A process is an instance of a computer program that is being executed.

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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 ...
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Why is SIGINT not propagated to childs process when sent to it's parent process?

Given a shell process (e.g. sh) and it's child process (e.g. cat), how to simulate the behavior of CTRL+C using the shell's process ID? This is what I've tried: Running sh and then cat: ...
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Why does the location of Enviroment Variables vary that much?

Reading the book Hacking: The Art of Exploitation by Jon Erickson, I am trying to approximate the address of an environment variable SHELLCODE to exploit a program. Every time I run ...
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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 ...
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Need explanation on Resident Set Size/Virtual Size

I found that pidstat would be a good tool to monitor processes. I want to calculate the average memory usage of a particular process. Here is an example output: 02:34:36 PM PID minflt/s ...
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271 views

How can I track executables created by my user on Linux?

Using Linux, I would like to track the executables that are executed in my name, including the whole command line (in practice, every exec*() done as my own user). A program I do not control is ...
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183 views

Print pids and names of processes as they are created

From the question here, the OP wants to repeatedly poll the pid of a process using pidof in a shell script. Of course this is inefficient as a new process must be started for the pidof program ...
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Elegantly get list of descendant processes

I would like to get a list of all the processes that descend (e.g. children, grand-children, etc) from $pid. This is the simplest way I've come up with: pstree -p $pid | tr "\n" " " |sed "s/[^0-9]/ ...
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706 views

Negatives of running processes with real-time priority?

The question is as the title says, are there any downsides of running processes with real-time priority (chrt -f 99)? My hypothesis is that this combined with an affinity will ensure that any ...
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670 views

Why does “kill -9 0” end my console session?

I just wonder why kill -9 0 ends my tty console session? What exactly is PID 0, it is not listed on a ps aux?
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Suspend/resume single process to/from disk

On occasion, we would like to suspend memory-intensive processes on our Ubuntu and OS X servers to temporarily free up some RAM for other jobs. If all we were worried about was CPU usage, a simple ...
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Launch process as another user/group (in init.d script)

I am editing a init.d script. The init.d script runs a utility script which then runs an process. From either bash scripts how would I make it launch the main process as a specific user and group?
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Nice and child processes

Can someone tell me what the relationship between a specified nice level and child processes ? for example, if I have a default nice of 0, and i start a script with nice 5, which in turn starts some ...
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How can I tell when a process has finished writing to a file?

I have a process which has been spawned from a shell. It is running as a background process and exporting a DB to a CSV file in /tmp. How can I tell when the background process has completed ...
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914 views

how to find out namespace of a particular process?

I already asked a question about how to list all namespaces in Linux, but there wasn't any correct and exact answers, so I want to find out a method which can help me to find out the namespace of PID ...
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384 views

How can I create a hard to kill process

I want to create a program that will be difficult to stop (even for the administrator) once it is started (with root privileges). Once started the process should continue to start itself at startup ...
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How to kill both process and subprocess?

I asked a question to know how to get multiple lines of message from Python's subprocess module. The problem is that in the course of testing, I had to kill the python process that runs gnuchess ...
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Understanding top and load average

I'm observing a high load average on a certain machine (about 9) in all three load fields. I understand load as the number of processes in state "run" / currently desiring CPU time. Am I correct at ...
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429 views

Reliable way to jail child processes using `nsenter:`

I know that Linux namespaces, among many other things, can be leveraged to handle restricting and jailing child processes securely without any chance of their being zombied and dumped on init. But I'm ...
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How to check, which limit was exceeded? (Process terminated because of ulimit. )

Let's assume process runs in ulimited environment : ( ulimit ... -v ... -t ... -x 0 ... ./program ) Program is terminated. There might be many reasons : memory/time/file limit exceeded ; just ...
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635 views

How to find source of spawning process?

I have a Java process running on a RedHat Linux instance. The problem is it keeps reappearing after I kill it. I am not sure where to look. I've already went to crontab, but no luck. I've looked at ...
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Use & (ampersand) in single line bash loop

I have been using this command successfully, which changes a variable in a config file then executes a Python script within a loop: for((i=114;i<=255;i+=1)); do echo $i > numbers.txt;python ...
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How do I know what service is running on a particular port in linux?

I am trying to run weblogic server on my linux machine and I am getting the following error : ERROR: transport error 202: bind failed: Address already in use ERROR: JDWP Transport dt_socket failed to ...
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Are kernel threads really kernel processes?

I've read in many places that Linux creates a kernel thread for each user thread in a Java VM. (I see the term "kernel thread" used in two different ways: a thread created to do core OS work and a ...
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nohup vs. Screen

In the past, I've used nohup to run big background jobs, but I've noticed that a lot of people use Screen in this context. Does Screen provide some kind of functional advantage that I am unaware of, ...
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How to stop xargs from badly merging output from multiple processes?

I'm using xargs with the option --max-args=0 (alternatively -P 0). However, the output of the processes is merged into the stdout stream without regard for proper line separation. So I'll often end ...
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How to list processes locking file?

Using flock, several processes can have a shared lock at the same time, or be waiting to acquire a write lock. How do I get a list of these processes? That is, for a given file X, ideally to find the ...
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597 views

Harddrive I/O per Pid

is there any way to see the disk I/O per pid/process ? Monitorix shows me the following and correct me if I´m wrong, but it looks like that the harddrive is slowing down the whole system: UPDATE #1 ...
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If I see a process running using ps, how can I find the executable?

If I can see a process running using ps -e, how can I find the file which launched it?
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Execute Nohup command with input

In UNIX, I have a process that I want to run using nohup. However this process will at some point wait at a prompt where I have to enter yes or no for it to continue. So far, in UNIX I have been doing ...
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Why Process/program becomes zombie?

If script is running fine from command line then, why the same script becomes zombie state after running through cron and How you will troubleshoot the same ? Here following real example : [root@abc ...
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How to stop a bunch of processes on unix fast?

How to stop a bunch of processes on unix fast. I can use ps/top, kill. If the number of processes is very large, I use shell script. Are there other ways, only one or two unix commands can do it ...
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739 views

Finding out with which parameters a program was started

Is there a way to find out for any given process with which parameters it was started?
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What's the purpose of the /proc/pid/mountinfo file?

What's the purpose of the /proc/pid/mountinfo file (with pid being numerical process id)? As far as I can see it reflects contents of the /proc/mounts file but with added information. Also the file ...
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Simulate an unkillable process in D state

For catastrophe testing scenarios on out server environment we're looking for an easy way to make a process stuck in D (uninterruptible sleep) state. Any easy ways? An example C sample code would be ...
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Why is I/O uninterruptible?

What is the rationale behind making I/O uninterruptible? What would be the negative consequences if a process handling I/O were allowed to handle a signal?
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How to kill a daemon with its name gracefully?

I usually kill a process with killall. killall markdoc But I am not sure if this command terminates the process gracefully. Does this command achieve graceful termination? If it does not, how can ...
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Process descendants

I'm trying to build a process container. The container will trigger other programs. For example - a bash script that launches running background tasks with '&' usage. The important feature I'm ...
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632 views

How to find tty from which a particular cmd “scp” is executed

How can I find out who executed a particular command and which terminal was used to run it? Original: how can i know particular cmd is executed by whom and to know about my terminal
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Real time priorities in non real time OS

If I do the following command on my standard Linux Mint installation: comp ~ $ ps -eo rtprio,nice,cmd RTPRIO NI CMD ... 99 - [migration/0] 99 - [watchdog/0] 99 - [migration/1] - 0 ...
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Is the sum of all PIDs “utime” the total system utime?

In order to measure a user's total CPU time, I'm using the "utime" field out of /proc/[pid]/stat: utime %lu Amount of time that this process has been scheduled in user mode, measured in ...
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Silently start task in background

I know that you can use this to start a process in the background, without getting the notification when the process is put in the background and when it is done like so: (command &) &> /dev/null ...
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How can you determine which process scheduler is being used? [duplicate]

I.e. is it the O(1) scheduler, the CFS scheduler, or an older one?
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311 views

What should interactive shells do in orphaned process groups?

(Re-posting in unix per the suggestion in http://stackoverflow.com/questions/13718394/what-should-interactive-shells-do-in-orphaned-process-groups) The short question is, what should a shell do if it ...
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Kill user processess on logout

I have a Ubuntu server that handles remote X sessions from users. However, I don't want to allow users to run any kind of background processes - so here is my question: How do I prevent users from ...
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Running continuous jobs remotely

I'm new to Linux, and I'm probably asking a fairly basic question. How do I run a continuous program on Linux? Basically, I have a program that will continuously check for content on a website. This ...
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423 views

Understanding environmental variables in different contexts

Trying to understand the behaviour of the environment in Linux (Ubuntu 13.04 concretely), I've find different situations where setting envirionment variables are used or defined for/in different ...
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How is /proc/self implemented in Linux?

I was tinkering around with the /proc filesystem in Linux, and I came across /proc/self, which is a symbolic link to the process directory of the current process. I would like to know how it is ...
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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 . ...
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killall gives me `no process found ` but ps

Could somebody explain to me the difference between kill and killall? Why doesn't killall see what ps shows? # ps aux |grep db2 root 1123 0.0 0.8 841300 33956 pts/1 Sl 11:48 0:00 ...