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Questions tagged [kill]

kill - Send a specified signal to a process or process group.

451
votes
14answers
515k views

What if 'kill -9' does not work?

I have a process I can't kill with kill -9 <pid>. What's the problem in such a case, especially since I am the owner of that process. I thought nothing could evade that kill option.
393
votes
9answers
157k views

When should I not kill -9 a process?

I am always very hesitant to run kill -9, but I see other admins do it almost routinely. I figure there is probably a sensible middle ground, so: When and why should kill -9 be used? When and why ...
182
votes
8answers
494k views

How to terminate a background process?

I have started a wget on remote machine in background using &. Suddenly it stops downloading. I want to terminate its process, then re-run the command. How can I terminate it? I haven't closed ...
126
votes
7answers
20k views

How to kill a runaway cat?

Many times I accidentally run the cat command on files that have contents up to few thousand lines. I try to kill the cat command with Ctrl+ C or Ctrl+Z, but both only take effect after the total ...
91
votes
3answers
15k views

How does Linux “kill” a process?

It often baffles me that, although I have been working professionally with computers for several decades and Linux for a decade, I actually treat most of the OS' functionality as a black box, not ...
64
votes
13answers
163k views

Kill many instances of a running process with one command

Suppose I have a thousand or more instances of any process (for example, vi) running. How do I kill them all in one single shot/one line command/one command?
63
votes
2answers
30k views

Will Linux start killing my processes without asking me if memory gets short?

I was running a shell script with commands to run several memory-intensive programs (2-5 GB) back-to-back. When I went back to check on the progress of my script I was surprised to discover that some ...
61
votes
5answers
146k views

How do I kill all screens?

I accidentally created over 1000 screens. How do I kill them all with one command? (Or a few)
57
votes
3answers
23k views

What does `kill -0` do?

I recently came across this in a shell script. if ! kill -0 $(cat /path/to/file.pid); then ... do something ... fi What does kill -0 ... do?
50
votes
4answers
18k views

Linux: Kill process based on arguments

How can I kill a process based on its command line arguments? killall, pgrep, and pkill seem to only work based on the process name. I need this to be able to differentiate between a number of ...
48
votes
4answers
60k views

Default exit code when process is terminated?

When a process is killed with a handle-able signal like SIGINT or SIGTERM but it does not handle the signal, what will be the exit code of the process? What about for unhandle-able signals like ...
46
votes
5answers
96k views

Kill all descendant processes [duplicate]

I'm writing an application. It has the ability to spawn various external processes. When the application closes, I want any processes it has spawned to be killed. Sounds easy enough, right? Look up ...
43
votes
4answers
21k views

What's the difference between pkill and killall?

I know that pkill has more filtering rules than killall. My question is, what is the difference between: pkill [signal] name and killall [signal] name I've read that killall is more effective and ...
41
votes
6answers
7k views

Does pressing ctrl-c several times make the running program close more quickly?

I often start to read a huge file and then want to quit after a while, but there is a lag from pressing Ctrl+C to the program stops. Is there a chance of shortening the lag by pressing the Ctrl+C key ...
41
votes
1answer
5k views

Why is the UNIX system call kill named 'kill'?

I am curious about the history of the name, it seems to me that the 'kill' system call could have been named 'signal', and the 'signal' system call could have been named 'handle'. I was wondering ...
39
votes
9answers
9k views

How can I kill a process and be sure the PID hasn't been reused

Suppose, for example, you have a shell script similar to: longrunningthing & p=$! echo Killing longrunningthing on PID $p in 24 hours sleep 86400 echo Time up! kill $p Should do the trick, ...
39
votes
4answers
351k views

How do I exit or cancel a bad bash command?

I expect to get some flak for this, but I can't find the answer anywhere. It seems like it should be so obvious. Sometimes, when I type a bad command in a bash terminal, the cursor just jumps down to ...
38
votes
1answer
4k views

What does a program do when it's sent SIGKILL signal?

When I used killall -9 name to kill a program, the state become zombie. Some minutes later, it stopped really. So, what's happening during those minutes?
34
votes
7answers
32k views

How can I close a terminal without killing its children (without running `screen` first)?

sometimes I run an app in the gnome-terminal, but then I suddenly have to restart gnome or something. I guess the answer to the question is also useful then I want to disconnect from SSH where ...
32
votes
3answers
49k views

Where can I see a list of kernel killed processes?

Is there some way I can check which of my processes the kernel has killed? Sometimes I log onto my server and find that something that should've run all night just stopped 8 hours in and I'm unsure if ...
28
votes
3answers
15k views

How signals work internally?

In general, to kill processes we generate signals like SIGKILL,SIGTSTP etc. But how is it known who ordered that particular signal, who has sent it to a particular process, and in general how do ...
28
votes
2answers
48k views

Program behavior when kill -HUP is recieved?

Is there a way to find out what will program do when it receives kill signal HUP? Without simply running the command ofc :D For example, killall -HUP pppd will restart pppd killall -HUP firefox ...
28
votes
1answer
10k views

Difference between less violent kill signal -HUP (1) -INT (2) and -TERM (15)

Apart from the most violent kill -9 (SIGKILL), I don't quite understand the difference between the 3 other common signals (here) -HUP (1), -INT (2), and -TERM (15). In which scenarios would one work ...
28
votes
1answer
7k views

How does systemd survive a kill -9?

Between the recent "Why does 'kill -9 0' end my console session" and "How to get a kernel panic" questions, I got a bur under my saddle and tried kill -9 1 on a mostly up-to-date Arch linux laptop. I ...
28
votes
2answers
29k views

What is the difference between kill , pkill and killall

I am familiar with kill command , and most of the time we just use kill -9 to kill a process forcefully , there are many other signals that can be used with kill. But i wonder what are the use cases ...
27
votes
2answers
56k views

How can I kill a <defunct> process whose parent is init?

Transmission is intermittently hanging on my NAS. If I send SIGTERM, it doesn't disappear from the process list and a <defunct> label appears next to it. If I send a SIGKILL, it still doesn't ...
26
votes
5answers
21k views

Exit Google Chrome from terminal

Is there a way to cause google-chrome to quit, from the terminal, besides using killall google-chrome? I would like to be able to close it from a script without killing it.
26
votes
2answers
2k views

When you try to terminate a process for good, which option for “kill” should you use?

I am getting a lot of mixed messages from people, and was wondering if it there really is not much of a difference in what you use. kill 'x' killall 'x' kill -9 'x' These are some options I've been ...
24
votes
5answers
12k views

How to make `xargs` ignore child's exit and keep processing further

I sometimes run long xargs jobs overnight and it is really annoying to discover in the morning that xargs died somewhere in the middle, for example because of a segmentation fault in one single ...
23
votes
7answers
119k views

Fix “firefox is already running” issue in Linux

I am trying to open Firefox in CentOS, but I'm getting the following message: Firefox is already running but is not responding and Firefox doesn't open. I tried this in command line: kill ...
23
votes
2answers
4k views

why would typing Ctrl+c twice stop a running process in Linux?

There are Linux programs, for example vlc, that recommend typing ctrl+c twice to kill their execution from a terminal if the program didn't stop after the first one. Why would typing ctrl+c twice ...
22
votes
2answers
5k views

How can I kill minerd malware on an AWS EC2 instance? (compromised server)

I found malware on my ec2 instance which was continuously mining bitcoin and using my instance processing power. I successfully identified the process, but was unable to remove and kill it. I ran ...
22
votes
7answers
18k views

pgrep and pkill alternatives on mac os x?

Are there alternatives to pgrep and pkill commands on Mac OS X or should I just create aliases for them using other commands available for me?
22
votes
2answers
5k views

Why can't I kill a SIGSTOP'd process with a SIGTERM, and where is the pending signal stored?

I am using Debian stretch (systemd). I was running the rsyslog daemon in foreground using /usr/sbin/rsyslogd -n and I did a Ctrl+Z to stop it. The state of the process changed to Tl (stopped, ...
22
votes
5answers
13k views

How to soft kill gui applications via terminal?

Is there a way to close a GUI application in friendly "please quit yourself now" way, without graphical access to the applications window? For example, if Gnome/X display crashes to black, I'd like ...
21
votes
4answers
18k views

Kill process spawned by ssh when ssh dies

This is a question that has been addressed several times, not only here, but also in other sites of the stack exchange network (e.g. How to make ssh to kill remote process when I interrupt ssh itself? ...
20
votes
5answers
23k views

How can I kill and wait for background processes to finish in a shell script when I Ctrl+C it?

I'm trying to set up a shell script so that it runs background processes, and when I Ctrlc the shell script, it kills the children, then exits. The best that I've managed to come up with is this. It ...
19
votes
4answers
46k views

How to kill multiple processes

to find the PID of the process to kill use : pgrep <process command> I then use the kill command to kill the PID returned by pgrep <process command> kill <PID> Can these ...
18
votes
4answers
31k views

Alternative way to kill a zombie process

I just noticed some zombie processes on CentOS 6.8(Final), tried to kill them but they are still there: [root@host user]# ps -ef | grep git tomcat 746 1 0 Jul18 ? 00:00:00 git clone ...
18
votes
4answers
34k views

How to kill a process with a single command?

I want to kill a process, after finding the id in a single step. I currently use these two commands: pidof <name> kill <#number_which_is_result_of_command> How can I write a single ...
18
votes
2answers
3k views

How to terminate Linux tee command without killing application it is receiving from

I have a bash script that runs as long as the Linux machine is powered on. I start it as shown below: ( /mnt/apps/start.sh 2>&1 | tee /tmp/nginx/debug_log.log ) & After it lauches, I can ...
18
votes
2answers
5k views

Why does `kill -l` not list signal numbers of 32 and 33?

Executing kill -l on linux gives: 1) SIGHUP 2) SIGINT 3) SIGQUIT 4) SIGILL 5) SIGTRAP 6) SIGABRT 7) SIGBUS 8) SIGFPE 9) SIGKILL 10) SIGUSR1 11) SIGSEGV ...
18
votes
1answer
17k views

What does kill 0 do actually? [closed]

In the man page, it says: kill [ -s signal | -p ] [ -a ] [ -- ] pid ... pid... Specify the list of processes that kill should signal. Each pid can be one of five things: 0 All ...
17
votes
2answers
91k views

How to kill a process that says “Operation not permitted” when attempted?

I have a process I would like to kill: computer@ubuntu:~$ ps aux | grep socat root 2092 0.0 0.0 5564 1528 pts/1 T 14:37 0:00 sudo socat TCP:xxx.17.29.152:54321 PTY,link=/dev/ttyGPS0,...
17
votes
3answers
3k views

Is there an upper limit to the number of zombie processes you can have?

I used to work with an HP-UX system and the old admin told me there is an upper limit on the number of zombie processes you can have on the system, I believe 1024. Is this a hard fact ceiling? I ...
16
votes
4answers
70k views

Finding the ID of a process and killing it

When ever I need to kill a background process I do ps -e | grep <process_name> Which prints something like this 1766 ? 00:00:13 conky , Then I use the process ID to kill it like so kill 1766 . ...
16
votes
2answers
13k views

Why does bash show 'Terminated' after killing a process?

Here is the behaviour I want to understand: $ ps PID TTY TIME CMD 392 ttys000 0:00.20 -bash 4268 ttys000 0:00.00 xargs $ kill 4268 $ ps PID TTY TIME CMD 392 ttys000 ...
16
votes
2answers
18k views

Kill a suspended process?

I was slightly confused by: % vim tmp zsh: suspended vim tmp % kill %1 % jobs [1] + suspended vim tmp % kill -SIGINT %1 % jobs [1] + suspended vim tmp % kill -INT %1 % jobs [1] + suspended ...
15
votes
3answers
851 views

ORing with true in a command over ssh

When I try to run pkill -f remotely via ssh, and try to discard the possible error code (to go on with the rest of my script even if no process is found), || true does not behave as I expect. $ pkill ...
15
votes
6answers
116k views

Kill only one Java process

I usually run few Java applications, one for server running locally and other for some IDE like NetBeans. And from time to time, after lots of redeployments, my server get stuck on ...