MiniShell

Project Overview

MiniShell is a simple Unix-like command-line shell implemented in C as a learning exercise. This project demonstrates how to:

• Launch external commands using the exec family of functions
• Implement pipelines (|) to connect processes
• Perform standard input/output redirections (<, >, >>)
• Handle environment variables
• Recognize and execute built-in commands (e.g., cd, echo, export, unset, pwd, env, exit)
• Manage child processes and handle signals
• Support heredoc (<<) syntax

Key components include a lexer, parser, executor, signal handler, and integration with GNU Readline for interactive input.

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Features

1. Command Parsing

   • Tokenization of input, respecting single and double quotes
   • Environment variable expansion (e.g., $VAR)
   • Heredoc support (<<)

2. Command Execution

   • Running external programs and scripts
   • Handling multiple pipelines
   • Redirecting input and output to files

3. Built-in Commands

   • cd — Change directory
   • echo — Display a line of text
   • pwd — Print working directory
   • export — Set environment variables
   • unset — Unset environment variables
   • env — List environment variables
   • exit — Exit the shell

4. Signal Handling

   • Custom handling for SIGINT (Ctrl+C) and SIGQUIT (Ctrl+)

5. Dependencies

   • GNU Readline (v8.2) for command-line editing
   • Custom libft library (constructed as part of the 42 curriculum)

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Repository Structure

minishell/
├── srcs/
│   ├── lexer/            # Tokenizes input strings
│   ├── parser/           # Builds command trees from tokens
│   ├── exec/             # Executes commands and pipelines
│   ├── builtins/         # Implementation of built-in commands
│   ├── libft/            # Custom C utility library
│   └── redirections.c    # Functions for I/O redirection
├── readline/             # Automatically downloaded and built GNU Readline sources
├── Makefile              # Build targets and dependency rules
├── leaks.sh              # Script to check for memory leaks
└── README.md             # Project documentation

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Installation

1. Clone the repository:

   git clone https://github.com/faruktinaz/minishell.git
   cd minishell

2. Build the project using the provided Makefile:

   make

   This command will download and compile the Readline library and build the minishell executable using the libft utility library.

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Usage

Start the shell by running:

./minishell

Within the shell, you can:

• Execute standard Unix commands (e.g., ls, grep, cat)
• Use pipelines and redirections
• Test built-in commands like cd, export, and exit

To monitor memory leaks while the shell is running, execute in another terminal:

./leaks.sh

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Testing & Debugging

• The leaks.sh script periodically checks running minishell processes for memory leaks.
• Compiler flags -Wall -Wextra -Werror are enabled to catch warnings and treat them as errors.

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