Minishell is a simplified but fully functional recreation of the Bash shell. This project involves deep interaction with the Linux Kernel API, managing processes, memory, and file descriptors manually.

It is not just a command runner; it is a full interpreter that parses user input, handles variable expansion, manages a command history, and controls execution flow using pipes and redirections.

My shell implements the following built-ins from scratch, mirroring Bash behavior:

• echo with option -n
• cd with relative or absolute paths
• pwd to print working directory
• export to manage environment variables
• unset to remove environment variables
• env to print current environment
• exit to terminate the shell cleanly

The shell operates in a continuous Read-Eval-Print Loop (REPL):

1. Lexer/Tokenizer: Splits the raw input string into tokens (Words, Operators, Pipes).
2. Parser: Organizes tokens into a structured command table (AST or Linked List).
3. Expander: Replaces $VAR with values from the environment array.
4. Executor:
   • Creates pipes if needed.
   • fork() processes.
   • Redirects Standard I/O using dup2().
   • Executes binary using execve().

// Simplified Execution Logic
if (fork() == 0) {
    dup2(fd[1], STDOUT_FILENO); // Connect Pipe
    close(fd[0]);
    execve(cmd, args, env);     // Replace process
} else {
    waitpid(-1, &status, 0);    // Parent waits
}

🚀 Installation & Usage Prerequisites GCC Compiler

GNU Readline Library

Building

git clone https://github.com/70rn4d0/MiniShell.git
cd MiniShell_tty
make

Running

./minishell

Example Usage

minishell$ ls -l | grep ".c" | wc -l
minishell$ export 1337="Best School"
minishell$ echo $1337
Best School