# Rash - Bidirectional Shell Safety Tool
[](https://crates.io/crates/bashrs)
[](https://docs.rs/bashrs)
[](https://paiml.github.io/bashrs/)
[](LICENSE)
[](https://github.com/paiml/bashrs/actions)
[](https://github.com/paiml/bashrs/actions)
[](https://github.com/paiml/bashrs/actions)
**Rash** (v6.22.0) is a bidirectional shell safety tool that purifies legacy bash scripts and lets you write shell scripts in REAL Rust with automatic safety guarantees.
## 🚀 What's New in v6.22.0
**REPL Debugging Enhancements** - Released 2025-10-30
- **Call Stack Tracking**: Track function call hierarchy with `StackFrame` structs
- **Purification-Aware Debugging**: Compare original vs purified bash at breakpoints in real-time
- **Interactive Development**: See how bashrs transforms your scripts during debugging
See [CHANGELOG.md](CHANGELOG.md) for complete release notes.
## Why Rash?
- 🛡️ **Automatic Safety**: Protection against shell injection, word splitting, glob expansion
- 🔍 **Beyond Linting**: Full AST semantic understanding - **transforms** code, doesn't just warn
- 📦 **Zero Runtime Dependencies**: Generated scripts work on any POSIX shell
- 🎯 **Deterministic Output**: Same input always produces identical scripts
- ✅ **ShellCheck Compliant**: All output passes strict linting
### How Rash Exceeds ShellCheck
| ⚠️ **Warns**: "$RANDOM is non-deterministic" | ✅ **Rewrites** to version-based deterministic IDs |
| ⚠️ **Warns**: "mkdir may fail if exists" | ✅ **Transforms** to `mkdir -p` (idempotent) |
| ⚠️ **Warns**: "Unquoted variable expansion" | ✅ **Quotes** all variables automatically |
| Static pattern matching | **Full AST semantic understanding** |
| Detects issues (read-only) | **Fixes issues (read-write transformation)** |
**Key Difference**: ShellCheck tells you what's wrong. Rash **understands your code's intent** and rewrites it to be safe, deterministic, and idempotent — automatically.
## Quick Start
### Installation
```bash
# From crates.io (recommended)
cargo install bashrs
# Or from source
git clone https://github.com/paiml/bashrs
cd bashrs
cargo install --path rash
```
### Write Rust, Get Safe Shell
```rust
// install.rs
#[rash::main]
fn main() {
let version = env_var_or("VERSION", "1.0.0");
let prefix = env_var_or("PREFIX", "/usr/local");
echo("Installing MyApp {version} to {prefix}");
mkdir_p("{prefix}/bin");
mkdir_p("{prefix}/share/myapp");
if exec("cp myapp {prefix}/bin/") {
echo("✓ Binary installed");
} else {
eprint("✗ Failed to install binary");
exit(1);
}
}
```
**Transpile to safe POSIX shell**:
```bash
$ bashrs build install.rs -o install.sh
```
### Or Purify Existing Bash
**Before** (messy bash):
```bash
#!/bin/bash
SESSION_ID=$RANDOM # Non-deterministic
mkdir /app/releases/$RELEASE # Non-idempotent
rm /app/current # Fails if doesn't exist
```
**After** (purified by Rash):
```bash
#!/bin/sh
session_id="session-${version}" # ✅ Deterministic
mkdir -p "/app/releases/${release}" # ✅ Idempotent
rm -f "/app/current" # ✅ Safe removal
```
## Core Commands
```bash
# Transpile Rust to shell
bashrs build input.rs -o output.sh
# Purify legacy bash scripts
bashrs purify messy.sh -o clean.sh
# Interactive REPL with debugging
bashrs repl
# Lint shell scripts
bashrs lint script.sh
# Test bash scripts
bashrs test script.sh
# Quality scoring
bashrs score script.sh
# Comprehensive audit
bashrs audit script.sh
```
## 📚 Documentation
**The Rash Book** is the canonical source for all documentation:
### [**→ Read The Rash Book**](https://paiml.github.io/bashrs/)
**Quick links**:
- [Getting Started](https://paiml.github.io/bashrs/getting-started/installation.html)
- [Quick Start Tutorial](https://paiml.github.io/bashrs/getting-started/quick-start.html)
- [Linting Rules](https://paiml.github.io/bashrs/linting/security.html)
- [Configuration Management](https://paiml.github.io/bashrs/config/overview.html)
- [API Reference](https://docs.rs/bashrs)
**Why the book?**
- ✅ All examples automatically tested
- ✅ Always up-to-date with latest release
- ✅ Comprehensive coverage of all features
- ✅ Real-world examples and tutorials
## Quality Metrics (v6.22.0)
| **Quality Grade** | **A+ (Near Perfect)** ✅ |
| **Tests** | **5,465 passing** (0 failures) ✅ |
| **Coverage** | **88.71%** (exceeds 85% target) ✅ |
| **Mutation Testing** | **92% kill rate** ✅ |
| **Property Tests** | **52 properties** (~26k+ cases) ✅ |
| **ShellCheck** | **100% compliant** ✅ |
| **Shell Compatibility** | **sh, dash, bash, ash, zsh, mksh** ✅ |
## Shell Compatibility
Generated scripts are tested on:
| POSIX sh | - | ✅ Full support |
| dash | 0.5.11+ | ✅ Full support |
| bash | 3.2+ | ✅ Full support |
| ash (BusyBox) | 1.30+ | ✅ Full support |
| zsh | 5.0+ | ✅ Full support |
| mksh | R59+ | ✅ Full support |
## Performance
Rash is designed for fast transpilation:
- **Rust-to-Shell**: 21.1µs transpile time
- **Makefile Parsing**: 0.034-1.43ms (70-320x faster than targets)
- **Memory Usage**: <10MB for most scripts
## MCP Server
Rash provides a Model Context Protocol (MCP) server for AI-assisted shell script generation:
```bash
# Install MCP server
cargo install rash-mcp
# Run server
rash-mcp
```
Available in the official MCP registry as `io.github.paiml/rash`.
## Contributing
We welcome contributions! See our [Contributing Guide](CONTRIBUTING.md) for details.
```bash
# Clone and test
git clone https://github.com/paiml/bashrs.git
cd bashrs
make test
# Run all quality checks
make validate
```
## License
Rash is licensed under the MIT License. See [LICENSE](LICENSE) for details.
## Acknowledgments
Rash is built with safety principles inspired by:
- [ShellCheck](https://www.shellcheck.net/) for shell script analysis
- [Oil Shell](https://www.oilshell.org/) for shell language design
- The Rust community for memory safety practices
---
**For comprehensive documentation, tutorials, and examples, visit [The Rash Book](https://paiml.github.io/bashrs/).**