Learn how to check a process by PID with Python.

Are you tired of constantly checking your computer’s task manager to monitor the processes running in the background? Do you want to know how to automate the process of checking a specific program’s PID with Python? If you answered yes, then this article is for you.

In this tutorial, we will teach you how to check a process by PID with Python. We will provide you with step-by-step instructions on how to use the psutil library to find the PID of a specific process and perform various actions based on the results. Whether you are a beginner or an experienced programmer, our guide will help you understand how to identify and monitor processes running in your system.

You will learn how to identify which processes are consuming the most resources and affecting the performance of your system. We will also show you how to use Python to kill a process by its PID, saving you time and effort in managing your tasks. By the end of this tutorial, you will have the necessary skills to manage and monitor processes efficiently, automating routine tasks and freeing up valuable time for yourself.

The ability to automate processes like checking for PIDs with Python can save you time, increase productivity, and make your day-to-day life easier. With our comprehensive tutorial, even those with minimal programming experience can gain a wealth of knowledge and skill. So why wait? Start learning how to check a process by PID with Python today!

“How To Check If There Exists A Process With A Given Pid In Python?” ~ bbaz

Introduction

Checking a process through its Process ID or PID is a critical part of systems administration. The PID is the unique identifier that every running program gets when it starts. Monitoring these IDs is essential to troubleshoot performance issues or kill non-responsive processes. One way to achieve this is by using Python. In this comparison article, we will go through different methods of checking a process using a PID with Python and compare their strengths and weaknesses.

Method 1: os.kill(pid, 0)

Overview

One way to check if a process is running or not is to use the os.kill method with a signal value of 0. Signal 0 is a unique signal that does not do anything when sent to a process; it only checks if the process is running. If the process is running, then it returns None; otherwise, it raises an exception.

Pros

• The os.kill() method is efficient and simple to use.
• It can be used to check if the process is running without knowing its name.

Cons

• The method raises an exception if the process is not running, which could cause issues if used extensively.
• It requires root privileges to use in Linux due to security reasons.

Method 2: psutil.pid_exists(pid)

Overview

psutil is a cross-platform library for retrieving information on running processes and system utilization, including CPU, memory, disks, network, sensors, and more. It provides lots of functionalities that allow us to monitor running processes. One of its methods is pid_exists(), which returns Boolean True if the process is still running, and False otherwise.

Pros

• The pid_exists() method is efficient, as it does not raise any exception and returns True or False based on the pid’s state.
• It provides much more functionality than merely checking if a process is running, such as retrieving CPU usage, memory usage, disk usage, and more.

Cons

• psutil requires additional installation and cannot be used out-of-the-box.
• It has limited support for some platforms, such as Solaris and AIX.

Method 3: subprocess.call([‘ps’, ‘-p’, str(pid)])

Overview

The subprocess.call() method can be used to execute shell commands from within a Python script. By using the ps command with the -p option and passing it the PID, we can obtain the status of the process. The exit code reveals whether the process is running.

Pros

• The subprocess.call() method is easy to use and requires minimal programming knowledge.
• It is cross-platform and does not require any additional installations.

Cons

• This method involves creating a subprocess, which could slow down the program.
• It relies on shell commands, which may vary depending on the operating system.

Method 4: /proc Filesystem

Overview

On Linux systems, the /proc filesystem is a virtual filesystem that provides an interface to kernel data structures. All running processes are represented as directories in the /proc directory. Each process has a unique directory named after its process ID. By checking if the corresponding process directory exists or not, we can determine if the process is still running or not.

Pros

• The /proc filesystem method is the fastest and most efficient way to check if a process is running.
• It does not require any external modules to be installed.

Cons

• It only works on Linux-based systems.
• Reading files from the /proc directory requires root privileges.

Conclusion

Each method described above has its strengths and weaknesses. However, depending on the use case, one method may be more useful than the others. For example, if the program only needs to check the status of one or two processes, it might be easier and faster to use Method 1 or 4. On the other hand, if the program needs to monitor multiple processes and gather more information about each one, then Method 2 and 3 might provide a better solution.

Method	Pros	Cons
os.kill(pid, 0)	Efficient and simple to use. Can be used to check if the process is running without knowing its name.	Raises an exception if the process is not running. Requires root privileges to use in Linux.
psutil.pid_exists(pid)	Efficient as it does not raise any exception and returns True or False based on the pid’s state. Provides much more functionality than merely checking if a process is running, such as retrieving CPU usage, memory usage, disk usage, and more.	Requires additional installation and cannot be used out-of-the-box. Has limited support for some platforms, such as Solaris and AIX.
subprocess.call([‘ps’, ‘-p’, str(pid)])	Easy to use and requires minimal programming knowledge. Cross-platform and does not require any additional installations.	Involves creating a subprocess which could slow down the program. Relies on shell commands which may vary depending on the operating system.
/proc Filesystem	Fastest and most efficient way to check if a process is running. Does not require any external modules to be installed.	Only works on Linux-based systems. Reading files from the /proc directory requires root privileges.

When it comes to checking a process by PID with Python, there are a few common questions that people ask. Below are some of the most frequently asked questions and their answers:

• What is a PID?

A PID (Process Identifier) is a number that identifies a running process on a computer system. Each process on a system is assigned a unique PID by the operating system.

• How do I get the PID of a process?

You can use the os.getpid() function in Python to get the PID of the current process. To get the PID of another process, you can use the psutil module.

• How can I check if a process is running by PID?

You can use the psutil module to check if a process is running by PID. The psutil.process_exists(pid) function returns True if the process with the given PID is running, or False if it is not.

• How can I kill a process by PID?

You can use the os.kill(pid, signal.SIGTERM) function to send a termination signal to a process with the given PID. This will cause the process to gracefully exit. If the process does not exit after a certain amount of time, you can use the os.kill(pid, signal.SIGKILL) function to forcefully terminate the process.

• Can I check the status of a process by PID?

Yes, you can use the psutil module to check the status of a process by PID. The psutil.Process(pid).status() function returns the current status of the process with the given PID (e.g. running, stopped, zombie, etc.).