Killing a Process in Linux

What killed my process and why?

If the user or sysadmin did not kill the program the kernel may have. The kernel would only kill a process under exceptional circumstances such as extreme resource starvation (think mem+swap exhaustion).

How to kill a process running on particular port in Linux?

Use the command

 sudo netstat -plten |grep java

used grep java as tomcat uses java as their processes.

It will show the list of processes with port number and process id

tcp6       0      0 :::8080                 :::*                    LISTEN      
1000       30070621    16085/java

the number before /java is a process id. Now use kill command to kill the process

kill -9 16085

-9 implies the process will be killed forcefully.

How to kill a process by its pid in linux

Instead of this:

proid= pidof $proceso

You probably meant this:

proid=$(pidof $proceso)

Even so,
the program might not get killed.
By default, kill PID sends the TERM signal to the specified process,
giving it a chance to shut down in an orderly manner,
for example clean up resources it's using.
The strongest signal to send a process to kill without graceful cleanup is KILL, using kill -KILL PID or kill -9 PID.

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I believe it's some kind of problem with the bash language (which I just started learning).

The original line you posted, proid= pidof $proceso should raise an error,
and Bash would print an error message about it.
Debugging problems starts by reading and understanding the error messages the software is trying to tell you.

Killing a process in linux

Linux supports the BSD style switches to the ps command (without the leading - ... dash/hyphen). If one supplies the hypen then the GNU coreutils version of ps (the one which is standard on mainstream Linux distributions) will attempt to interpret the switches as SysV compatible. This is the source of your error.

I'd recommend using the BSD form of the switches and look up the -o option to specify an output format consisting ONLY of the PID of the matching processes.

Also you're attempting to kill a zombie. As you've discovered that's a futile effort. A zombie is a placeholder in the process able for a process which is already dead. It remains in the process table until its parent process "reaps" its exit code. If the parent never does a wait() system call then the entry will stay there until after the parent is killed, at which point the zombie (and any other orphaned processes) will be inherited by the init process. The normal init under Linux (or any other form of UNIX) periodically reaps all dead processes (zombies).

Conceptually every process that exits on a UNIX/Linux system spends a small amount of time as a "zombie" ... that is there should always be a period of time between the process' termination and the time when some other process reads its exit value (even if only to discard it, as init does).

This question really should go on ServerFault

Find and kill a process in one line using bash and regex

In bash, you should be able to do:

kill $(ps aux | grep '[p]ython csp_build.py' | awk '{print $2}')

Details on its workings are as follows:

• The ps gives you the list of all the processes.
• The grep filters that based on your search string, [p] is a trick to stop you picking up the actual grep process itself.
• The awk just gives you the second field of each line, which is the PID.
• The $(x) construct means to execute x then take its output and put it on the command line. The output of that ps pipeline inside that construct above is the list of process IDs so you end up with a command like kill 1234 1122 7654.

Here's a transcript showing it in action:

pax> sleep 3600 &
[1] 2225
pax> sleep 3600 &
[2] 2226
pax> sleep 3600 &
[3] 2227
pax> sleep 3600 &
[4] 2228
pax> sleep 3600 &
[5] 2229
pax> kill $(ps aux | grep '[s]leep' | awk '{print $2}')
[5]+  Terminated              sleep 3600
[1]   Terminated              sleep 3600
[2]   Terminated              sleep 3600
[3]-  Terminated              sleep 3600
[4]+  Terminated              sleep 3600

and you can see it terminating all the sleepers.

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Explaining the grep '[p]ython csp_build.py' bit in a bit more detail:

When you do sleep 3600 & followed by ps -ef | grep sleep, you tend to get two processes with sleep in it, the sleep 3600 and the grep sleep (because they both have sleep in them, that's not rocket science).

However, ps -ef | grep '[s]leep' won't create a process with sleep in it, it instead creates grep '[s]leep' and here's the tricky bit: the grep doesn't find it because it's looking for the regular expression "any character from the character class [s] (which is s) followed by leep.

In other words, it's looking for sleep but the grep process is grep '[s]leep' which doesn't have sleep in it.

When I was shown this (by someone here on SO), I immediately started using it because

• it's one less process than adding | grep -v grep; and
• it's elegant and sneaky, a rare combination :-)

How to kill all processes with a given partial name?

Use pkill -f, which matches the pattern for any part of the command line

pkill -f my_pattern

Just in case it doesn't work, try to use this one as well:

pkill -9 -f my_pattern

How to kill a process on a port on ubuntu

You want to use backtick, not regular tick:

sudo kill -9 `sudo lsof -t -i:9001`

If that doesn't work, you could also use $() for command interpolation:

sudo kill -9 $(sudo lsof -t -i:9001)

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