How to Kill a Background Process in Linux

Linux is a powerful and flexible operating system that is popular among developers and system administrators. One of benefits of Linux is that it allows users to run multiple processes simultaneously, which can increase productivity and efficiency. However, sometimes a background process may become unresponsive or cause system performance issues. In such cases, it becomes necessary to kill process. In this article, we will discuss how to kill a background process in Linux.

Understanding Background Processes

Before we dive into process of killing a background process, it's essential to understand what background processes are and why they are important.

In Linux, a process is a running instance of a program or application. A background process is a process that runs in background, without requiring user input or interaction. These processes typically perform tasks that don't require user interaction or are scheduled to run at a later time.

Background processes are essential in Linux as they enable users to run multiple tasks simultaneously. For example, a user can start a download and continue working on another task without interruption.

However, sometimes a background process can cause system performance issues or become unresponsive. In such cases, it becomes necessary to kill process.

Identifying Background Processes

Before killing a background process, you need to identify process. You can use following command to list all processes running on your system −

ps -aux

This command will list all processes running on your system, along with their process ID (PID) and other details. PID is a unique identifier for each process, which you will need to kill process.

Once you have identified process, you can use following command to send a signal to process −

kill [signal] [PID]

The signal is a message that tells process what to do. default signal is SIGTERM, which tells process to terminate gracefully. However, if process is unresponsive or causing system performance issues, you may need to send a different signal, such as SIGKILL, which forces process to terminate immediately.

Killing a Background Process

To kill a background process, follow these steps −

• Step 1 − Identify process Run ps -aux command to identify process you want to kill. Make a note of process ID (PID).

• Step 2 − Send a signal to process Use kill command to send a signal to process. syntax for kill command is as follows −

kill [signal] [PID]

For example, to send a SIGTERM signal to a process with PID 1234, use following command −

kill 1234

Alternatively, you can use following command to send a SIGKILL signal to process −

kill -9 1234

• Step 3 − Verify process has been killed Run ps -aux command again to verify that process has been killed. If process is still running, repeat steps 2 and 3 with a different signal.

Killing Multiple Background Processes

If you need to kill multiple background processes, you can use killall command. killall command allows you to kill all processes with a particular name. For example, to kill all instances of firefox process, use following command −

killall firefox

You can also use -9 option to send a SIGKILL signal to processes −

killall -9 firefox

Killing Background Processes with System Monitor

If you prefer a graphical interface, you can use System Monitor application to kill background processes. To open System Monitor, follow these steps −

• Step 1 − Open System Monitor Open System Monitor application from Applications menu.

• Step 2 − Identify process Click on Processes tab to view all running processes. You can sort processes by clicking on column headings.

• Step 3 − Kill process Select process you want to kill and click End Process button. This will send a SIGTERM signal to process. If process does not terminate within a few seconds, you can click Force Quit button to send a SIGKILL signal to process.

Additional Methods to Kill a Background Process in Linux

Apart from using kill command and System Monitor application, there are a few other methods that you can use to kill a background process in Linux −

Pkill Command

The pkill command is similar to killall command, but it allows you to kill processes based on their name or other attributes. For example, to kill all processes with name firefox, use following command −

pkill firefox

You can also use -f option to match full command line instead of just process name −

pkill -f firefox

Xkill Command

The xkill command is a graphical utility that allows you to kill a process by clicking on its window. To use xkill command, open a terminal window and type following command −

xkill

Your cursor will change to a skull and crossbones icon. Click on window of process you want to kill, and process will be terminated.

Htop Command

The htop command is an interactive process viewer that allows you to view and manage running processes. To install htop, run following command −

sudo apt-get install htop

To launch htop, type following command −

htop

You can navigate through processes using arrow keys and use F9 key to send a signal to selected process. Select process you want to kill and press F9 key. You can then select signal you want to send to process, such as SIGTERM or SIGKILL.

Conclusion

Killing a background process in Linux is a simple process that can be done using kill command or System Monitor application. It's important to identify process before attempting to kill it and to use appropriate signal for situation. By following these steps, you can efficiently manage processes running on your system and improve system performance.