Systems Programming: Building a Unix-like Shell in Rust

Objective

This guide walks you through creating Mini-Shell, a Unix-like shell in Rust, covering command execution, piping, I/O redirection, built-in commands, background processes, and signal handling.

Step 1: Environment Setup

• Install Rust using rustup.
• Initialize the project with cargo new mini-shell.
• Include dependencies in Cargo.toml.

Suggested File Structure

mini-shell/
├── src/
│   ├── main.rs
│   ├── parser.rs
│   ├── executor.rs
│   └── utils.rs
├── tests/
├── Cargo.toml
└── README.md

Step 2: Implementing the Shell Loop

• Create a loop to display a prompt, read input, and handle the exit command.

Step 3: Executing External Commands

• Parse input commands into arguments.
• Implement process creation using fork().
• Execute commands with execvp() and wait for completion using waitpid().

Step 4: Built-in Commands (cd, exit)

• Handle cd using chdir().
• Implement exit with process termination.

Step 5: I/O Redirection (<, >)

• Parse and handle input/output redirection.
• Use open() and dup2() for file operations.

Step 6: Command Piping (|)

• Implement pipelines using pipe(), fork(), and dup2().
• Ensure correct redirection of input and output streams between commands.

Step 7: Background Execution (&)

• Support commands running in the background by detecting trailing &.

Step 8: Signal Handling

• Capture and handle signals such as Ctrl+C and Ctrl+D gracefully.

Step 9: Testing and Automation

• Write shell scripts in the tests/ directory to automate verification of shell behavior.

References

• Rust by Example
• Linux man pages
• MIT OS Course
• nix crate documentation

For complete code examples, detailed explanations, and full instructions, visit the original instructions document.