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

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Write inside a socket open by another process in Linux

Is it possible on Linux for a process to write inside a socket open by another one? Let's say I open a connection to google.com using netcat: myuser@linux:~$ nc google.com 80 Now I can lookup for ...
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641 views

Is there a way to identify which process turns into Zombie process

One of the ubuntu server has 82 zombie processes. All processes shows '[sh] defunct' as process command. Is there a way to find out which process is becoming a zombie process? I tried checking the ...
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1answer
89 views

Command to list in real time all the actions of a process

I cannot remember this command (and googling was unsuccessful), but there is a way to get the list of actions performed by a process, that outputs something like # listprocessactions -p 1234 ...
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Getting information about a process' memory usage from /proc/pid/smaps

For a given process in /proc/<pid>/smaps, for a given mapping entry what are: Shared_Clean Shared_Dirty Private_Clean Private_Dirty Is Shared_Clean + Shared_Dirty the amount of memory that ...
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Graceful way to kill process

After my bash script is done with the selenium server, the script kills it like this: kill `ps -ef | grep selenium | awk '{ print $2 }'` While this works and it does kill the selenium script, it ...
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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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1answer
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How can I send data to the STDIN of a background process?

I'm trying to: Launch several ssh sessions (processes) through a script (Python) Communicate with the sessions by sending them commands via STDIN (even though they aren't open in my current ...
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Apache cannot fork: cannot allocate memory

I am running apache on Fedora with mod_perl. The server forks a process to send an email frequently - and the fork exits. Suddenly, I got: Cannot fork: Cannot allocate memory. There was plenty of ...
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How to stop a program running as daemon

I have launched iperf in daemon mode with iperf -s -D and now I want to stop the service. I tried to use sudo kill pid but it neither work nor complain. The daemon is still running when I check ...
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How to attach terminal to detached process?

I have detached a process from my terminal, like this: $ process & That terminal is now long closed, but process is still running and I want to send some commands to that process's stdin. Is ...
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1answer
547 views

Cross-platform (Linux, BSD, Solaris) way to check if pid exists

I am looking for a reliable cross-platform way to check if a process with a specific pid is running. Two possible solutions came up: kill -0 $PID — exit status is 0 if it the process exists and 1 ...
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2answers
702 views

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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How does forking affect a process's memory layout?

Please see the following figure showing the memory layout of a process: : When someone forks(), and a new task_struct is assigned, what happens to the addresses of the process? In more or less other ...
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Why is my C++ program killed by OS

I've compiled small C++ application for school project on my virtual ubuntu 11.04. However when I attempt to run it over some larger data set after ~20 sec the program is killed by OS. Killed ...
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Why is the default process creation mechanism fork?

The UNIX system call for process creation, fork(), creates a child process by copying the parent process. My understanding is that this is almost always followed by a call to exec() to replace the ...
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1answer
269 views

Unkillable apache2 processes

After upgrading from debian lenny to squeeze (apache2 2.2.16-6+squeeze4 and php 5.3.10-1~dotdeb.1), my apache processes started to exit with segmentation fault. It happens every 5-30 minutes (for 1 ...
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3answers
574 views

Maintain 100 instances of a program running

I'm currently using supervisord to maintain 100 instances of a script running at once. If any die then it starts up a new one. However it seems to be struggling maintaining larger numbers (>300 ...
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162 views

Detecting whether a server is loaded

I have to start some performance test on a Rhel 6 box, but before starting the test, i have to make sure there are no other java processes running. The manual way of doing it would be to use "ps -ef ...
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1answer
540 views

How can I manage jobs after I disconnect from my tty/ssh session?

If I ssh to a box and start a task that will take some time to complete I usually press control+z to pause the process, and then immediately type bg 1 to put run it in the background. I can then type ...
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How to read environment variables of a process

Linux's /proc/<pid>/environ does not update (as I understand it, the file contain the initial environment of the process). How can I read a process's current environment?
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killing processes automatically

I need to kill all processs in a certain shell excluding certain processes. Like sh which is my shell. And the comand. This is what currently in my shell right now. rcihp146 :/home/msingh2> ps ...
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2answers
570 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 ...
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1answer
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Is it the process that cleans itself on termination or the kernel?

Recently I found this in a powerpoint presentation: When a program is compiled and linked, the linker inserts some extra code in the program. It is this code that calls the main function about the ...
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What is meant with terminating a process normally?

In an examination it is stated: Give 2 different ways that a process can terminate normally. Describe the differences. What is meant with terminate normally?
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How to kill a daemon with its name gracefully?

I usually kill a process with killall. killall markdoc But I can't sure this command terminates the process gracefully. Does this command graceful termination? If it's not, how can I kill a ...
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Is it possible that a method inside a module (in kernel mode) be preempted?

My basic question is about system stack of a thread, and system stack of a process Two methods in a module? Which of the methods can be preempted via kernel mode preemption, the one in process ...
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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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1answer
233 views

Why is the following command killing a system?

Anyone understand the following code , running in bash ? :(){ :|:& };: It seems to be a "fork" bomb on Linux.
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1answer
139 views

Alert when a process exits

I often download files using wget and cURL. Is there anyway I can make my Linux box give a visual alert when either of those processes exit (i.e: the download completes) PS : I am using Ubuntu ...
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5answers
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How to get a process uptime under different OS?

Under Linux I can get a process's uptime in seconds with: echo $(($(cut -d "." -f1 /proc/uptime) - $(($(cut -d " " -f22 /proc/$PID/stat)/100)))) But how can I get it under different OS? ex.: ...
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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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1answer
959 views

Limit process resource consumption in CentOS 5 (2.6.18 kernel)

I would like to limit the resource (CPU, Memory, and network bandwidth) consumption of processes on the same server. And it will be good if I can migrate processes from one server to another. I ...
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Will process ids be recycled? What if you reach the maximal id?

Process IDs are strictly increasing, but if your system runs long enough and there is a lot of processes terminating and starting, you could at some point reach the limit of the underlying integral ...
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Why is apache2 showing up a defunct in the process list?

When I run top I see one line that doesn't look too good: 2475 www-data 20 0 0 0 0 Z 1 0.0 0:00.19 apache2 <defunct> Why is this process <defunct> and what should I ...
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494 views

Why does my one instance of VLC have many processes?

As you can see from the image below (htop), I have several vlc processes running, all with only the command vlc. However, I'm only running one vlc instance. What are the other instances? Would it ...
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2answers
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killing a process on a remote machine when the machine is stuck

I started a very resources-consuming process on a remote server via ssh. It is an optimization problem run in MATLAB. It takes full memory and CPU. In fact, I am not even able to ssh to the machine, ...
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1answer
439 views

Enter process running in background/bring to foreground [duplicate]

Possible Duplicate: How can I disown it a running process and associate it to a new screen shell? I started a java client using nohup to get it to run in the background (needed to log out ...
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Rogue Java process brings my computer to a halt

In reference to my earlier post: Is there a log of past threads that are now closed? I gave the process a kill -STOP signal and started examining the details. I can't seem to figure out why it is ...
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2answers
353 views

Is there a log of past threads that are now closed?

Sometimes, I have a rogue Java process which takes up 100% of my CPU and makes it jump about 30C in temperature (usually resulting in a crash if not killed). Problem is, I can never really identify ...
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What is the lowest level I can see my system running?

Let me try and clarify. Is there any way for me to see very very low level activity on my computer? Stuff like: register content opcodes being sent specific memory addresses Or anything lower ...
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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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350 views

add “check if fetchmail is running” to this script

while ! postqueue -p | grep -q empty; do sleep 1 done killall wvdial this script checks if my mail queue is empty, then disconnects my modem. now i would like to add also a checking to fetchmail ...
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How to pkill by “command name”?

So I'm executing a command like: COMMANDNAME -PARAMETERS But..why can't I kill it with "pkill"? I'm trying with: pkill -9 "COMMANDNAME -PARAMETERS" but it doesn't kills the "COMMANDNAME ...
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3answers
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What is a subshell (in the context of the documentation of make)?

I'm reading a book about the make command and there is a paragraph: If any of the prerequisites has an associated rule, make attempts to update those first. Next, the target file is considered. ...
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how to disallow user to change process group

Is it possible to restrict a process from changing it's process group? For example, user nobody seems to be able to call setpgid(0, 0) which sets process group of current process to pid of that ...
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3answers
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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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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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How is FireFox running on a virtual machine that has no display?

I am using a Red Hat virtual machine, accessible only remotely. However when I use the top command, one of the displayed processes taking up the most memory is firefox, located at ...
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There is no bash indicator prompt after a forked process terminates

I am reading the book Advanced Programming in the Unix Environment. There is a test program to test the fork function. It works well in my Ubuntu. But what I confused is that why there is no command ...
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Limit process to one cpu core

How to limit process to one cpu core ? Something similar to ulimit or cpulimit would be nice. (Just to ensure: I do NOT want to limit percentage usage or time of execution. I want to force app (with ...