A Unix socket (also called a Unix domain socket or IPC socket) is a special file used for inter-process communication (IPC) on Unix-like operating systems. It enables two processes running on the same machine to communicate efficiently without using network protocols like TCP/IP.

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🔹 Key Concepts of Unix Sockets #

1. File-Based Communication:
   • Unlike TCP/IP sockets, Unix sockets exist as special files in the filesystem (e.g., /tmp/mysocket).
   • Processes read and write data to these files to exchange information.
2. Faster than TCP/IP Sockets:
   • Since Unix sockets don’t use network layers, they offer lower latency and higher efficiency compared to network sockets.
3. Two Main Types:
   • Stream Sockets (SOCK_STREAM): Provides reliable, connection-based communication (like TCP).
   • Datagram Sockets (SOCK_DGRAM): Provides connectionless, unordered communication (like UDP).
4. Permissions & Security:
   • Since Unix sockets are represented as files, they inherit Unix file permissions, allowing fine-grained access control.

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🔹 How Unix Sockets Work #

1. Creating a Socket: A server process creates a socket file in the filesystem.
2. Binding & Listening: The server binds to the socket file and listens for incoming connections.
3. Connecting: A client process connects to the socket file.
4. Data Exchange: The server and client send and receive data.
5. Closing the Connection: The socket is closed when communication is done.

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🔹 Example: Creating and Using a Unix Socket in Python #

import socket
import os

# Define socket file path
SOCKET_PATH = "/tmp/mysocket"

# Remove existing socket file if it exists
if os.path.exists(SOCKET_PATH):
    os.remove(SOCKET_PATH)

# Create a Unix socket
server_socket = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
server_socket.bind(SOCKET_PATH)
server_socket.listen(1)

print("Server is waiting for a connection...")
conn, _ = server_socket.accept()

# Receive and respond to messages
data = conn.recv(1024)
print("Received:", data.decode())
conn.sendall(b"Hello from server!")

# Cleanup
conn.close()
server_socket.close()
os.remove(SOCKET_PATH)

👉 This is a simple server that listens on a Unix socket, receives a message, and replies.

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🔹 When to Use Unix Sockets #

✅ When two processes on the same machine need to communicate efficiently
✅ For faster IPC than TCP/IP sockets
✅ To take advantage of file-based access control

🚫 Not suitable for communication between different machines—use TCP/IP sockets instead.

Let me know if you want a more detailed example! 🚀