durrrrrenv

A zsh alternative to direnv that automatically loads environment configurations when you enter a directory.

Features

• Transparent zsh integration - Hooks into zsh to automatically check for .local_environment files
• Smart parent directory search - Automatically finds and loads parent directory environments when you cd deep into a project (limited to 5 levels for performance)
• Blazing fast - Sub-millisecond directory searches with zero-allocation fast path
• Automatic cleanup - Deactivates environments when you leave the directory
• Security-first - Requires explicit confirmation before executing any environment file
• File integrity checking - Detects when .local_environment files change and re-prompts for approval
• Simple syntax - Easy-to-understand commands for common tasks
• Performance monitoring - Built-in benchmark and verbose modes to measure overhead

Installation

Build from source

cargo build --release
sudo cp target/release/durrrrrenv /usr/local/bin/

Set up zsh integration

Add this to your ~/.zshrc:

eval "$(durrrrrenv hook)"

Usage

Creating a .local_environment file

Create a .local_environment file in your project directory with commands to execute:

# Example .local_environment
source ~/scripts/setup.sh
python_venv .venv
source <(west completion zsh)

Supported Commands

source <file>

Source a shell script file.

source ~/.bashrc
source ./scripts/setup.sh

python_venv [path]

Activate a Python virtual environment. Defaults to .venv if no path is provided.

python_venv           # Uses .venv
python_venv venv      # Uses venv directory

source <(command)

Process substitution - execute a command and source its output.

source <(west completion zsh)
source <(kubectl completion zsh)

Allowing a directory

When you cd into a directory with a .local_environment file for the first time, you'll see:

durrrrrenv: .local_environment file found but not allowed
durrrrrenv: Run 'durrrrrenv allow' to allow it
durrrrrenv: File contents:
---
source ~/setup.sh
python_venv .venv
---

To allow the file and execute it immediately:

eval "$(durrrrrenv allow)"

You'll be prompted to confirm:

Contents of .local_environment:
---
source ~/setup.sh
python_venv .venv
---
Allow this file to be executed? [y/N]: y
Allowed .local_environment in /home/user/project

The environment will be loaded immediately after you confirm. If you don't want to execute it immediately, just run durrrrrenv allow without the eval wrapper.

CLI Commands

durrrrrenv check

Check if the current directory has an allowed .local_environment file and execute it. This is called automatically by the zsh hook.

durrrrrenv check

durrrrrenv allow

Allow the .local_environment file in the current directory. After allowing, it outputs the shell script to stdout, which you can execute immediately with eval.

eval "$(durrrrrenv allow)"  # Allow and execute immediately
# or
durrrrrenv allow            # Just allow without executing

durrrrrenv deny

Remove permission for the .local_environment file in the current directory.

durrrrrenv deny

durrrrrenv status

Show the status of the current directory's .local_environment file.

durrrrrenv status

Output:

Directory: /home/user/project
Status: Allowed

Commands to execute:
  Source { path: "~/setup.sh" }
  PythonVenv { path: ".venv" }

durrrrrenv hook

Output the zsh hook script (used in eval "$(durrrrrenv hook)").

durrrrrenv bench

Benchmark the performance of directory search operations.

durrrrrenv bench                # Run 1000 iterations (default)
durrrrrenv bench -n 10000       # Run 10000 iterations

Output shows average time per search, searches per second, and search depth statistics.

durrrrrenv check --verbose

Check with detailed performance metrics.

durrrrrenv check --verbose

Shows search time, depth found, and total execution time.

Performance

durrrrrenv is designed for minimal overhead on every directory change:

• Fast parent directory search: Limited to 5 levels up (configurable in code via MAX_SEARCH_DEPTH)
• Zero-allocation fast path: Uses Path references instead of cloning PathBufs during search
• Early termination: Stops immediately when .local_environment is found or max depth reached
• Optimized zsh hook: Uses pure zsh built-ins (no external grep/sed/awk processes)
• Typical performance: Sub-millisecond search times on modern systems

Hook Optimizations:

• Fast-path file check: Searches for .local_environment in shell before spawning binary
• Subdirectory skip: No checks when moving within an already-active environment
• Zero external process spawns (no grep, head, cut, etc.)
• Pure zsh pattern matching with [[ ]] and parameter expansion
• Line-by-line processing using zsh array flags ${(@f)output}
• Early returns to avoid unnecessary processing

The hook only calls durrrrrenv check when:

1. You're not already in an active environment's subdirectory tree
2. A .local_environment file exists within 5 parent directories
3. Otherwise, it's pure zsh with instant response

Use durrrrrenv bench to measure performance on your system.

How It Works

1. When you cd into a directory, the zsh hook runs durrrrrenv check
2. If leaving a directory with an active environment:
   • Python venv is deactivated automatically
   • Environment is cleaned up
3. durrrrrenv check searches for a .local_environment file:
   • First checks the current directory
   • If not found, searches up the directory tree to find the nearest parent with a .local_environment file
   • This means you can cd directly into my-project/src/lib/utils/ and it will find and load my-project/.local_environment
4. If a .local_environment file is found:
   • If it's allowed and hasn't changed: commands are executed
   • If it's not allowed or has changed: you're prompted to allow it
5. Allowed directories are tracked in ~/.config/durrrrrenv/allowed.json
6. File contents are hashed to detect changes
7. Subdirectories inherit the parent's environment (no deactivation when entering subdirectories)

Security

• Explicit approval required - No environment file is executed without your confirmation
• Change detection - If a .local_environment file changes after being allowed, you'll be prompted again
• Transparent - Always shows you what will be executed before asking for approval

Configuration

Allowed directories are stored in: ~/.config/durrrrrenv/allowed.json

This file contains:

• Directory hashes (for privacy)
• Canonical paths
• File content hashes
• Timestamps

Example Workflow

# Create a new project
mkdir my-project
cd my-project

# Create a .local_environment file
cat > .local_environment << 'EOF'
python_venv .venv
source <(west completion zsh)
EOF

# On next cd, you'll be prompted
cd ..
cd my-project
# durrrrrenv: .local_environment file found but not allowed
# durrrrrenv: Run 'durrrrrenv allow' to allow it

# Allow it and execute immediately
eval "$(durrrrrenv allow)"
# Allow this file to be executed? [y/N]: y
# Allowed .local_environment in /home/user/my-project
# (.venv) is now activated and west completion is loaded immediately!

# It also auto-loads on cd
cd ..
# (.venv) is automatically deactivated when leaving!

cd my-project
# (.venv) is activated again

# Subdirectories keep the environment active
cd subdir
# (.venv) still active

cd ../..
# (.venv) deactivated when fully leaving the project

cd my-project
# Check status anytime
durrrrrenv status
# Directory: /home/user/my-project
# Status: Allowed

# Parent directory search - cd directly into deep subdirectory
cd /tmp
mkdir -p my-project/src/lib/utils
cd my-project/src/lib/utils
# (.venv) is activated! Searched up and found /tmp/my-project/.local_environment

PROVIDED BY AMERICAN EMBEDDED
Hardtech Consulting

Specialists in low power IoT design, wearable applications, high-speed applications.

build@amemb.com

License

MIT