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How To Kill Processes in Ubuntu as a Non-Root User

Ubuntu 6

In this article, we will delve into the process of terminating or ‘killing’ processes in Ubuntu as a non-root user. This is a crucial skill for managing and maintaining your Ubuntu system, especially when dealing with unresponsive or resource-hogging applications.

Quick Answer

To kill processes in Ubuntu as a non-root user, you can use commands such as kill, pkill, killall, and xkill. These commands allow you to terminate processes either by their Process ID (PID) or by their name. However, it’s important to exercise caution while killing processes to avoid system instability or data loss.

Understanding Processes

Before we dive into the methods of killing processes, it’s essential to understand what a process is. A process is an instance of a running program. When you open an application, a process is created that runs in the background or foreground of your system.

Viewing Active Processes

The first step in killing a process is identifying the process that needs to be terminated. Ubuntu provides several ways to view active processes:

  • ps command: The ps command is a powerful tool for displaying active processes. The command ps -ef will display a detailed list of all current processes.
  • pgrep command: If you are looking for processes owned by a specific user, the pgrep command can be handy. pgrep -l -u username will list all processes owned by the specified user.
  • htop command: For a more interactive view, you can use the htop command. If not already installed, you can install it using sudo apt-get install htop.

Killing Processes

Once you’ve identified the process you wish to terminate, you can use several commands to kill it:

  • kill command: The kill command is used to send a signal to a process. Most commonly, it’s used to terminate processes. The syntax is kill [signal or option] PID. The PID (Process ID) is a unique number that identifies a process. If you don’t specify a signal, the TERM signal is sent, which terminates the process. For example, kill 1234 will send the TERM signal to the process with PID 1234.
  • pkill and killall commands: These commands are used to kill processes by name. pkill firefox will kill all processes named ‘firefox’. The killall command works similarly.
  • xkill command: If you are using the X Window System, you can use the xkill command to terminate a process by clicking on its window. However, this may not work for non-window processes or processes not related to the X server.

Caution While Killing Processes

While killing processes can be a useful tool for managing your system, it should be used with caution. Killing critical system processes or processes performing important tasks can cause system instability or data loss. Always ensure you are terminating the correct process.


In conclusion, Ubuntu provides a variety of tools for managing processes. Whether you are a system administrator or a regular user, knowing how to kill processes is a vital skill. Remember to use these commands responsibly and only when necessary.

How can I identify the Process ID (PID) of a specific process?

To identify the PID of a specific process, you can use the ps command with the aux option. For example, ps aux | grep process_name will display the process details along with its PID.

Can I kill multiple processes at once?

Yes, you can kill multiple processes at once using the kill command followed by a space-separated list of PIDs. For example, kill 1234 5678 9012 will terminate the processes with PIDs 1234, 5678, and 9012.

How can I forcefully terminate a process that is not responding to the TERM signal?

If a process is not responding to the TERM signal, you can use the kill -9 PID command to send the KILL signal, which forcefully terminates the process. However, this should be used as a last resort, as it doesn’t allow the process to clean up properly.

Is it possible to kill processes owned by other users?

Non-root users can only kill processes that they own. To kill processes owned by other users, you need root or superuser privileges.

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