How to Kill Linux Process
Killing a process is essential for any Linux system administrator or user. There are several ways to do this, and I’ll cover some of the most common and valuable methods.
Here’s a breakdown of what I’ll cover in this article:
Let’s get started!
In Linux, a process is an instance of a running program. Each process is assigned a unique process ID (PID) by the system, which can be used to identify and manipulate the process. Sometimes, it’s necessary to kill a process causing problems, whether hanging or consuming too many system resources. Killing a process can be done in several ways, and I’ll cover some of the most common methods below.
Overview of processes in Linux
Before we dive into the different ways to kill a process, let’s take a quick look at how processes are organized in Linux. Each process is part of a process tree, which starts with the init process (PID 1) and branches out from there. Each process has a parent process, except for the init process, which is the root of the tree.
Identifying processes to kill
Before killing a process, you need to identify the PID of the process you want to kill. There are several ways to do this, including:
- Using the ps command: This command lists all running processes on the system. By default, it only shows processes associated with the current terminal. To see all processes, use the -e option. The output will include the PID of each process.
- Using the top command: This command displays a real-time view of system processes, including PIDs, CPU usage, and memory usage.
- Using the htop command: This is a more advanced version of top that provides a more user-friendly interface and additional features.
Once you’ve identified the PID of the process you want to kill, you can use one of several commands to terminate it.
Using the kill command
The kill command is the most basic way to kill a process in Linux. Its syntax is as follows:
kill [signal] PID
The signal is optional and specifies the type of signal to send to the process. If no signal is specified, the default signal is SIGTERM, which politely asks the process to terminate. Here are some common signals:
- SIGTERM (15): polite termination request
- SIGKILL (9): forceful termination without cleanup
- SIGHUP (1): hang up signal, used to restart a process
To use the kill command, simply replace PID with the PID of the process you want to kill. For example:
This will send a SIGTERM signal to the process with PID 1234.
Using the pkill command
The pkill command is a more advanced version of the kill command that allows you to kill processes by name instead of PID. Its syntax is as follows:
pkill [signal] name
The name can be a partial or full match for the process name. For example:
This will send a SIGTERM signal to all processes with “Firefox” in their name.
Using the killall command
The killall command is similar to pkill but allows you to kill processes by name without specifying.
How to Kill a Process using a Linux GUI
Several GUI applications for Linux can be used to kill processes. Here are a few examples:
- System Monitor: This is a built-in application in many Linux distributions, including Ubuntu and Fedora. It provides a graphical interface for monitoring system resources and managing processes. To kill a process in System Monitor, simply select the process and click the “End Process” button.
- GNOME Task Manager: This built-in application in many Linux distributions provides a similar interface to System Monitor. To kill a process in GNOME Task Manager, select the process and click the “End Process” button.
- KSysGuard: This is a system monitor and process manager for the KDE desktop environment. It provides a detailed view of system resources and allows you to kill processes by selecting them and clicking the “Kill” button.
- xkill: This simple command-line utility can be used to kill a misbehaving GUI application. To use xkill, simply run the command and click on the application window you want to kill. This will send a SIGKILL signal to the process associated with that window.
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