A Zsh-like Shell written in C#

This repository implements a custom shell in C# inspired by zsh, adhering to clean coding practices. The shell includes essential functionalities like command execution, navigation, quoting, and redirection.

Features

Core Functionalities

• Print a prompt: Displays a customizable shell prompt to the user.
• Handle invalid commands: Gracefully handles unrecognized commands with appropriate error messages.
• REPL (Read-Eval-Print Loop): Implements an interactive loop for continuous command execution.
• The exit builtin: Allows the user to exit the shell.

Built-in Commands

echo

• Repeats the arguments provided.
• Supports quoting for spaces and special characters.

type

• Builtins: Identifies and displays shell built-in commands.
• Executable files: Checks and displays information about executable files in the user's PATH.

Running External Programs

• Executes programs and handles errors for missing or inaccessible executables.

Navigation

pwd

• Prints the current working directory.

cd

• Absolute paths: Navigates to directories using absolute paths.
• Relative paths: Navigates using paths relative to the current directory.
• Home directory: Navigates to the user's home directory.

Quoting

• Single quotes: Preserves the literal value of all characters within the quotes.
• Double quotes: Allows interpolation of variables and special characters.
• Backslash outside quotes: Escapes the next character.
• Backslash within quotes:
  • Within single quotes: Treated literally.
  • Within double quotes: Escapes special characters like " and $.

Executing a Quoted Executable

• Handles execution of commands where the executable name is quoted.

Redirection

• Redirect stdout: Supports > to redirect standard output to a file.
• Redirect stderr: Supports 2> to redirect standard error to a file.
• Append stdout: Supports >> to append standard output to a file.
• Append stderr: Supports 2>> to append standard error to a file.

Code Structure

The shell is designed following clean coding principles:

• Modular Architecture: Makes use of the Command Architecture Pattern
• Error Handling: Gracefully handles edge cases, providing meaningful error messages.

Installation

1. Clone this repository:

   git clone https://github.com/your-username/custom-shell-csharp.git
   cd custom-shell-csharp

2. Build the project using .NET:

   dotnet build

3. Run the shell:

   dotnet run

4. Alternatively, if you have installed .NET using HomeBrew, use the provided shell.sh script for easier execution.

   ./shell.sh
   

Usage

Once the shell is running, you can use the following commands:

• pwd: Prints the current directory.
• cd [directory]: Navigates to the specified directory.
• echo [arguments]: Prints the arguments.
• type [command]: Displays information about the command.
• Redirect output or error streams with >, 2>, >>, 2>>.

Examples

Navigation

> pwd
/home/user
> cd /tmp
> pwd
/tmp

Quoting

> echo "Hello, World!"
Hello, World!
> echo 'Single quoted: \n'
Single quoted: \n
> echo "Backslash: \n"
Backslash:

Redirection

> echo "Hello" > file.txt
> cat file.txt
Hello
> echo "Append this" >> file.txt
> cat file.txt
Hello
Append this