Minishell - A Bash Replica in C

Welcome to Minishell, a minimalist yet powerful replica of the Unix Bash shell, entirely written in C. This project aims to simulate the core functionalities of a Unix-like command-line interface, providing a deeper understanding of shell behavior, process management, and system calls.

Features

Minishell supports several key functionalities:

• Basic Command Execution: Run common commands such as ls, cat, echo, etc., just like in a standard shell.
• Built-in Commands: Implementations for built-in commands like cd, pwd, export, unset, and exit.
• Redirections and Pipes: Input/output redirections (>, <, >>) and pipes (|) to chain commands.
• Environment Variables: Dynamic handling of environment variables, allowing variable expansion and management.
• Signal Handling: Graceful handling of Ctrl+C, Ctrl+D, and Ctrl+\ to mimic terminal signals.
• Command History: Maintains a history of previously executed commands.
• Support for Executable Files: Run external programs, including compiled executables, directly from the shell.
• Path Resolution: Smart resolution of command paths for seamless execution.

Getting Started

Prerequisites

To run the project, you'll need a Unix-like operating system (Linux/macOS) with the following installed:

• GCC or another compatible C compiler
• GNU Make

Installation

1. Clone the repository:

   git clone https://github.com/Nilufergul/minishell

2. Navigate to the project directory:

   cd minishell

3. Build the project:

   make

4. Run the shell:

   ./minishell

Usage

Once you're inside minishell, you can start typing commands as you would in any Unix shell. Below are a few examples:

• Change Directory:

  cd /path/to/directory

• List Files:

  ls -la

• Redirection:

  echo "Hello, Minishell!" > output.txt

• Piping:

  cat file.txt | grep "search_term"

• Execute a Program:

  ./a.out

• Environment Variables:

  export MYVAR="Hello"
  echo $MYVAR

• Exit:

  exit

Example Session

$ ./minishell
minishell> pwd
/home/user/minishell
minishell> cd ..
minishell> echo "Learning is fun" > test.txt
minishell> cat test.txt
Learning is fun
minishell> exit

Architecture

The minishell project is divided into multiple modules, each handling a different aspect of shell functionality:

• Parser: Processes the user's input, breaking it down into commands, arguments, and operators (pipes/redirections).
• Executor: Handles the execution of commands, whether built-in or external.
• Environment Manager: Manages environment variables, supporting creation, updating, and deletion.
• Signal Handler: Ensures that signals like SIGINT and SIGQUIT are properly captured and managed.
• Utilities: Helper functions for string manipulation, memory management, and system interactions.

Limitations

While minishell successfully implements many core shell features, there are a few limitations:

• No job control (background processes with & are not supported).
• Limited error messages for certain edge cases.
• Doesn't support advanced scripting features like loops or conditionals.