Shells like Bash, Zsh, and Fish are the primary interface between users and operating systems, enabling command execution, file manipulation, and system resource access. Understanding how shells work under the hood is fundamental for systems programming, revealing how processes are created, how command-line interfaces parse input, and how system calls interact with the kernel. Building a shell from scratch demonstrates core concepts in operating systems, process management, and low-level programming that apply to any system-level software development.
In this project, we'll build a functional Unix shell in C programming that implements common commands and enables program execution. We'll start by creating a command prompt that accepts user input and processes commands, then implement basic shell control commands like exit and clear. Next, we'll build built-in commands for output operations (echo, cat) and directory manipulation (pwd, cd, ls, mkdir, touch), utilizing C library functions and system calls like fork(), exec(), and chdir() for process creation and file system operations. We'll add file management commands (rm, rmdir, mv) and a help command for user guidance.
Finally, we'll implement executable program support, allowing users to run any binary on the system by creating child processes and handling program execution through the shell. By the end, you'll have a working command-line shell demonstrating C systems programming, Unix system calls, process management, file system APIs, and command parsing applicable to any operating systems development or low-level software engineering project.