second commit"

echo "third" >> file.txt
git commit -am "Third commit"

Check history:

git log --oneline

Output:

61f19cb Third commit
2699422 Second commit
a1b2c3d First commit

Using git rev-parse with HEAD

To print the commit ID of HEAD:

git rev-parse HEAD

Output:

61f19cb...

Moving Back with ~

The tilde operator lets you move up the ancestry chain:

git rev-parse HEAD~1

Output:

2699422...

This is the first parent (previous commit).

git rev-parse HEAD~2

Output:

a1b2c3d...

This is the grandparent (two commits behind HEAD).

And so on:

  • HEAD~0 → current commit (same as HEAD)
  • HEAD~1 → parent commit
  • HEAD~2 → grandparent
  • HEAD~3 → great-grandparent

With Merges

In a linear history, HEAD~n is straightforward. But what if there’s a merge commit?

Here:

  • HEAD~1 = the first parent (usually main)
  • HEAD~2 = the parent of the first parent (grandparent)

⚡ But how do we access the other parent of a merge? That’s where the caret (^) operator comes in — which we’ll cover in the next blog.

Summary

  • git rev-parse prints commit IDs for references.
  • The tilde (~) operator moves back in the ancestry chain.
  • HEAD~1 = parent, HEAD~2 = grandparent, etc.
  • Useful for git diff, git log, git show, or any command that accepts commit IDs.
  • In merges, ~ follows the first parent chain only.

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