kill<\/strong> command to send a signal. The following is its basic syntax:<\/p>kill [signal] PID<\/pre>For example, to ask the process to end with the default SIGTERM<\/strong> signal and PID 1234<\/strong>, execute:<\/p>kill -15 1234<\/pre>If the process does not respond to SIGTERM<\/strong>, try using the SIGKILL<\/strong> signal to terminate it forcefully:<\/p>kill -9 1234<\/pre>You can also send other signals based on your specific needs, such as:<\/p>
kill -2 1234 # Sends SIGINT<\/pre>kill -1 1234 # Sends SIGHUP<\/pre>How to kill multiple processes<\/h3>
There might be situations where you need to terminate multiple processes simultaneously. Fortunately, the kill<\/strong> command can also send a signal to multiple PIDs at once, making it a powerful tool for managing Linux processes.<\/p>However, be cautious, as some processes might depend on others. Killing a parent process can also terminate other processes.<\/p>
The basic syntax for killing multiple processes is:<\/p>
kill [signal] PID1 PID2 PID3<\/pre>Here’s an example of ending processes with PIDs 1234<\/strong>, 5678<\/strong>, and 91011<\/strong> using SIGTERM<\/strong>:<\/p>kill -15 1234 5678 91011<\/pre>To send a signal to all processes in a group, use the negative PID of the group leader:<\/p>
kill -15 -1234<\/pre>This kills all processes in the group led by PID 1234<\/strong>.<\/p>How to kill a process with the pkill command<\/h3>
The pkill<\/strong> command lets you kill processes by name without first identifying their PIDs, making it simpler and more convenient to use than kill<\/strong>. It’s also faster to type and execute, especially when dealing with multiple instances of the same process.<\/p>Below is the basic syntax of pkill<\/strong>:<\/p>pkill [signal] [process name]<\/pre>For example, to kill a process named nginx<\/strong>, run:<\/p>pkill -SIGTERM nginx<\/pre>If you want to terminate processes owned by a specific user:<\/p>
pkill -u john<\/pre>For instance, to end processes associated with a terminal pts\/1<\/strong>:<\/p>pkill -t pts\/1<\/pre>You can also kill all processes in a specific process group, for example, PGID 1234<\/strong>:<\/p>pkill -g 1234<\/pre>To terminate the newest or oldest instance of a process, type the following:<\/p>
pkill -n nginx # Kill the newest instance of nginx<\/pre>pkill -o nginx # Kill the oldest instance of nginx<\/pre>You can also combine multiple options to match processes based on specific criteria. For example, to kill processes from user john<\/strong> on terminal pts\/1<\/strong> in process group 1234<\/strong> at once, execute the following:<\/p>pkill -u john -t pts\/1 -g 1234<\/pre>How to kill a process with the killall command<\/h3>
killall<\/strong> terminates all instances of a process by name and can target processes based on age, user, and running time.<\/p>It’s ideal to manage processes with the same name across the system, compared to kill<\/strong> for individual processes and pkill<\/strong> for selectively managing multiple instances of a process.<\/p>The basic syntax of the killall<\/strong> command is:<\/p>killall [options] [process_name]<\/pre>Here are some of its primary uses:<\/p>
killall nginx # Terminates all instances of nginx<\/pre>killall -s SIGKILL nginx # Forcefully kills all instances of nginx<\/pre>killall -u john nginx # Ends all nginx processes owned by the user john<\/pre>If you want to kill processes that have been running for a specific duration:<\/p>
killall -o 1h nginx<\/pre>This kills all nginx<\/strong> processes running for more than one hour.<\/p>To kill all instances of a process except a specific one:<\/p>
killall -v -I nginx<\/pre>You can exclude a specific nginx<\/strong> process from being killed with the above command.<\/p>Furthermore, to kill processes based on their CPU load or memory usage:<\/p>
killall -i -s SIGKILL nginx<\/pre>This sends an interactive prompt before killing each nginx<\/strong> process so you can confirm or deny each action.<\/p>How to kill a process with the xkill command<\/h3>
The xkill<\/strong> command is designed for GUI-based environments like a Linux-installed laptop. With it, you can kill applications that have frozen or don’t respond to standard termination commands with a simple click.<\/p>Here are some scenarios where xkill<\/strong> proves handy:<\/p>\n- Unresponsive applications<\/strong>. If an application becomes unresponsive and you cannot close it using standard methods.<\/li>\n\n\n\n
- Frozen GUI elements<\/strong>. When certain GUI elements, such as windows or dialogs, freeze and don’t allow interaction.<\/li>\n\n\n\n
- Quick termination<\/strong>. When you need to terminate a specific window or application quickly and easily without looking up its PID.<\/li>\n<\/ul>
To use xkill<\/strong>, enter this command in your terminal:<\/p>xkill<\/pre>After executing this command, your mouse cursor will change to an ×<\/strong> icon. Then, move the cursor to the window of the unresponsive application and right-click on it. This will immediately kill the selected process.<\/p>Alternatively, if you know the unresponsive application’s window ID, type:<\/p>
xkill -id <window_id><\/pre>With this command, you can target and kill a specific window directly.<\/p>
Please note that xkill<\/strong> doesn’t natively support killing by class or name. However, you can use other tools in conjunction with it to achieve similar results. For example, use wmctrl<\/strong> to list windows and their IDs, and then run xkill<\/strong> with the appropriate ID.<\/p>To install wmctrl<\/strong>, run:<\/p>sudo apt-get install wmctrl<\/pre>Once done, list all windows and their IDs:<\/p>
wmctrl -l<\/pre>The output will look something like this:<\/p>
0x03c00003 0 hostname Firefox
0x04a00004 0 hostname Terminal
0x05000005 0 hostname Code<\/pre>Then run xkill<\/strong> with the desired ID, for instance:<\/p>xkill -id 0x03c00003<\/pre>How to kill a process with the top command<\/h3>
Last but not least, the top<\/strong> command provides a real-time, interactive view of resource usage and running processes. It’s handy for identifying and terminating processes that consume excessive resources or become unresponsive.<\/p>As previously explained, you can type top<\/strong> in your terminal to start it. To navigate through the list of processes, use the arrow keys<\/strong>. Press Shift + P<\/strong> to sort processes by CPU usage, while Shift + M<\/strong> sorts them by memory usage.<\/p>...
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
1 root 20 0 169364 8824 6508 S 0.0 0.2 0:05.14 systemd
512 user 20 0 120364 6024 2508 S 1.0 0.1 0:02.04 firefox
789 user 20 0 140364 7624 3208 R 2.0 0.3 0:03.22 chrome
...<\/pre>Once you’ve identified the process you want to end, press K<\/strong>.<\/p>top<\/strong> will prompt you to enter the process’ PID you wish to kill. Then, you need to specify the signal to send to the process.<\/p>Press Enter<\/strong> to send the default SIGTERM<\/strong> signal, or type a different signal number if required.<\/p>For instance, to kill the chrome<\/strong> process with PID 789 <\/strong>using SIGKILL<\/strong>:<\/p>k
PID to kill: 789
Send signal (15): 9<\/pre>Additionally, to view processes owned by a specific user, start top<\/strong> with the -u<\/strong> option like the following:<\/p>top -u john<\/pre>You can also customize the columns displayed within top<\/strong> by pressing
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