Simple Network Shell (SNS)

An interactive shell that runs in both client and server modes over UNIX or TCP sockets. Supports standard shell-like command execution with features such as piping, I/O redirection, script execution, and internal management commands.

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📖 Author

Aliaksei Zimnitski
2nd Year, 4th Semester – Informatika
Date: 01.04.2025

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🧠 Features

• Dual operation mode: server and client
• Socket support:
  • UNIX domain sockets (local IPC)
  • TCP/IP sockets (remote connections)
• Command features:
  • Chaining using ;
  • Piping using |
  • Input/output redirection with <, >, >>
• Built-in internal commands:
  • help — display internal command help
  • halt — stop the server and disconnect all clients
  • quit — disconnect a single client
  • stat — list all active connections
  • abort <id> — forcibly disconnect a specific client
• Script execution support from file (non-interactive)
• Cross-platform: Works on Linux and FreeBSD
• Modular code structure with separated libraries (e.g. redirection)
• Descriptive English documentation

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🚀 Usage

🛠 Compile

gcc -o shell main.c server.c client.c redirections.c

🟢 Run as Server (default)

./shell -s                       # Default mode
./shell -s -u /tmp/myshell.sock # UNIX socket
./shell -s -p 1234 -i 127.0.0.1 # TCP socket

🔵 Run as Client

./shell -c -u /tmp/myshell.sock           # Connect to UNIX socket
./shell -c -p 1234 -i 127.0.0.1           # Connect to TCP socket
./shell -c "ls -la | grep txt"            # One-shot command

📜 Run Script (Server Only)

./shell script.txt

❓ Help

./shell -h

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🧩 Optional Features Implemented

ID	Feature	Points
1	Non-interactive mode (script file execution)	2
2	Cross-platform support (Linux, FreeBSD)	2
3	Internal command stat for active connections	3
4	Internal command abort <id> to terminate specific connections	2
7	IP address flag -i for TCP sockets	2
11	Use of external library for redirection handling	2
15	Internal commands work as flags with -c (e.g., -halt, -help)	2
23	Extensive English documentation and inline comments	1
	Total	16

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📚 Internal Commands

• help – Show internal help message
• cd – Change working directory
• halt – Stop the server and all clients
• quit – Disconnect current client
• stat – Show all active client connections
• abort – Disconnect a specific client by ID

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🔧 Future Enhancements

• Prompt customization and formatting via internal prompt command
• Idle timeout with -t flag or environment variable
• Logging support (-l logfile.txt)
• Daemon mode support (-d)
• Wildcard/globbing (*) in command arguments
• Load config from file with -C config.cfg

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