> ## Content Index > Fetch the complete content index at: https://linuxhandbook.com/llms.txt > Use this file to discover other available public pages before exploring further. # Kill a Process in Linux Command Line - URL: https://linuxhandbook.com/kill-process/ - Published: 2022-05-26T05:37:21.000Z - Updated: 2024-06-14T08:36:19.000Z - Description: Found a misbehaving process? Here's how to teach a lesson to it by terminating it using various commands. - Author: Abhishek Prakash - Tags: Process Handling, Quick Tip, #cli, #docs-col It has been an awesome day on your Linux system, and suddenly a process starts to slow down the whole computer. It is not that important, and you want to stop its execution. If the command/process is running in the foreground, you can use the Ctrl+C terminal shortcut. However, if the process is not visible ([running in the background](https://linuxhandbook.com/run-process-background/)), you can use dedicated commands to 'kill it'. The term "killing a process" refers to stopping a process mid execution. If you [know the process ID](https://linuxhandbook.com/find-process-id/) (PID), you can use the kill command like this: ```bash kill ``` In the above syntax, `signal` refers to the kill signal you want to send for termination and `PID` refers to the ID of the process. There is also a killall command and I'll discuss both [kill and killall commands](https://linuxhandbook.com/kill-vs-killall/) in this article. Before you start killing processes, you should know a few things. Such as what termination signals are available, how to find PID etc. Let's start with the signals first. ## Termination signals in Linux When a process is terminated by the OS or by the user i.e. the process did not finish on its own, it is sent a terminal signal. Below are the available [termination signals in Linux](https://linuxhandbook.com/termination-signals/): | Signal | Numerical Value | Description | | ------- | --------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | SIGHUP | 1 | Signal Hangup: Sent to a process when the terminal controlling it is closed. | | SIGINT | 2 | Signal Interrupt: The signal sent to a process when a user terminates a process. (eg Ctrl + X) | | SIGKILL | 9 | Signal Kill: The signal that immediately quits a process, without allowing it to save its current state. | | SIGTERM | 15 | Signal Terminate: Sent to the signal to request termination of process. This signal can be ignored by a process. But this is the preferred way of terminating a process as it can release the resources when the process receives SIGTERM. | | SIGSTOP | 19 (for x86, ARM and most others)17 (for Alpha)23 (for MIPS)24 (for PARISC) | Signal Stop: Signal for stopping a process, but to be resumed at a later time. | It is most likely that you'll be using signals 9 and 15\. Read more about the [difference between SIGKILL and SIGTERM](https://linuxhandbook.com/sigterm-vs-sigkill/). [What is SIGTERM? What’s the difference between SIGKILL & SIGTERM?Both SIGTERM and SIGKILL are used for killing a process in Linux. But you should prefer using SIGTERM. Here’s why!![](https://linuxhandbook.com/favicon.png)Linux HandbookAbhishek Prakash![](https://linuxhandbook.com/content/images/2020/06/dont_sigkill_use_sigterm.jpg)](https://linuxhandbook.com/sigterm-vs-sigkill/) ## Getting the PID of a process You also need to know the details of the process you want to terminate. With kill command, you must provide the id of a process (PID). You can get the PID from the [process name](https://linuxhandbook.com/process-name-from-pid/): ``` pidof exact_process_name ``` ## Terminating a process in the Linux command line Let's see the kill command first as you'll be using it more than killall. ### Using kill command The `kill` command requires that you know the ID of a process that you want to kill and, optionally, the termination signal. To simply kill a command, use the following syntax: ```bash kill [signal] ``` Sending a termination signal to a PID is optional, and if no signal is provided, `kill` defaults to sending SIGTERM (`15`), ending in a graceful termination of said process. I started a background process of [sleep command](https://linuxhandbook.com/bash-sleep/) (and it gave me a PID). Let's try killing it using the `kill` command. Killing this particular instance of `sleep` would look like the following: ```bash $ sleep 120 & [1] 125686 $ kill 125686 [1] + terminated sleep 120 ``` If I wanted to use a termination signal, I could either use the numerical value or the signal itself: ```bash $ sleep 120 & [1] 125746 $ kill -SIGKILL 125746 [1] + killed sleep 120 ####----##-----#### $ sleep 120 & [1] 125759 $ kill -9 125759 [1] + killed sleep 120 ``` 🗒️ If no signal is specified with the kill command, SIGTERM (15) is used by default. ### Using killall command If you do not know what the PID of a process is, or if the said process has multiple child processes, and you want to kill the child processes and the parent process at once, you can use `killall` command. ```bash killall [signal] ``` Similar to `kill` command, specifying a termination signal is optional. When no termination signal is specified, `killall` will send SIGTERM (`15`) to gracefully shut down said process. To demonstrate the use of `killall`, I want to kill two running sleep commands. ```bash $ sleep 120 & [1] 18609 $ sleep 2000 & [2] 18612 $ killall sleep [1]- Terminated sleep 120 [2]+ Terminated sleep 2000 ``` Additionally, you can use the `-e` flag to find an exact match of the process name. [Kill vs Killall: Difference Between the Two Linux CommandsBoth kill and killall commands are used for force stopping (killing) processes in Linux. Learn the difference between the two similar commands.![](https://linuxhandbook.com/favicon.png)Linux HandbookAbhishek Prakash![](https://linuxhandbook.com/content/images/2022/03/difference-between-kill-and-killall-commands.png)](https://linuxhandbook.com/kill-vs-killall/) ### Using pkill command An alternative command to `kill` is the `pkill` command. It is a "combination" of [pgrep](https://linuxhandbook.com/pgrep/) and `kill` command. The `killall` kills all the processes that have a matching name. On the other hand, `pkill` uses pattern matching to match processes and kills them. Below is the syntax: ```bash pkill [options] pattern ``` A few useful options available in `pkill` command as following: - `-u` : Processes owned by a particular owner - `-x` : Processes that match pattern exactly - `-signal` : Specify a termination signal (default is SIGTERM) Assuming I have a user `guest` on my computer who should not have any processes running currently, and if there are, I want to terminate them. How can I do that? ```bash $ ps aux | grep sleep guest 126061 0.0 0.0 6664 428 pts/3 S 10:14 0:00 sleep 50 $ sudo pkill -u guest ``` Note that I used `sudo` because I was dealing with processes that did not belong to my user. With this article, you learned 3 different commands for killing a process in Linux. I feel it will be the kill command that you more than the others. Am I right?