code-runner

This skill enables you to run code snippets in multiple programming languages directly from the command line.

When to Use This Skill

Use this skill when:

• The user wants to run or execute a code snippet
• Testing algorithm implementations or logic
• Verifying expected output of code
• Running quick scripts or one-liners
• Checking syntax or runtime behavior
• Demonstrating code functionality

Supported Languages

The following languages are supported (requires the interpreter/compiler to be installed):

| Language | Command | File Extension | |----------|---------|----------------| | JavaScript | node | .js | | TypeScript | ts-node | .ts | | Python | python | .py | | Java | java (compile & run) | .java | | C | gcc (compile & run) | .c | | C++ | g++ (compile & run) | .cpp | | Go | go run | .go | | Rust | rustc (compile & run) | .rs | | Ruby | ruby | .rb | | PHP | php | .php | | Perl | perl | .pl | | Lua | lua | .lua | | R | Rscript | .r | | Swift | swift | .swift | | Kotlin | kotlin | .kts | | Scala | scala | .scala | | Groovy | groovy | .groovy | | Dart | dart | .dart | | Julia | julia | .jl | | Haskell | runhaskell | .hs | | Clojure | clojure | .clj | | F# | dotnet fsi | .fsx | | C# | dotnet script | .csx | | PowerShell | pwsh | .ps1 | | Bash | bash | .sh | | Batch | cmd /c | .bat | | CoffeeScript | coffee | .coffee | | Crystal | crystal | .cr | | Elixir | elixir | .exs | | Nim | nim compile --run | .nim | | OCaml | ocaml | .ml | | Racket | racket | .rkt | | Scheme | scheme | .scm | | Lisp | sbcl --script | .lisp |

See references/LANGUAGES.md for detailed language configuration.

How to Run Code

Step 1: Identify the Language

Determine the programming language from:

• User's explicit request (e.g., "run this Python code")
• File extension if provided
• Code syntax patterns

Step 2: Execute Using the Runner Script

⚠️ Important for AI Agents: Use stdin to avoid escaping issues with quotes, backslashes, and special characters.

Recommended Method (stdin):

echo "<code>" | node scripts/run-code.cjs <languageId>

Alternative Method (CLI argument - for simple code only):

node scripts/run-code.cjs <languageId> "<code>"

Example - JavaScript:

echo "console.log('Hello, World!')" | node scripts/run-code.cjs javascript

Example - Python:

echo "print('Hello, World!')" | node scripts/run-code.cjs python

Example - Java (multi-line):

echo "public class Test {
    public static void main(String[] args) {
        System.out.println(\"Hello from Java!\");
    }
}" | node scripts/run-code.cjs java

Example - Multi-line code from variable:

# In bash
CODE='import math
print("Pi:", math.pi)
print("Result:", math.factorial(5))'
echo "$CODE" | node scripts/run-code.cjs python

# In PowerShell (inline here-string)
@"
import math
print("Pi:", math.pi)
print("Result:", math.factorial(5))
"@ | node scripts/run-code.cjs python

Step 3: Return Results

• Show the output (stdout) to the user
• If there are errors (stderr), explain what went wrong
• Suggest fixes for common errors

Platform Notes

Windows

• Use cmd /c for batch scripts
• PowerShell scripts require pwsh or powershell
• Path separators use backslash \

macOS / Linux

• Bash scripts work natively
• Swift available on macOS
• Use #!/usr/bin/env shebang for portable scripts

Error Handling

Common issues and solutions:

1. Command not found: The language interpreter is not installed or not in PATH

   • Suggest installing the required runtime
   • Provide installation instructions

2. Syntax errors: Code has syntax issues

   • Show the error message
   • Point to the line number if available

3. Runtime errors: Code runs but fails during execution

   • Display the stack trace
   • Explain the error type

4. Timeout: Code takes too long (default: 30 seconds)

   • Warn about infinite loops
   • Suggest optimizations

Security Considerations

⚠️ Important: Running arbitrary code can be dangerous. Always:

1. Review the code before execution
2. Be cautious with code that:
   • Accesses the file system
   • Makes network requests
   • Executes system commands
   • Modifies environment variables
3. Consider running in a sandboxed environment for untrusted code

Examples

Example 1: Run a JavaScript calculation

echo "console.log(Array.from({length: 10}, (_, i) => i * i))" | node scripts/run-code.cjs javascript

Output: [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]

Example 2: Run Python with imports

echo "import math; print(math.factorial(10))" | node scripts/run-code.cjs python

Output: 3628800

Example 3: Test a Go function

echo 'package main; import "fmt"; func main() { fmt.Println("Hello from Go!") }' | node scripts/run-code.cjs go

Output: Hello from Go!