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

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How to list killable tasks?

As manpage of ps states A process with STATUS with the value "D" means "uninterruptible sleep (usually IO)" Also, I've read: You should use TASK_INTERRUPTIBLE here, otherwise your kernel thread ...
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389 views

how to stop kernel threads preempting real time user space processes?

I created some processes in user space and tried to visualize its working in kernelshark with the trace recorded using trace-cmd. But kernel processes like the ones shown below are preempting my ...
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5answers
2k views

Get return value of process by PID

If I have the PID of a process that was killed, how might I get the return status of the process? I am particularly interested to know if the return status was 143 (kill) or 137 (kill -9) as I don't ...
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4answers
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How to send keystrokes (F5) from terminal to a process?

I'm using an Raspberry Pi in combination with Chromium (kiosk mode) to show up some stats. The Pi doesn't have an connected keyboard so I searched for a solution to send keystrokes from the terminal ...
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1answer
241 views

Is there a way to see which process invoked a shell script?

Is there a possibility so see from some unix log file what process have invoked a bash/ksh shell script or is this shell script invoked manually from command line? So is there some log file which ...
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1answer
690 views

Linux: How to check whether a process is slowed down by other running processes

I have one process running on a RHEL 6.3 machine. Somehow this is taking a longer processing time than the same process running on another machine. How is it possible to know why this process is ...
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2answers
128 views

Absolute path to currently-running zsh?

Sometimes the output of ps -p $$ shows the absolute path to the currently-running zsh, % ps -p $$ PID TTY TIME CMD 1027 ttys005 0:00.11 /usr/local/bin/zsh but not always: % ps -p ...
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5answers
983 views

Is there a way to listen to process?

I want to know if there is a way to listen to a process in linux & unix - when it ends and what's the exit code of the process(script). I dont want to write a script that will run X seconds and ...
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2answers
789 views

Does linux kill heavy and long running background processes after they reach some threshold?

If I start a really heavy (memory/cpu intensive) running really long running process will the OS terminate it after a period of time arbitrarily? I.e. are there any limits beyond which the OS would ...
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3answers
26k views

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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2answers
885 views

a handy tool to measure memory consumption of a program [duplicate]

I develop a C code on Debian. I am looking for a program to monitor memory consumption of my code in real-time. The only value I care is the maximum RAM consumption, it should hold the value even if ...
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1answer
23k views

How to see process created by specific user in Unix/linux

I want to see list of process created by specific user or group of user in Linux Can I do it using ps command or is there any other command to achieve this?
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0answers
99 views

Linux child processes not being culled [closed]

This is causing significant problems for script portability between BSD and Linux. I am on a CentOS 6.4 where this happens. I have a nice compact test case: bash -c "inotifywait -mcr . | sed ...
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3answers
3k views

How can I check what signals a process is listening to?

How can I verify whether a running process will catch a signal, or ignore it, or block it? Ideally I'd like to see a list of signals, or at least not have to actually send the signal to check.
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0answers
373 views

gnome-terminal cmd leaving processes open after closing parent window

The following simple command should demonstrate my issue: gnome-terminal --tab -t "Tab 1" -e "/bin/bash" --tab -t "Tab 2" -e "/bin/bash" This should open a new window with two tabs and an active ...
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2answers
956 views

How to kill a script which starts new processes?

The following is a Python application which spans a few threads, then spawns a new process of itself and exits: $ cat restart.py import os import random import signal import sys import threading ...
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3answers
1k views

How can I start a process using cpulimit?

I am trying to use cpulimit for testing an app I'm developing under low resource conditions, and I need the process to start under the influence of cpulimit. It is not sufficient to start the program ...
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2answers
504 views

what is an application pool?

I'm reading this article: http://www.modrails.com/documentation/Architectural%20overview.html#web_app_models It talks about how Phusion Passenger extends Apache2 to act as an application server. ...
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2answers
463 views

When vfork is called is parent process really suspended?

As much as I know when vfork is called child process uses the same address space as that of the parent and any changes made by the child process in parents variables are reflected onto parents ...
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3answers
331 views

How do I know if acct is running? (The Unix system accounting)

I have installed the acct package and it is running because I can see file activity in the log file. I know there is the command accton on to turn it on, but how do I determine that its running short ...
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1answer
116 views

What is meant by “a process has open handles to system objects”? [closed]

The following are qualities of a process: virtual address space executable code open handles to system objects a security context a unique process identifier environment variables a priority class ...
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4answers
1k views

Process is eating all of the CPU time

Is there any magic command to track down which process is starting this perl task that is eating 100% of CPU time? I have this problem on several machines where JBoss AS is installed.
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3answers
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Which process has PID 0?

I'm looking for the process started in Linux which has process ID 0. I know init has PID 1 , which is the first process in Linux, is there any process with PID 0?
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3answers
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Contents of stack area of a process

I've been going through some Unix text books and I can't have a clear picture on the contents of the stack area of the process. Can anyone please explain or point out some references?
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2answers
297 views

Bash operator & not working [closed]

As per the bash reference, we can give a non-blocking command by ending it with an ampersand(&) character. However, when I try the below command its not working: python -m SimpleHTTPServer ...
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2answers
362 views

Current environmental variables of a process

This question relates to this answer. Is it possible to get the current (not initial) environmental variables of a process by making a child process and checking its initial environmental variables? ...
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4answers
644 views

How to get the id of a very short child process if the parent is known?

I'm looking for a way to get the PID of a short child process in Linux. The process is instant from a human perspective. I know the parent process which will spawn the child process. Is there a way ...
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2answers
263 views

How to get environmental variables of a very short process?

I have a very short process for which i want to check the environmental variables for debugging purposes. The process is instant from a human perspective. The example illustrates it better. Example ...
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2answers
739 views

what is a background process?

Here is a common definition of a background process: "A background process is a program that is running without user input. A number of background processes can be running on a multitasking operating ...
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3answers
4k views

Possible to get SMS/text message notification when process ends/is killed?

There are scripts that will send an e-mail when a server process is finished. However, I do not want to check my email every so often just to see whether a job has finished. Therefore I'd like to get ...
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1answer
107 views

Find if a process terminates in a specific amount of time

I am running a program.Inside this program i run a specific command and i use ulimit command to terminate the running of that command if it exceeds an amount of time.To be more clear i run this: ...
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1answer
370 views

pmap and memory usage

On Ubuntu 12.04, I have several apache2 processes running (the 1130 parent and the children it spawned), and as you can see, they have around 300-400 mb of virtual memory and 10 mb of resident memory: ...
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2answers
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ps switches to display PID, PPID, PGID, and SID collectively

I tried ps with different kinds of switches e.g. -A, aux, ef, and so forth but I cannot seem to find the right combination of switches that will tell me the Process ID (PID), Parent Process ID (PPID), ...
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2answers
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Zombie process cannot be removed or killed [duplicate]

I have a zombie process that refuses to be removed, have tried killall -9 1913 and pkill with no effect. Any help would be very much appreciated.Running Ubuntu 12.04.2 LTS. Thank you. ...
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96 views

Are zombie processes something I should be concerned about? [duplicate]

I run a server. Should I be concerned about zombie processes? Do they consume any system resources (RAM, process table entry, etc.) that I should be concerned about?
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1answer
94 views

Run a script when a process throws stderr message

I want to "wrap" a process around another to catch stderr messages when they occur. Use Case I'm using Compass and I have to have a terminal open and see if there is something wrong. My plan is to ...
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1answer
300 views

Deadlock in a crontab between cron and its child defunct processes

I'm having a strange case of deadlock, where the two processes launched by cron are defunct, but cron does not pick the return code and exit. I don't have access to the root user. myuser@myserver:~) ...
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4answers
14k views

How to kill a process which can't be killed without rebooting?

There are 5 processes which can't be killed by kill -9 $PID and executing cat /proc/$PID/cmdline will hang the current session. Maybe they're zombie processes. Executing ps -ef or htop will also hang ...
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2answers
1k views

“ps” command doesn't return to prompt

I have this linux box that I need to maintain periodically. To do that, I issue a ps command programmatically and check the running processes. But as shown in the screenshot, sometimes, the ps ...
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1answer
1k views

what is the structure of a linux process? [closed]

what is the structure of a linux process? In linux there are processes executed on a address and which use system resources. Can anyone tell me the structure of a process and which parameter ...
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1answer
372 views

init: is it a user thread or a kernel thread?

init is the first task executed after kernel is loaded, right? Then who is its owner. also I can see [swapper/0] [swapper/1] ..... [swapper/7] having pid 0 PID PPID CPU TASK ST %MEM ...
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3answers
2k views

Determining the particular processor on which a process is running

I have access to an 8-core node of a Linux cluster. When logged in to the node, I can see a list of processors using this command: more /proc/cpuinfo In my 8-core node, the processors are numbered ...
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3answers
18k views

Terminating a bash shell script running in the background

I often use bash shell scripts to run simple commands for many different files. For example, suppose that I have the following bash shell script, called script.sh, that runs the program/command foo ...
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1answer
698 views

How does One Find the PID of a Process Started with startproc?

My understanding is that it's generally a good idea to create a PID file for daemon processes and that startproc is a good way to start these daemons. I know that startproc takes -i and -p arguments ...
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9answers
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Bash way to check if a process is already running in the background (and skip re-execution based on that)?

Can I make a bash command line that only runs a certain command if the process is not already running (in the background)? How do I check*, if a command is already running? (so I can add the next ...
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3answers
19k 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 ...
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6answers
5k views

Can ps display only non kernel processes on Linux?

How can I ask ps to display only user processes and not kernel threads? See this question to see what I mean...
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4answers
583 views

Best practices for job/process tracking and multi-tasking

I run 10+ different commands from 10+ different directories, and I need a better process to track everything. I do a lot of debugging, and often times I need to work on multiple issues in parallel. I ...
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1answer
357 views

AIX why does ps display the process name between square brackets? [duplicate]

On AIX 7 I have a process whose name appears between square brackets in the ps output: PID TTY TIME CMD 7798784 pts/2 0:00 [myproc] 9044154 pts/2 0:00 ps 10485770 pts/2 0:00 ...
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3answers
124 views

How to know if a specific program is open

Using a command line in terminal, I want to be displayed 1 if a program (for example Firefox or Chromium) is open and 0 otherwise. Edit: By "open", I mean "is running on the current machine and has a ...