shellhook is a utility for Nix development shells that displays environment information and creates a pre-push git hook to run nix flake check.
Installation
Add to your flake
devShells.default = pkgs.mkShell {
shellHook = pkgs.trev.shellhook.ref;
};
Complete example
{
inputs = {
nixpkgs.url = "github:nixos/nixpkgs/nixpkgs-unstable";
trev = {
url = "github:spotdemo4/nur";
inputs.nixpkgs.follows = "nixpkgs";
};
};
outputs = { nixpkgs, trev, ... }:
trev.libs.mkFlake (system:
let
pkgs = import nixpkgs {
inherit system;
overlays = [
trev.overlays.packages
trev.overlays.libs
];
};
in
{
devShells.default = pkgs.mkShell {
packages = with pkgs; [
nixfmt
prettier
];
shellHook = pkgs.trev.shellhook.ref;
};
}
);
}
Features
When entering a development shell, shellhook displays:
- Current Nix version
- Available packages in the shell
- Active overlays
- Environment variables
- Git repository status
Pre-push git hook
Automatically creates a .git/hooks/pre-push hook that:
- Runs
nix flake check before pushing
- Prevents pushes if checks fail
- Ensures code quality and build success
Example output
When entering the dev shell:
🔨 Nix Development Shell
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Nix version: 2.18.1
System: x86_64-linux
Packages:
• nixfmt-rfc-style 0.5.0
• prettier 3.1.0
Pre-push hook installed ✓
Run 'nix flake check' before pushing
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Pre-push hook behavior
Automatic installation
The hook is created automatically when entering the dev shell. If a hook already exists, it’s backed up to .git/hooks/pre-push.backup.
Hook execution
When you run git push, the hook:
#!/usr/bin/env bash
set -e
echo "Running nix flake check..."
nix flake check
if [ $? -ne 0 ]; then
echo "❌ Flake checks failed. Push aborted."
exit 1
fi
echo "✓ All checks passed"
Skip the hook
To bypass the pre-push check when needed:
Only use --no-verify when absolutely necessary. The pre-push hook prevents broken code from reaching your repository.
Customization
Combine with other hooks
Add your own shell initialization:
devShells.default = pkgs.mkShell {
shellHook = ''
${pkgs.trev.shellhook.ref}
# Your custom initialization
echo "Welcome to my project!"
export PROJECT_ROOT=$(pwd)
'';
};
Disable pre-push hook
If you only want the environment info without the git hook:
devShells.default = pkgs.mkShell {
shellHook = ''
${pkgs.trev.shellhook.ref}
rm -f .git/hooks/pre-push
'';
};
Use with direnv
Combine with direnv for automatic shell activation:
When you cd into the project directory, direnv automatically loads the dev shell with shellhook.
Benefits
Quality assurance
Prevent broken code from being pushed to your repository
Environment visibility
See exactly what’s available in your development environment
Team consistency
Ensure all developers run the same checks before pushing
Early detection
Catch build failures before they reach CI/CD
Source code
View the shellhook implementation: pkgs/shellhook/shellhook.sh
Use shellhook in all your Nix projects to maintain consistent development practices and catch issues early.
Links
