Mini Shell

A Unix-like command-line shell built from scratch in C using Linux system calls.

Features

• Execute external commands (ls, cat, grep, date, sleep, etc.)
• Built-in commands: cd, pwd, echo, exit, jobs, fg, bg
• Piping between multiple commands: ls -l | grep main | wc -l
• Background execution using &
• Job control — suspend with Ctrl+Z, resume with fg/bg
• Signal handling — SIGINT, SIGTSTP, SIGCHLD
• Custom prompt rename using PS1=
• Auto-cleanup of background zombie processes via SIGCHLD

Technologies Used

• Language: C
• OS: Linux (Ubuntu)
• Concepts: fork(), exec(), waitpid(), pipe(), dup2(), signals, linked list

How to Compile

make

How to Run

./shell

Usage Examples

myshell$: ls -l
myshell$: ls -l | wc
myshell$: sleep 30 &
myshell$: jobs
myshell$: fg
myshell$: PS1=suchi$:
myshell$: cd /home
myshell$: echo $$
myshell$: cat file.txt | grep hello | wc -l

Project Structure

File	Purpose
main.c	Global variables and entry point
scan_input.c	Main shell loop, fork, signal handler
commands.c	Command classification and execution
linked_list.c	Job table for background and stopped processes
header.h	All declarations and includes
ext_cmds.txt	List of supported external commands