Minishell: As beautiful as a shell

Overview

Minishell is a simplified bash implementation written in C. It is designed to demonstrate mastery of process creation, synchronization, file descriptor management, and signal handling.

The project involves building a shell that can interpret and execute commands, handle pipes and redirections, and manage environment variables, mimicking the behavior of the popular bash shell.

Installation

Prerequisites

• GCC or Clang compiler
• make
• readline library

# Install readline on Linux (Ubuntu/Debian)
sudo apt-get install libreadline-dev

Compilation

The project utilizes a Makefile to manage the build process.

Command	Action
make	Compiles the minishell executable.
make clean	Removes object files.
make fclean	Removes object files and the executable.
make re	Recompiles the project from scratch.

Usage

1. Start the Shell

Run the executable to start the shell session.

./minishell

2. Execute Commands

You can run commands just like in a standard bash shell.

minicecco:/home/s/Minishell> ls -la
minicecco:/home/s/Minishell> grep "int" main.c | wc -l
minicecco:/home/s/Minishell> echo "Hello 42" > hello.txt

Features & Implementation

Technical Architecture

• Parsing: Tokenizes input, handles quotes (' and "), and expands environment variables.
• Execution: Uses fork(), execve(), and waitpid() to execute commands.
• Pipes: Implements inter-process communication using pipe() and dup2().
• Signals: Handles Ctrl-C, Ctrl-D, and Ctrl-\ to mimic bash behavior.

Built-in Commands

The shell includes its own implementation of the following built-ins:

• echo (with -n)
• cd (relative and absolute paths)
• pwd
• export
• unset
• env
• exit

Redirections

Supports standard input/output redirections:

• < : Input redirection
• > : Output redirection
• << : Here-document
• >> : Append output