Python Pipe

In operating systems, a pipe is used for inter-process communication. It is a way of passing information from one process to another.

The os module provides functionality to interact with the operating system in Python.

Use the os.pipe() Function to Create a Pipe in Python2

The os.pipe() function returns two file descriptors; one for writing data to the pipe and one for reading data written to the pipe. We will create a pipe to pass information between two processes.

import os

r, w = os.pipe()
p_id = os.fork()
if p_id:
    os.close(w)
    r = os.fdopen(r)
    print("Parent process reading data from the pipe")
    data = r.read()
    print("data =", data)
else:
    os.close(r)
    w = os.fdopen(w, "w")
    print("Child writing data to the pipe")
    w.write("data written by the child")
    w.close()

The child process writes some data to the pipe using the w file descriptor, and the parent process reads the data written to the pipe with the r file descriptor.

Output:

Child writing data to the pipe
Parent process reading data from the pipe
data = data written by the child

The pipe only allows one operation at a time. So, while reading data from it, we have to close the w file descriptor, and while writing data, we have to close the r file descriptor with the os.close() method.