Develop Reference

kill a java process in Linux

I have a BI application (looker) runs on a linux VM.
tobe able to restart the service, I need to clear the existing java process.
In below screenshot, after run below script, there is a java process, but not showing in the list when I run jps script. What's the reason? and how can I properly terminate this java process?
ps aux | grep java

Have you tried these ?
killall java
or
kill $(pidof java)

As you can see from your image, the process id is changing each time 9287 / 9304 and represents | grep java - and not a java VM!
A common fix is to filter the ps results for not matching | grep -v, such as:
ps aux | grep java | grep -v --regexp=grep.\*java
If there are results above you could append commands to read the process ids and kill command:
kill -TERM $(ps aux | grep java | grep -v --regexp=grep.\*java | awk '{print $2}')
Note: the above will kill all processes with "java" in name so is not very useful if there are multiple java services for same account. You may need to add filter for specific Java VMs.

How to stop the process from running?

This question might be a bit similar to this or this question.
How do I stop a particular .jar file from running in Mac OS? When I open up the activity monitor, it does not show the process listed. But I am sure it is running because when I visit the localhost (I have developed a .jar from a Spring Boot application), I can still see the welcome message!
Could you please let me know how I could stop a particular .jar file from executing? Thanks.

You can use jps to get the pid (and jar name), awk to parse the pid and then kill it. Like, (with bash or similar)
kill -9 $(jps | grep -i "thejar.jar" | awk '{print $1}')
or
kill -9 `jps | grep -i "thejar.jar" | awk '{print $1}'`
The -i option to grep makes it case insensitive. Omit if that is not needed.

Step1: ps -aux | grep xxx, xxx is the name of .jar
Step2: kill -9 pid, pid you can get from the first command.

Getting PID of a process that has just started

I am working on a Gradle Java project. Which starts Tomcat for testing and stops it later.
I am supposed to kill this Tomcat instance when the test fails.
I tried using "ps aux| grep tomcat | grep -v grap | awk {print $2}" command to get the process id and kill the process.
But on Production, there will be so many Tomcat processes running simultaneously by many users, I just want the tomcat process started by my build.gradle for test execution.
So how can I accomplish the task? Please provide me some guidelines.

You need to find a unique string in the output of 'ps aux' which differentiates your test tomcat and others'.
I currently use the below script to run 'shutdown.sh' first and then kill the PID as most of the times, the application stops but the process does not stop.
PID=`ps -ef | grep $JAVA_HOME/bin/java | grep "$TOMCAT_LOC"/conf | grep -v grep | awk '{ print $2 }'`
if [ $PID ]; then
echo tomcat is running with PID:$PID.
# Stop or Kill running Tomcat
if [[ -f $TOMCAT_LOC/bin/shutdown.sh ]]; then
[[ ! -x $TOMCAT_LOC/bin/shutdown.sh ]] && chmod a+x $TOMCAT_LOC/bin/shutdown.sh
$TOMCAT_LOC/bin/shutdown.sh >>/dev/null
sleep 20
fi
kill -9 $PID
sleep 3
else
echo tomcat is not running
fi
You may also look at configuring a PID file by editing the 'catalina.sh' which you can read later to find out your PID.
# CATALINA_PID (Optional) Path of the file which should contains the pid
# of the catalina startup java process, when start (fork) is
# used

Java JRE has tool called jps in $JAVA_HOME/bin folder.
It's similar to unix ps command but for java only.
You can use it to determined exac java process you need.
Using this tool is more recommended and actually it is more useful, when you have more than one java applications is running on your host...
for example I have running h2 database and many other apps, but wanna kill only h2, so I can use jps to get it PID
$ jps
17810 GradleDaemon
17798 GradleWrapperMain
17816 h2-1.4.197.jar
17817 GradleDaemon
17818 GradleDaemon
18011 Jps
16479
and then just kill needed process:
kill -9 17816
and all other java apps will continue work normally. I not sure about tomcat, but I think it can be done in similar way, something like that:
kill -9 $(jps | grep tomcat | awk '{print $1}')
Lastly, little bit offtopic, but a specially to your case: correct way would be using start/stop/restart scripts provided by tomcat

The correct way to terminate a Tomcat instance is via its own shutdown command. You should not be thinking of processes, or PIDs, or kills, at all.

so if you want to kill tomcat from that user from which you have logged in then try following and let me know if this helps you.
ps -ef | grep -v grep | grep `whoami` | grep tomcat
So by ps -ef I am listing all the processes then grep -v grep will remove the grep command's process then grep whoami will look for your currently logged in user then grep tomcat will look only for tomcat process, test it once and if All is Well then you could kill it.
By the way how about tomcat stop script? In case it is there you could use that also.

You can use shell variable $!. It represents the PID of the most recent background command.
yourCommand &
CMD_PID=$!
echo $CMD_PID

How to get PID and Port # for a Jenkins Process

I need to get PID & Port# for a Jenkins process run. If i get that PID, i can kill the process if ever i need to.
I am running the Jenkins process by below commands:
java -jar jenkins.war
Sometimes, Jenkins Process fail to start if that port is taken and below occurs:
Jenkins home directory: /Users/MacPro/.jenkins found at: $user.home/.jenkins
Feb 27, 2016 10:46:09 AM org.eclipse.jetty.util.log.JavaUtilLog warn
WARNING: FAILED
SelectChannelConnector#0.0.0.0:8080:java.net.BindException:
Address already in use
java.net.BindException: Address already in use
And I know how to run the jenkins process against a specific Port#.
Need to know the commands for which PID and the port, current job is using.

The command will be below:
ps -ef| grep jenkins
It will display the process id.

This should do the job. Better to find and kill using the same command, saves time:
ps -Af | grep "jenkins" | grep -v grep | awk '{print$2}' | xargs kill -9
You can check the process before killing
ps -Af | grep "jenkins" | grep -v grep | awk '{print$2}'
If you are running Jenkins using tomcat
ps -Af | grep "tomcat" | grep -v grep | awk '{print$2}' | xargs kill -9
Please note that these commands tested on RHEL.

Answer to your question
1) In Unix box, the command usage will be ps -ef| grep jenkins, it will display the process id (pid)
2) kill -9 (pid)

You could try the following command for a cleaner output:
lsof -Pni | grep mysql

how to stop all ports in apache tomcat

While developing a web application using Apache Tomacat and Eclipse frequently I get this message
Several ports (7354, 6544, 9999) required by Tomcat v7.0 Server at localhost are already in use. The server may already be running in another process, or a system process may be using the port. To start this server you will need to stop the other process or change the port number(s).
I know that this ports are in use, but I don't if I stop all those servers also why get the same message. My question is - Is there any way to stop all ports at once in using Eclipse or Windows 7 ?

you can use the lsof in combination with awk. do the following:
lsof -i :<portnumber> | awk '{print "kill -9 "$2}' | sh
if you want to know only the processId from the port, use:
lsof -i :<portnumber> | awk '{print $2}'
btw: i have this problem sometimes too. If you're using eclipse check in the debug view if there is still a thread of the tomcat running. if so, stop them :)
Otherwise restart eclipse.

Have you tried the following?
ps -ef | grep <port number>
kill -9 <process id>