NovaShell

A lightweight, feature-rich command shell written in C. NovaShell provides a modern terminal experience with built-in commands, environment variable management, script execution, and more.

Features

• Built-in Commands: Essential shell commands including cd, pwd, echo, export, clear, and help
• Environment Variable Management: Full support for setting, exporting, and expanding environment variables
• Script Execution: Execute shell scripts (.sh files) and any executable with shebang
• Command History: Persistent command history with up/down arrow navigation
• Tab Completion: Auto-completion for built-in commands
• Colorful Interface: Beautiful color-coded output with customizable themes
• Cross-Platform: Built on standard C libraries for wide compatibility

Installation

Prerequisites

• GCC compiler
• Standard C libraries (unistd.h, stdlib.h, etc.)
• Make (optional, for building)

Building from Source

1. Clone or download the NovaShell source code
2. Navigate to the project directory
3. Compile the shell:

make compile

Or manually:

gcc -Wall -Wextra src/main.c src/utils.c src/linenoise.c -o nsh -Isrc/libs

4. Run NovaShell:

./nsh

Usage

Basic Usage

Start NovaShell by running the compiled binary:

./nsh

You'll see the NovaShell prompt:

nsh — Nova Shell
nsh v1.0.0
Type `help` to show available commands!

nsh $ 

Built-in Commands

exit

Exit the shell.

nsh $ exit

pwd

Print the current working directory.

nsh $ pwd
/home/user/projects

cd [directory]

Change the current directory.

nsh $ cd /path/to/directory
nsh $ cd ..          # Go up one directory
nsh $ cd             # Go to home directory

echo [text]

Print text to the terminal with variable expansion support.

nsh $ echo "Hello, World!"
Hello, World!

nsh $ echo "Current user: $USER"
Current user: username

nsh $ echo "Home directory: ${HOME}"
Home directory: /home/username

export [VAR[=value]]

Manage environment variables.

# Set a new variable
nsh $ export MY_VAR=hello

# Export an existing variable
nsh $ export PATH

# List all environment variables
nsh $ export
declare -x HOME=/home/user
declare -x PATH=/usr/bin:/bin
declare -x MY_VAR=hello

clear

Clear the terminal screen.

nsh $ clear

help

Show help information for all built-in commands.

nsh $ help
  exit                    Exit the shell
  pwd                     Print current working directory
  cd <directory>          Change directory
  export                  List all environment variables
  export VAR=value        Set and export environment variable
  export VAR              Export existing variable
  echo [text]             Print text (supports $VAR expansion)
  clear                   Clear the screen
  help                    Show this help message

Script Execution

NovaShell can execute shell scripts in two ways:

1. Direct Script Execution

Run a script file directly:

nsh $ ./myscript.sh
nsh $ ./myscript.sh arg1 arg2

2. Command Line Script Execution

Execute a script as the first argument to NovaShell:

nsh $ ./nsh myscript.sh
nsh $ ./nsh myscript.sh arg1 arg2

Environment Variables

NovaShell supports full environment variable management:

Setting Variables

nsh $ export MY_VAR=value
nsh $ export PATH=/usr/local/bin:$PATH

Variable Expansion in Echo

nsh $ echo "User: $USER, Home: $HOME"
User: username, Home: /home/username

nsh $ echo "Full path: ${HOME}/Documents"
Full path: /home/username/Documents

Command History

NovaShell maintains a persistent command history:

• Use up/down arrow keys to navigate through previous commands
• History is saved to history.txt in the current directory
• History is loaded automatically when NovaShell starts

Tab Completion

NovaShell provides tab completion for built-in commands:

• Type the beginning of a command and press Tab
• Available completions will be shown
• Works for all built-in commands: exit, cd, echo, export, clear, help, pwd

Color Scheme

NovaShell uses a carefully designed color scheme:

• Prompt/Commands: Bright cyan (#64C8FF)
• Regular Output: Light gray/white (#E6E6E6)
• Success Messages: Bright green (#64FF64)
• Warnings: Bright yellow/orange (#FFC864)
• Errors: Bright red (#FF6464)
• Info Text: Soft blue (#96C8FF)

Project Structure

NovaShell/
├── src/
│   ├── main.c              # Main shell implementation
│   ├── utils.c             # Utility functions and command handlers
│   ├── linenoise.c         # Line editing library
│   └── libs/
│       ├── utils.h         # Header file with function declarations
│       └── linenoise.h     # Line editing library header
├── Makefile               # Build configuration
├── README.md              # This documentation file
├── LICENSE                # GNU GPLv3 license
└── THIRD_PARTY_LICENSES.txt  # Third-party license information

Development

Building

make compile    # Compile the shell
make clean      # Remove compiled binary
make run        # Compile and run

Adding New Commands

To add new built-in commands:

1. Add the command name to the commands array in completion() function in utils.c
2. Add command handling logic in the main loop in main.c
3. Update the help text in the help command

Contributing

Contributions are welcome! Please follow these guidelines:

• Maintain the existing code style
• Add appropriate error handling
• Update documentation for new features
• Test thoroughly before submitting

License

NovaShell is my own code and is licensed under the GNU GPLv3 (see LICENSE).

NovaShell uses the following third-party libraries:

• linenoise (BSD 2-Clause License)
  Full license text included in THIRD_PARTY_LICENSES.txt

If you redistribute NovaShell or its binaries, please preserve all copyright notices and license texts for third-party libraries.