Quick Start

This chapter will get you up and running with Rash in 5 minutes.

Your First Command

Let's start by checking the version:

bashrs --version

Linting a Shell Script

Create a simple shell script with a security issue:

cat > vulnerable.sh << 'EOF'
!/bin/bash
 Vulnerable script - uses eval with user input
read -p "Enter command: " cmd
eval "$cmd"
EOF

Now lint it with Rash:

bashrs lint vulnerable.sh

You'll see output like:

[SEC-001] Use of eval with user input can lead to command injection
  → Line 4: eval "$cmd"
  → Severity: Critical
  → Suggestion: Avoid eval or validate input strictly

Analyzing a Configuration File

Let's analyze a messy .bashrc file:

cat > messy-bashrc << 'EOF'
 Messy .bashrc with issues
export PATH="/usr/local/bin:$PATH"
export PATH="/opt/homebrew/bin:$PATH"
export PATH="/usr/local/bin:$PATH"  # Duplicate!

 Unquoted variables (security issue)
cd $HOME/my projects
EOF

Analyze it:

bashrs config analyze messy-bashrc

Output:

Analysis: messy-bashrc
  Type: Generic config file
  Lines: 7
  Complexity: 3/10

Issues Found: 2
  [CONFIG-001] Duplicate PATH entry at line 3
    → Path: /usr/local/bin
    → First seen: line 1
    → Suggestion: Remove duplicate entry

  [CONFIG-002] Unquoted variable expansion at line 6
    → Variable: $HOME
    → Can cause word splitting and glob expansion
    → Suggestion: Quote the variable: "${HOME}"

Purifying Configuration

Now let's fix these issues automatically:

bashrs config purify messy-bashrc --output clean-bashrc

The purified output (clean-bashrc):

 Messy .bashrc with issues
export PATH="/usr/local/bin:$PATH"
export PATH="/opt/homebrew/bin:$PATH"
 Duplicate! (removed by CONFIG-001)

 Unquoted variables (fixed by CONFIG-002)
cd "${HOME}/my projects"

Testing with mdbook

The examples in this book are automatically tested! Here's a Rust test example:

#![allow(unused)]
fn main() {
// This code is tested when building the book
fn purify_example() {
    let input = "export DIR=$HOME/projects";
    let expected = "export DIR=\"${HOME}/projects\"";

    // This would use the actual Rash library
    // assert_eq!(rash::config::quote_variables(input), expected);
}

#[test]
fn test_purify_example() {
    purify_example();
}
}

Common Workflows

1. Lint Before Commit

 Lint all shell scripts in project
find . -name "*.sh" -exec bashrs lint {} \;

2. CI/CD Integration

# .github/workflows/shellcheck.yml
name: Shell Lint
on: [push, pull_request]
jobs:
  lint:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - name: Install bashrs
        run: cargo install bashrs
      - name: Lint scripts
        run: bashrs lint scripts/*.sh

3. Purify Your dotfiles

 Analyze
bashrs config analyze ~/.bashrc

 Purify (dry-run by default)
bashrs config purify ~/.bashrc --output ~/.bashrc.purified

 Review changes
diff ~/.bashrc ~/.bashrc.purified

 Apply changes (creates backup automatically)
bashrs config purify ~/.bashrc --fix

What's Next?

Now that you've seen the basics, let's explore:

• Your First Purification: Step-by-step purification workflow
• Core Concepts: Understand determinism and idempotency
• Security Rules: Deep dive into security linting

Quick Reference

Troubleshooting

"bashrs: command not found"

Ensure ~/.cargo/bin is in your PATH:

export PATH="$HOME/.cargo/bin:$PATH"

Permission Denied

If you see permission errors:

chmod +x vulnerable.sh

Summary

In this chapter, you learned to:

• ✅ Lint shell scripts for security issues
• ✅ Analyze configuration files
• ✅ Purify config files automatically
• ✅ Integrate Rash into your workflow

Ready for a deeper dive? Continue to Your First Purification!