mini-bash

mini-bash is a simple Unix shell designed as a learning and educational project. It supports a variety of basic shell functionalities including command execution, redirections, pipes, built-in commands, environment variable handling, and signal management. This project is primarily written in C, with a small portion of Makefile code for building the project.

Features

• Command Execution: mini-bash can execute built-in commands as well as external binaries available on the system.
• Redirections: The shell supports redirection of input and output, enabling users to run commands with files as input or output.
• Pipes: Users can chain commands together using pipes, passing the output of one command as the input to the next.
• Built-ins: The shell includes common built-in commands which are implemented directly in the program.
• Environment Variables: mini-bash reads and manages environment variables, which can be used within the shell or passed to executed programs.
• Signal Handling: The shell appropriately handles signals, making it robust against interruptions and ensuring smooth execution of background and foreground processes.

How It Works

1. Initialization: When mini-bash starts, it sets up the environment and initializes necessary variables and signal handlers.
2. Input Parsing: It reads user input and parses the command line to identify commands, arguments, and special symbols such as redirection operators or pipes.
3. Command Execution: Depending on whether the command is built-in or external, mini-bash either executes the command directly or spawns a child process to run an external binary.
4. Redirection & Pipes: The shell processes redirections and pipes by manipulating file descriptors, ensuring that data flows correctly between commands.
5. Signal Handling: Special attention is given to signal management, so that signals like SIGINT (Ctrl+C) are correctly interpreted, allowing the shell to maintain stable operation.

Building and Running

A Makefile is provided for easy compilation. To build the project, simply run:

make

Then, launch the shell with:

./mini-bash

Project Structure

• C Source Files: The bulk of the project is written in C, implementing the core shell functionalities.
• Makefile: Contains build instructions for compiling the project.

Conclusion

mini-bash is a compact and efficient implementation of a Unix shell. It serves as an excellent example of system programming in C and provides a hands-on approach to understanding shell mechanics.

Happy hacking!