POSIX Shell

This project is a custom-built POSIX-compliant shell, written in C. The shell implements essential features such as command parsing, execution of external programs, and handling built-in commands (e.g., cd, pwd, echo). It also supports advanced features, including quoted strings, input/output redirection, and more, simulating a fully functional shell environment.

Features

• POSIX Compliance: Fully adheres to POSIX standards, ensuring compatibility with a wide range of shell commands and external programs.
• Built-in Commands: Implements common shell built-ins, such as:
  • exit: Exits the shell with a custom exit status.
  • pwd: Prints the current working directory.
  • echo: Outputs text or variables to the terminal.
  • cd: Changes the current directory, supporting absolute, relative paths, and home directory navigation.
• Command Parsing: Efficiently parses shell commands and arguments, supporting both built-in commands and external executables.
• Redirection: Supports input/output redirection, allowing you to:
  • Redirect stdout to files.
  • Redirect stderr to files.
  • Append to stdout or stderr.
  • Redirect input from files to programs.
• Quoting: Properly handles quoted strings and escape sequences, including:
  • Single (') and double (") quotes.
  • Backslashes (\) for escaping special characters.
• REPL (Read-Eval-Print Loop): The shell continuously reads input, processes commands, and prints results, creating a smooth, interactive experience for the user.

Installation

Clone the Repository

Start by cloning the repository to your local machine:

git clone https://github.com/yourusername/shell.git
cd shell

Compile the Project

To compile the shell, use gcc(or any other C compiler):

gcc main.c -o shell

Run the Shell

After compiling, you can run the shell by executing the following command:

./shell

Usage

Once the shell is running, you can interact with it by typing commands. It will behave similarly to a standard Unix shell, executing both built-in and external commands.

Example Commands

• pwd - Prints the current working directory.
• echo Hello, World! - Outputs Hello, World! to the terminal.
• cd /path/to/directory - Changes the current directory to the specified path.
• ls > output.txt - Redirects the output of the ls command to a file named output.txt.
• ls 2> error.txt - Redirects the error output of the ls command to a file named error.txt.
• cat < input.txt - Redirects the contents of input.txt to the cat command as input.

Contributing

Contributions are welcome! If you have suggestions for improvements, bug fixes, or new features, feel free to fork the repository and submit a pull request.