Python os.getpid() Method

1. Syntax of Python os.getpid() Method
2. Example 1: Use os.getpid() to Get Process ID of Any Process
3. Example 2: Use os.getpid() to Get Process ID of Parent and Child Process

The getpid() belongs to the os module in the Python programming language. The os module is an in-built library available in Python that offers various functions to communicate with the operating system.

The getpid() method returns the process ID of the current process.

Syntax of Python os.getpid() Method

os.getpid()

Parameters

This method doesn’t accept any parameters.

Return

The getpid() method returns the process ID of the currently running process. The process ID is an integer value and a unique identifier assigned to every process running in the system so that the operating system can manage and identify them without hassle.

Example 1: Use os.getpid() to Get Process ID of Any Process

import os

pid = os.getpid()
print(pid)

Output:

735

The process ID can be any integer value; hence, the output varies from machine to machine.

Example 2: Use os.getpid() to Get Process ID of Parent and Child Process

The os module offers a fork() method that allows us to create a child process. It returns the process ID of the child process; a negative value means failure at creation.

The process that executes this method is known as the parent process.

import os

pid = os.fork()

if pid > 0:
    print("Parent Process ID:", os.getpid())
    print("Child Process ID:", pid)
elif pid == 0:
    print("Parent Process ID:", os.getppid())
    print("Child Process ID:", os.getpid())
else:
    print("Can't create a child process :(")

Output:

Parent Process ID: 3672
Child Process ID: 3673
Parent Process ID: 3672
Child Process ID: 3673

The Python code above first creates a child process and stores the process ID in pid. A child process was successfully executed if the process ID is a non-zero positive value.

Since the same instructions are being executed by two processes concurrently, parent and child, we use if else blocks to separate instructions for each process. Code under if pid > 0: is meant for the parent process (parent code) and code under elif pid == 0: is meant for the child process (child code).

In the parent code, we use the os.getpid() method to get the process ID of the parent process. On the flip side, in the child code, we use the os.getpid() method to get the process ID of the child process and the os.getppid() method to get the process ID of the parent process.

The output verifies that the process IDs retrieved are correct.