Custom Shell - A Basic Shell Implementation

This project is a custom shell implemented using Bash and enhanced with Python to demonstrate various operating system-related features. The shell supports command history, environment variable management, command aliases, and the ability to handle chaining, piping, and redirection.

Features

• Command History: Stores and displays previously executed commands.
• Environment Variables: Set and display environment variables.
• Aliases: Create, list, and remove aliases for commands.
• Command Chaining (&&): Execute multiple commands sequentially, stopping if one fails.
• Piping (|): Redirect the output of one command as input to another.
• Redirection (>, >>): Redirect command output to files.
• Background Jobs (&): Execute commands in the background.
• Directory Navigation (cd): Change the current working directory.
• Website Opening: Open a URL in the default browser with open <URL>.
• Help: Provides a list of available commands.

Installation

To use this custom shell, you must have Bash and Python installed. Ensure that you have access to xdg-open for opening URLs.

1. Clone the repository:

   git clone https://github.com/yourusername/custom-shell.git

2. Navigate to the project directory:

   cd custom-shell

3. Run the shell:

   ./myshell.sh

Usage

Once the shell starts, you can use the following commands:

• history - Display the command history.
• env - Show the current environment variables.
• set VAR VALUE - Set an environment variable.
• alias name command - Create a command alias.
• alias -l - List all aliases.
• unalias name - Remove an alias.
• cd <directory> - Change the directory.
• open <URL> - Open a website in the browser.
• help - Display this help message.
• exit - Exit the shell.

Command Chaining

You can chain commands together using &&:

$ ls && echo "Directory listed"

Command Piping

You can pipe the output of one command into another using |:

$ ls | grep "file"

Redirection

Redirect the output of a command to a file using > for overwriting or >> for appending:

$ echo "Hello, World" > output.txt
$ echo "Appended text" >> output.txt

Background Jobs

You can run commands in the background using &:

$ long_running_command &

Aliases

You can create command aliases to shorten repetitive commands:

$ alias ll="ls -l"
$ ll  # Executes ls -l

To remove an alias:

$ unalias ll

Acknowledgments

• This project was created as part of an Operating Systems course.
• Thanks to the community for open-source contributions and tutorials that helped guide the development of this shell.