How to feed information to a Python daemon?

Question

I have a Python daemon running on a Linux system. I would like to feed information such as "Bob", "Alice", etc. and have the daemon print "Hello Bob." and "Hello Alice" to a file.

This has to be asynchronous. The Python daemon has to wait for information and print it whenever it receives something.

What would be the best way to achieve this?

I was thinking about a named pipe or the Queue library but there could be better solutions.

Answer 1

Here is how you can do it with a fifo:

# receiver.py

import os
import sys
import atexit

# Set up the FIFO
thefifo = 'comms.fifo'
os.mkfifo(thefifo)

# Make sure to clean up after ourselves
def cleanup():
    os.remove(thefifo)
atexit.register(cleanup)

# Go into reading loop
while True:
    with open(thefifo, 'r') as fifo:
        for line in fifo:
            print "Hello", line.strip()

You can use it like this from a shell session

$ python receiver.py &
$ echo "Alice" >> comms.fifo
Hello Alice
$ echo "Bob" >> comms.fifo
Hello Bob