The Minishell project is a fundamental part of the 42 curriculum designed to deepen your understanding of Unix system programming and shell implementation. This project involves creating a simple, yet functional, Unix shell that can execute commands, handle pipelines, and manage environment variables. It’s an excellent exercise for developing a strong grasp of process management, memory allocation, and user input handling.
- Command Execution: Supports execution of binaries from the system PATH.
- Built-in Commands: Implements basic built-in commands like cd, echo, pwd, export, unset, and exit.
- Pipelines: Allows the use of pipelines (e.g., ls | grep minishell) for chaining commands.
- Redirections: Handles input (<), output (>), and append (>>) redirections.
- Signal Handling: Manages Unix signals (e.g., SIGINT, SIGQUIT) to handle interrupts gracefully.
- Environment Variables: Supports setting, unsetting, and using environment variables within commands.
- Error Handling: Provides robust error detection and reporting for invalid commands, redirections, and system calls.
The shell uses fork() to create new processes and execve() to execute commands. It also employs waitpid() to handle child process termination, ensuring proper synchronization between the parent and child processes.
Commands are parsed using a lexer and parser approach to handle complex input cases, including quotes, escape characters, and nested commands. Tokenization breaks down the input string into manageable components for execution.
Dynamic memory allocation is extensively used for handling user input, environment variables, and command execution. Proper memory management practices are employed to avoid leaks and ensure efficient resource utilization.
The shell uses file descriptors to manage input and output redirections. For pipelines, the pipe() system call creates communication channels between processes, allowing the output of one command to serve as the input to another.
Custom signal handlers are implemented to manage signals like SIGINT (Ctrl+C) and SIGQUIT (Ctrl+). These handlers ensure the shell can respond to user interrupts without crashing.
To build and run the Minishell project, follow these steps:
- Clone the repository:
- Compile the project:
- Run the shell:
