How to: Linux Check Processes

Managing processes is an essential task for any Linux system administrator. There are times when you need to check the running processes on your system, such as when troubleshooting an issue or monitoring system performance. In this article, we will discuss the various methods to check processes in Linux and provide code examples to illustrate their usage.

What is a Process?

A process is a running instance of a program on a Linux system. Every process has a unique process ID (PID) assigned by the Linux kernel. The PID helps to identify and manage the running processes on the system. Each process has its own memory space, CPU time, and other system resources.

Checking Processes in Linux

There are several ways to check processes in Linux. Here are some of the most commonly used methods:

1. ps Command

The ps command is used to display information about the running processes on a Linux system. The command provides a snapshot of the current system state in a tabular format. You can use various options with the ps command to display detailed information about the processes, such as PID, CPU usage, memory usage, and more.

Here is an example of how to use the ps command to display the running processes on a Linux system:

ps aux

The ps aux command displays all the running processes on the system, including the processes started by other users. The output includes the PID, user, CPU usage, memory usage, and other details.

2. top Command

The top command is a popular utility to monitor system processes in real-time. It provides an interactive interface to display the running processes and their resource usage. The top command updates the information every few seconds, allowing you to monitor the system performance continuously.

Here is an example of how to use the top command to display the running processes on a Linux system:

top

The top command displays the running processes in real-time and updates the information every few seconds. The output includes the PID, user, CPU usage, memory usage, and other details.

3. htop Command

The htop command is an advanced version of the top command that provides a more user-friendly and interactive interface to monitor system processes. It provides a color-coded display to highlight the resource usage of the running processes. The htop command also allows you to sort the processes based on various criteria, such as CPU usage, memory usage, and more.

Here is an example of how to use the htop command to display the running processes on a Linux system:

htop

The htop command displays the running processes in an interactive and user-friendly interface. The output includes the PID, user, CPU usage, memory usage, and other details.

4. System Monitor

System Monitor is a graphical utility that provides a user-friendly interface to monitor system processes. It displays the running processes and their resource usage in a graphical format. You can use System Monitor to kill or terminate a process, set process priorities, and more.

To launch System Monitor, go to the Applications menu, select System Tools and click on System Monitor.

5. Kill Command

The kill command is used to terminate a running process on a Linux system. You need to specify the PID of the process you want to terminate with the kill command. The kill command sends a signal to the process to terminate it gracefully.

Here is an example of how to use the kill command to terminate a process on a Linux system:

kill PID

Replace PID with the actual process ID of the process you want to terminate.

Conclusion

In this article, we discussed the various methods to check processes in Linux. The ps command provides a snapshot of the system processes, while the top and htop commands provide real-time monitoring of the system processes. System Monitor is a graphical utility that provides a user-friendly interface to monitor system processes. The kill command is used to terminate a running process on a Linux system.

As a Linux system administrator, you should be familiar with these methods to check and manage the running processes on your system. These tools help you to troubleshoot issues, monitor system performance, and optimize resource usage.