Java Shell Implementation

A lightweight shell implementation in Java that supports basic Unix-like commands. This shell provides a minimal command-line interface with support for common shell operations.

Features

• Basic command prompt interface ($)

• Built-in commands:

  • pwd - Print working directory
  • cd - Change directory (supports absolute paths and ~ for home directory)
  • echo - Print text to console (supports both quoted and unquoted strings)
  • type - Display information about command type
  • exit - Exit the shell

• External command execution through PATH lookup

• Path normalization and validation

• Home directory resolution (~)

Requirements

• Java 11 or higher
• java.nio.file support
• Operating system with PATH environment variable

Installation

1. Clone this repository:

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

2. Compile the Java file:

javac Main.java

3. Run the shell:

java Main

Usage

The shell provides a command prompt ($) where you can enter commands:

$ pwd
/current/working/directory
$ echo "Hello World"
Hello World
$ cd ~
$ type echo
echo is a shell builtin

Supported Commands

1. pwd

   • Displays the current working directory

2. cd [directory]

   • Changes the current working directory
   • Supports absolute paths and ~ for home directory
   • Example: cd ~/Documents or cd /usr/local

3. echo [text]

   • Prints text to the console
   • Supports both quoted and unquoted strings
   • Example: echo Hello World or echo "Hello World"

4. type [command]

   • Displays whether a command is a shell builtin or its location in PATH
   • Example: type pwd or type java

5. exit 0

   • Exits the shell

Implementation Details

• Uses Java NIO for file operations
• Implements PATH lookup for external commands
• Handles both built-in commands and external executables
• Supports basic string parsing for command arguments
• Implements working directory management

Limitations

• Basic command parsing (no advanced shell features)
• Limited support for command arguments and flags
• No pipeline support
• No environment variable expansion
• No wildcard support
• No command history

Contributing

Feel free to submit issues and enhancement requests!