🐚 minishell

As beautiful as a shell.

Installation & Usage

🛠️ Prerequisites

The following environment and tools are required for the build:

• Compiler: gcc (v11+) or clang
• Build System: GNU Make (v3.81+)
• Standard: C99 compliant

# Clone
git clone --recursive https://github.com/shonakam/minishell.git

# Compile
cd minishell
make

# Execution
./minishell

Core Architectures

This project is a micro-architecture-oriented UNIX shell, rebuilding POSIX-compliant process management from scratch. It is not merely a command executor, but a system focused on AST (Abstract Syntax Tree) based logical execution and job control.

0. Input Engine: Custom Readline (srcs/readline)

To achieve a zero-dependency architecture, the line-editing system was implemented from scratch using low-level terminal control.

• Terminal Control: Direct manipulation of termios to switch between canonical and raw modes.

• Buffer Management: Real-time handling of input strings with support for dynamic cursor positioning and multi-line rendering.

• ANSI Escape Sequences: Custom parser for handling terminal-specific codes for arrow keys, Ctrl shortcuts, and screen clearing.

• History Interface: An integrated history management system allowing seamless navigation of previous commands.

1. Session Management (srcs/session)

Manages the unique, persistent state (Context) shared across the entire process.

• Environment: Maintenance and serialization of the environment variable list.

• Status: Management of the most recent exit status ($?).

• Signal Control: Dynamic switching of signal behavior between interactive mode and execution mode.

2. Analysis Engine (srcs/lexer, srcs/parser)

Decomposes strings into meaningful units (tokens) and constructs an AST using recursive descent parsing.

• FSM Lexer: Accurate lexical analysis utilizing a Finite State Machine.

• Syntax Validator: Verifies grammatical consistency for &&, ||, |, and parentheses prior to execution.

3. Expansion System (srcs/executor/expander)

Transforms strings within the AST into an executable form immediately before execution. Variable Expansion: Replacement of $VAR with environment variable values.

• Quote Removal: Removal of single (') and double (") quotes.

• Wildcard (*): Pattern matching and expansion for filenames in the current directory.

  • Note: Supports single-level depth only; specialized for matching patterns that do not contain /.

• Heredoc: Pre-execution preparation of all heredocs and temporary file management.

4. Execution Engine (srcs/executor)

Recursively traverses the AST to perform process generation and I/O control.

• Logical Ops: Controls conditional execution via && and ||.

• Pipeline: Connects multiple processes using pipe() and fork().

• Subshell Isolation: Ensures complete separation of execution contexts via (...). By recursively calling the exec_engine within child processes, it supports infinite nesting of scopes.

• Job Control: Full synchronization of background execution (&) and comprehensive cleanup upon termination.

End of Session

May your exit status always be 0. Happy Hacking! 🐚✨