Of course! Using Python with the paramiko library to "tail" a remote file is a common and powerful task. It's perfect for real-time log monitoring.

Here’s a complete guide, starting with the basic concept and moving to a robust, production-ready solution.

Core Concept: How to "Tail" with Paramiko

You can't use a single command like tail -f directly with Paramiko. Instead, you simulate it by:

1. Connecting to the remote server via SSH.
2. Executing a command that reads the file's contents up to a certain point.
3. Storing the current file size.
4. Looping:
   • Wait for a short interval.
   • Check the file's new size.
   • If the size has increased, execute the command again to read only the new bytes.
   • Print the new bytes to your console.

Method 1: The Simple, Blocking Example

This example is great for understanding the basic logic. It will run indefinitely and block your script.

import paramiko
import time
# --- Configuration ---
HOSTNAME = "your_server_ip"
USERNAME = "your_username"
KEY_FILENAME = "/path/to/your/private_key" # Or use password
PORT = 22
REMOTE_FILE_PATH = "/var/log/syslog" # The file you want to tail
# --- SSH Connection ---
try:
    # Create an SSH client
    client = paramiko.SSHClient()
    # Automatically add the server's host key (for testing/dev only)
    # In production, you should load known hosts.
    client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
    # Connect to the server
    print(f"Connecting to {USERNAME}@{HOSTNAME}...")
    client.connect(hostname=HOSTNAME, username=USERNAME, port=PORT, key_filename=KEY_FILENAME)
    print("Connected successfully.")
    # --- Initial File Size Check ---
    # First, get the initial size of the file
    sftp = client.open_sftp()
    initial_stat = sftp.stat(REMOTE_FILE_PATH)
    initial_size = initial_stat.st_size
    print(f"Initial file size: {initial_size} bytes")
    # --- The Tail Loop ---
    while True:
        try:
            # Get the current file size
            current_stat = sftp.stat(REMOTE_FILE_PATH)
            current_size = current_stat.st_size
            # If the file has grown
            if current_size > initial_size:
                # Read the new content from the last known position
                with sftp.file(REMOTE_FILE_PATH, 'r') as remote_file:
                    remote_file.set_pipelining(True) # Can improve performance for large reads
                    remote_file.seek(initial_size) # Go to the end of where we last read
                    new_data = remote_file.read() # Read the new bytes
                    # Print the new data
                    if new_data:
                        print(new_data.decode('utf-8'), end='')
                # Update the size for the next loop iteration
                initial_size = current_size
            # Wait for a short period before checking again
            time.sleep(1)
        except FileNotFoundError:
            print(f"Error: File {REMOTE_FILE_PATH} not found on the remote server.")
            break
        except Exception as e:
            print(f"An error occurred during tailing: {e}")
            break
except paramiko.AuthenticationException:
    print("Authentication failed, please verify your credentials.")
except paramiko.SSHException as e:
    print(f"Unable to establish SSH connection: {e}")
except Exception as e:
    print(f"An unexpected error occurred: {e}")
finally:
    # Ensure the connection is closed
    if 'client' in locals() and client:
        client.close()
        print("SSH connection closed.")

How to Run It:

1. Install Paramiko: pip install paramiko
2. Fill in your details: Replace your_server_ip, your_username, and /path/to/your/private_key.
3. Run the script: python your_script_name.py

You will see new lines from the log file appear in your console as they are written on the remote server.

Method 2: A Robust, Non-Blocking Class (Recommended)

For real applications, you want a non-blocking solution that can be integrated into a larger application (like a web service or a GUI). The best way to do this in Python is with asyncio.

This class uses asyncio to run the tailing process in the background without blocking your main program.

import asyncio
import paramiko
import logging
# Optional: Set up basic logging
logging.basicConfig(level=logging.INFO, format='%(asctime)s - %(levelname)s - %(message)s')
class AsyncRemoteFileTailer:
    def __init__(self, hostname, username, key_filename, remote_path, port=22, poll_interval=1):
        self.hostname = hostname
        self.username = username
        self.key_filename = key_filename
        self.remote_path = remote_path
        self.port = port
        self.poll_interval = poll_interval
        self.ssh_client = None
        self.sftp_client = None
        self.file_size = 0
        self._stop_event = asyncio.Event()
    async def connect(self):
        """Establishes the SSH and SFTP connection."""
        loop = asyncio.get_running_loop()
        # Run blocking SSH connection in a thread pool executor
        self.ssh_client = await loop.run_in_executor(
            None, self._create_ssh_client
        )
        self.sftp_client = self.ssh_client.open_sftp()
        # Get initial file size
        stat = await loop.run_in_executor(None, self.sftp_client.stat, self.remote_path)
        self.file_size = stat.st_size
        logging.info(f"Connected and tailing {self.remote_path} from size {self.file_size}")
    def _create_ssh_client(self):
        """Helper function for blocking SSH connection."""
        client = paramiko.SSHClient()
        client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
        client.connect(
            hostname=self.hostname,
            username=self.username,
            port=self.port,
            key_filename=self.key_filename,
            timeout=10
        )
        return client
    async def tail(self, callback):
        """
        Tails the remote file and calls the callback with new data.
        :param callback: A function to call with new data (bytes).
        """
        if not self.sftp_client:
            raise ConnectionError("Not connected. Call connect() first.")
        while not self._stop_event.is_set():
            try:
                # Get current file size in a thread pool executor
                loop = asyncio.get_running_loop()
                stat = await loop.run_in_executor(None, self.sftp_client.stat, self.remote_path)
                current_size = stat.st_size
                if current_size > self.file_size:
                    # Read new data in a thread pool executor
                    new_data = await loop.run_in_executor(
                        None, self._read_new_data, self.file_size
                    )
                    if new_data:
                        # Call the callback with the new data
                        await callback(new_data)
                    self.file_size = current_size
                # Wait for the next poll interval or until stop is requested
                await asyncio.sleep(self.poll_interval)
            except FileNotFoundError:
                logging.error(f"File {self.remote_path} not found.")
                await self.stop()
                break
            except Exception as e:
                logging.error(f"Error during tailing: {e}")
                await self.stop()
                break
    def _read_new_data(self, offset):
        """Helper function to read data from a specific offset."""
        with self.sftp_client.file(self.remote_path, 'r') as f:
            f.seek(offset)
            return f.read()
    async def stop(self):
        """Stops the tailing process and closes the connection."""
        self._stop_event.set()
        if self.sftp_client:
            self.sftp_client.close()
        if self.ssh_client:
            self.ssh_client.close()
        logging.info("Connection closed.")
# --- Example Usage ---
async def print_new_data(data: bytes):
    """A simple callback to print new data to the console."""
    # Ensure we print line by line and don't add extra newlines
    print(data.decode('utf-8'), end='')
async def main():
    # --- Configuration ---
    HOSTNAME = "your_server_ip"
    USERNAME = "your_username"
    KEY_FILENAME = "/path/to/your/private_key"
    REMOTE_FILE_PATH = "/var/log/syslog"
    tailer = AsyncRemoteFileTailer(
        hostname=HOSTNAME,
        username=USERNAME,
        key_filename=KEY_FILENAME,
        remote_path=REMOTE_FILE_PATH,
        poll_interval=0.5  # Check every 0.5 seconds
    )
    try:
        await tailer.connect()
        await tailer.tail(callback=print_new_data)
    except KeyboardInterrupt:
        logging.info("Shutdown requested by user.")
    finally:
        await tailer.stop()
if __name__ == "__main__":
    try:
        asyncio.run(main())
    except KeyboardInterrupt:
        pass

Key Differences and Why the Async Version is Better: