Unix Shell

🔍 Problem Statement

In this project, I implemented a Unix shell called wsh, capable of running both interactive and batch modes. The shell supports:

• Built-in commands: exit, cd, local, export, and vars.
• Process execution: Using fork() and execv() to run external programs.
• Input/output redirection: Handling < and > for file-based input and output.
• Environment and shell variables: Supporting local and exported variables.
• Script execution: Running scripts with #!./wsh.

The project required careful command parsing, process management, and memory safety checks, ensuring that wsh behaves similarly to a standard Unix shell.

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🎯 What I Learned

This assignment provided valuable experience in systems programming and shell design. Key takeaways include:
✅ Process creation and execution – Using fork() and execv() to manage child processes.
✅ File redirection – Implementing < and > to manipulate stdin and stdout.
✅ Shell variable handling – Managing local and environment variables correctly.
✅ Script execution – Understanding how the shell interprets and runs script files.
✅ Memory safety and debugging – Avoiding memory leaks and ensuring robust error handling.

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🏆 Results

I successfully implemented all required features of wsh, passing all test cases, and received 100% on the assignment. This project strengthened my understanding of process control, shell internals, and Unix system programming.

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📟 How to Run

To run this shell, simply clone this repository to anywhere on your computer and run ./wsh. (You need to be in a unix environment or running bash, zsh, or something similar).

Once you've ran the shell, then you can do whatever there is to do on your previous shell!

[hdoll@royal-22] (33)$ ./wsh
wsh> echo hello world
hello world
wsh>