Custom Linux Shell

A Unix shell built from scratch in C++, implementing core shell functionality including command parsing, process creation, and child process management using POSIX system calls.

Features

• Execute standard Linux commands (e.g. ls, pwd, cd, echo)
• Fork/exec model for child process creation
• Custom ChildProcess class for process lifecycle management
• Graceful handling of invalid commands and error states
• Clean prompt loop with exit support

How It Works

The shell runs a read-eval-print loop (REPL):

1. Displays a prompt and reads user input
2. Parses the command and arguments
3. Forks a child process using fork()
4. Executes the command in the child via execvp()
5. Parent process waits for the child to finish before prompting again

The ChildProcess class encapsulates the forking and execution logic, keeping the main shell loop clean and readable.

Build & Run

Requirements: Linux or WSL, g++ (C++11 or later)

g++ -o shell customLinuxShell.cpp ChildProcess.cpp
./shell

Example

$ ./shell
> ls
ChildProcess.cpp  ChildProcess.h  customLinuxShell.cpp  README.md
> echo hello world
hello world
> exit

What I Learned

Building this project gave me hands-on experience with:

• POSIX process management (fork, execvp, waitpid)
• Low-level C++ memory and string handling
• Separating concerns with class-based design in systems code