update-nixpkgs-unstable

name	update-nixpkgs-unstable
description	Update nixpkgs-unstable reference in flake.nix to latest commit

Update nixpkgs-unstable

Overview

Update pinned nixpkgs-unstable commit to latest upstream.

This skill documents the process for updating the unstable nixpkgs reference from a pinned commit hash to the current HEAD of nixpkgs-unstable branch.

When to Use

• Updating flake.nix to latest nixpkgs-unstable
• Running git ls-remote to fetch commit hash
• Commit changes (but dont push them)
• Triggering macOS rebuild with darwin-rebuild

Process

┌─────────────────┐
│ 1. Fetch latest │
│    commit hash  │
└────────┬────────┘
         │
         ▼
┌─────────────────┐
│ 2. Update       │
│    flake.nix    │
└────────┬────────┘
         │
         ▼
┌─────────────────┐
│ 3. Commit       │
└────────┬────────┘
         │
         ▼
┌─────────────────┐
│ 4. Run sudo     │
│    darwin-rebuild│
└─────────────────┘

Quick Reference

Step	Command	Purpose
Fetch hash	git ls-remote https://github.com/NixOS/nixpkgs.git refs/heads/nixpkgs-unstable | cut -f1	Get latest commit
Update flake	Edit line with nixpkgs-unstable-*.url	Replace old hash
Commit	git add flake.nix && git commit -m "chore: update nixpkgs-unstable to \<hash\>"	Stage & commit
Rebuild	sudo darwin-rebuild switch --flake $HOME/code/nixos-dotfiles#cyan	Apply to macOS

Implementation

Step 1: Fetch Latest Commit

git ls-remote https://github.com/NixOS/nixpkgs.git refs/heads/nixpkgs-unstable | cut -f1

Output: <some new commit hash> (example value only)

Step 2: Update flake.nix

Edit the flake.nix file at line 7 (where nixpkgs-unstable is defined):

Before:

nixpkgs-unstable-2611.url = "github:NixOS/nixpkgs/<old commit hash>";

After:

nixpkgs-unstable-2611.url = "github:NixOS/nixpkgs/<some new commit hash>";

Step 3: Commit Changes

git add flake.nix
git commit -m "chore: update nixpkgs-unstable"

Common Mistakes

Mistake	Fix
Forgetting to stage file	Run git add flake.nix before commit
Copying incomplete hash	Verify hash is 40 characters (full SHA)