How to List All Running Processes on the Terminal in Ubuntu

This is an article about how to list all running processes in Ubuntu, a popular Linux distribution widely used for its stability and extensive support. In this article you will find information about various commands that can help you monitor system activity and manage your applications efficiently.

Managing processes effectively is crucial when working with any operating system. Whether you’re troubleshooting issues or simply want an overview of what’s running on your Ubuntu machine, knowing how to list all running processes from the terminal can be invaluable. This article will guide you through several methods to accomplish this task using different command-line tools available in Linux.

Introduction

Understanding and managing processes is a fundamental skill for any system administrator or power user working with Unix-like systems such as Ubuntu. A process refers to an instance of a program that is being executed by the operating system. Each running application on your computer, including background tasks like daemons and services, appears as a separate process.

This article focuses on listing all active processes from the terminal in Ubuntu using commands such as ps, top, htop, and pgrep. These tools provide varying levels of detail about running processes, allowing you to filter results based on specific criteria or view real-time activity across your system.

Why List Running Processes?

Before diving into how to list running processes, it’s important to understand why this is a necessary skill. Here are some reasons:

• Troubleshooting: Identifying processes that consume too much CPU or memory can help you diagnose and fix performance issues.

• Resource Management: Understanding which applications are using system resources allows for better management of your machine’s hardware.

• Security: Monitoring processes can help detect unauthorized activity, such as malicious software running on your system.

Prerequisites

Before we start listing running processes, ensure that your Ubuntu terminal is open and have the necessary permissions to execute commands. Most basic process monitoring tasks don’t require root privileges but advanced actions might need elevated access.

Opening Terminal in Ubuntu

To open a terminal window, you can either use the keyboard shortcut Ctrl + Alt + T or find “Terminal” in your applications menu. If using the menu approach, type “terminal” into the search bar and click on the application icon to launch it.

Listing Processes Using ps

The ps command is one of the most basic tools for viewing process information in Linux. It can display a snapshot of all running processes or specific details about certain processes based on criteria you provide.

Basic Usage

Run the following command in your terminal:

• -a: Shows all processes except those not associated with a terminal.
• -u: Displays user-oriented format, showing each process owner and their resources usage.
• -x: Includes processes without controlling terminals.

This command will list every running process along with details like the process ID (PID), username, CPU and memory usage, and more. You’ll see a detailed report similar to:

Filtering by User

If you want to list processes for a specific user, say username, use:

This command uses the pipe operator (|) to pass output from ps to grep, which filters the results based on your criteria.

Using top

While ps provides a static snapshot of processes, top offers real-time monitoring and is more interactive. It updates continuously and shows dynamic views of system activity.

Basic Usage

To start top, simply type:

When you run top, it will display a live view of the most resource-intensive processes first. The default sorting criterion is by CPU usage, but you can change this to prioritize memory usage or other criteria with Shift + R (for reverse order) and pressing 1 for showing threads.

Customizing Output

You can customize what information is displayed in top. For instance, press f to enter the fields menu where you can add/remove columns from display. To filter processes by user or name, use the u key followed by the username and n followed by process name respectively.

Using htop

Similar to top, but with an improved interface and more features, htop is a powerful tool for visualizing running processes on your system. Unlike top, it is not installed by default in Ubuntu, so you need to install it first:

Once installed, run htop from the terminal.

Basic Usage

Running this command will give a comprehensive real-time view of processes with additional features like dynamic process tree visualization and easy-to-use filtering options. You can interact with htop using various keys:

• F2: Open setup menu to configure display settings.
• F5/F6: Switch between different views showing system load, threads, or users’ processes specifically.
• k: Kill selected process.

Using pgrep

While not directly listing processes in the same way as other commands like ps, pgrep is a useful tool for searching for processes based on name patterns. This command can be especially handy when you’re looking to find specific processes and their PIDs.

Basic Usage

To list all process IDs of processes that match a given pattern, use:

Here -l option shows the associated command along with PID. If you only want PIDs without names, omitting this flag works too (pgrep <pattern>).

Advanced Usage

You can combine pgrep with other commands for more powerful process management. For example:

This command kills all processes matching the specified pattern.

Conclusion

In this article, we covered several methods to list running processes in Ubuntu from the terminal using various tools like ps, top, htop, and pgrep. Each of these commands serves different purposes and can be selected based on your specific needs - whether you’re looking for a quick snapshot or real-time monitoring capabilities.

Understanding how to use these commands effectively not only helps in managing system resources but also aids in troubleshooting issues related to software performance. Whether you are new to Linux administration or an experienced user, mastering the art of process management through terminal commands is essential for maintaining a smooth and efficient operating environment on Ubuntu systems.