Questions tagged [process]

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

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Process with dynamic id won't kill; has no parent

I am trying to kill process like this: root@xxx:~# ps -ef | grep mosquitto root 3083 1912 0 11:59 pts/0 00:00:00 grep --color=auto mosquitto root@xxx:~# kill 3083 -bash: kill: (3083) - ...
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Load a core dump continue running

I can create a coredump as a snapshot of a process's image and continue running. Can I then, on another run of the program load the coredump and continue at that same point in time? If so how? ...
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How to assign process to work on partial CPU's? [duplicate]

We want to run our applications ( process ) only on the first 6 CPUs. We have a RHEL machine. We have physical DELL machine with total 12 cores (from lscpu) Is it possible to assign the process to ...
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Restart a process if a message is detected on stdout

Is there a way of monitoring a process (like for example with supervisord), and then restarting the process if the stdout outputs a specific line of text? In my case the line to check for would be: ...
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Rationale for restrictions on setpgid() call?

I was reading Chap 34 (Section 34.2) of the book Linux Programming interface, when I came across the following restriction while making use of setpgid() call. The pid argument may not specify a ...
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1answer
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Give user permission to change priority of an IRQ/root process

Is it possible, in Linux, to allow an user to change the priority of a process owned by root? More specifically an IRQ process? For an embedded real-time application I want to raise the priority of ...
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1answer
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Sort ps output by the command in Solaris

The purpose of this exercise is to dump the output of ps sorted by command. While the system is running we wish to dump all the running process sorted by command in a file. There is a sort option in ...
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1answer
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Extracting $! from multiple process substitutions

Consider the following: exec > >(tee -a mylog) 2> >(tee -a mylog >&2) pspid=$! Which tee process has the pid of $! above? If we want the pid's of each tee processes above how do we ...
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Redirection inside background process

Consider the following code: exec > >(tee mylog.stdout) 2> >(tee mylog.stderr >&2) # ^^^ # why do we need this >&2 ? If removed,...
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The parameters a new process inherits

It appears that a new Linux process inherits its parent's present working directory, umask, process group (getpgid) and process session (getsid). Also, the parent's PID becomes the new process's ...
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Closing stdout required for wait on sub process to finish?

I have a question from https://mywiki.wooledge.org/BashFAQ/106 Have a look at this code: exec > >(tee myfile) pspid=$! # ... stuff ... echo "A" cat file echo "B" # end stuff ...
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Is releasing memory pages by a process possible in principle?

Disclaimer: I do have a diploma in CS but this topic was never explicitly explained to me. I am just stiching pieces of what I know into a whole. Please correct me if I get something wrong. Suppose ...
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Why is my host displaying 2 cron processes?

I notice that I am getting 2 different cron processes in ps: [user@host ~]$ ps aux | grep -i cron 500 746 0.0 0.0 6384 676 pts/1 S+ 13:40 0:00 grep -i cron root 905 0.0 0.0 ...
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2 of the same processes with different PIDs running - not threaded

This is not a multi-threaded process. With ps and top I observed: [user@host]$ ps aux | grep -i [r]redacted ...
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Process substitution under the hood

This question is from https://mywiki.wooledge.org/ProcessSubstitution mkfifo /var/tmp/fifo1 mkfifo /var/tmp/fifo2 sort list1 >/var/tmp/fifo1 & sort list2 >/var/tmp/fifo2 & diff /var/tmp/...
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How to check for active ssh port forwarding connections on MacOS

On my local MACOS I setup a reverse ssh tunnel using the below command. ssh -fnN -R 2222:localhost:22 remoteuser@remotelinuxhost And then my MACOS is controlled by the remote linux host which fires ...
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High program load, when killed program process, Linux doesn't go back to 0.5 normal load. Why?

I ran a program that reached CPU load of 39.99, obviously more than my 4 core CPU can handle but why when I killed the program, (which is killed), the CPU load doesn't drop to 0.50 when I didn't turn ...
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1answer
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PID of background function “$!” gives wrong value

I am trying to capture the PID of a function executed in the background, but I seem to get the wrong number. See the following script: $ cat test1.sh #!/bin/bash set -x child() { echo "...
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How can I control a shell script from outside while it is sleeping?

I am fairly new to shell scripting. I have a script similar to the following, while [ true ] do sleep 5m # PART X: code that executes every 5 mins done While this is running (1) how can I ...
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1answer
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Mystery of Zoom auto-restarting, how do I stop it?

I'm running an ordinary Debian system on which I have installed Zoom. After using Zoom, and quitting, the program keeps restarting. After I kill it I use ps to check and it is gone, after about 15 ...
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SystemD error: opendmarc.service: Can't open PID file

Mail server: Ubuntu 18.04, Postfix, Dovecot, spf + dkim, opendmarc Problem: Opendmarc starts and works as expected but still persistent message: Can't open PID file /run/opendmarc/opendmarc.pid (yet?) ...
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Is it just me or is the man page for renice ambiguous?

I am considering renicing some processes so that they will remain responsive under heavy load on a server. I read the short man page for renice, and I understand it less each time I re-read it. It ...
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Varnish duplicate process 170 once

I am using nginx + varnish. I noticed that I have ~ 22GB / 32GB in use. I looked in htop and noticed that there are about 170 duplicate varnish processes. Tell me what could be the problem? Where to ...
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Alibaba Cloud Monitor agent VS top command. Who should I trust?

Alibaba agent says the system CPU is hitting over 90% But when I login to the system and check CPU with top command, it says it's around 60%. This repeatedly happens but I don't know which one to ...
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Can we collect Statistic about how many times an Appliction is minimized or maximized in Linux?

Is there anyway which provides user, statistics such as, how many times an Application window was minimized, or maximized. Lets say how many time a browser was minimized or how many times it was ...
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How do I automatically close the process left behind by a misbehaving application after it exits?

There are applications that do not exit cleanly leaving behind their process. One example I've found is Foxit Reader. Of course, the ideal would be to report a bug and have the application fixed, but ...
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Kill process if it takes more than xGiB of RAM in a given amount of time

I am a software developer and I come into contact with a lot of unstable software. Recently I made a small game, which for some reason memleaks until the system hangs and is unresponsive. Usually, ...
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Problem in understanding how the operating system and memory works in a Unix system [closed]

I am an undergraduate mathematics student and I am currently doing a course in operating system with a very little background in computer science. Here are the basics that I know - An operating system ...
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Find what process making outgoing connection on port 80

We are stuck in identifying which process or service that we are running in our linux machine is making a connection to a remote IP. We are getting complaints of our network accessing the remote IP ...
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Why Bash Parent Process exits before its child when command is used in background in a Bash script?

Let's say I have for the following simple bash script: test_bg.sh #!/bin/bash ping www.google.ro &> /dev/null & If I execute it directly via ./test_bg.sh and do a ps -ef after, I see that ...
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1answer
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Getting the executable name in Linux from /proc/ and detect if it's truncated

The executable name is linux can be read in various ways. By reading /proc/[pid]/comm, which contains a string that's truncated after reaching 16 characters or TASK_COMM_LEN. By reading /proc/[pid]/...
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Why is the command sleep an independent process but others seemingly not when used in a shell script?

I'm writing a bash script named test.sh as below on my Ubuntu: #!/bin/bash while true; do echo 'abc' # pwd, df... sleep 1 done When I execute ./test.sh at one terminal, I open another ...
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how to check running process on cpanel terminal?

I run a python scrapper on cpanel terminal, but after log in again and check the terminal it was not showing the process running. how can i check if it is still active or i need to run again. i just ...
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1answer
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Does a program run by bash runs in a new job?

In this video, it is said that: In the normal arrangement, if you open a terminal, and inside you have a shell running, that shell represents the start of a new session. That session starts with one ...
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Why is pgrep/pkill so much slower than ps?

I would have thought that pgrep would be much faster than ps -ef yet the contrary is true - pgrep takes about 4x longer. But only on my laptop e.g.: $ time { ps -ef |grep foobar; } real 0m0.027s ...
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1answer
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Is data retained in memory if there is a network disconnect? If so, how can I see that data?

I am trying to see if data is retained in memory if there is a network disconnect from a system shut down on Machine 3. All machines are running RHEL 7. My setup is as follows: Machine 1 > ...
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1answer
41 views

Is it possible to modify an executable which is already running?

I have a Linux system which is running in an embedded system. For various reasons I can't get into (or I'll get fired), I don't have direct access to this system through normal means like a keyboard, ...
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1answer
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How do I get all the stats about a specified pid? E.g. how long it ran? max/min/avg usage of cpu, memory, disk and network?

Here is a tiny C++ app #include <iostream> #include <unistd.h> using namespace std; int main() { cout<<"Hello World"<<endl; std::cout << "pid = &...
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Virtual Address Space [closed]

I have started to learn about Virtual Address Space (VAS) and I have few questions: How much of VAS is created for each process depending on the architecture (32-bit and 64-bit)? Is VAS for each ...
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1answer
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Linux cgroups: task vs pid?

What is the difference between a task and a pid? Inside of the /sys/fs/cgroup there a file called tasks which lists just pids, $ ls /sys/fs/cgroup/*/tasks /sys/fs/cgroup/blkio/tasks /sys/fs/...
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figure read speed access to a file from a process

Background info for the request:: I have a radius server (freeradius running on Linux) that for each request needs to parse a long text file containing the allowed mac-address. From time to time, it ...
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2answers
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Is it possible to check the process id of child in different pid namespace?

Is it possible to find the PID of the child process which is in a separate PID namespace? I am able to get the child process PID with respect to the parent namespace but I need to find the PID of the ...
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1answer
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How to spawn each child process in separate pid namespace

How to spawn each child in a separate PID namespace using unshare (without CLONE_NEWPID flag in child process clone syscall). I am able to successfully spawn first child in PID namespace but I am not ...
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How GUI applications receive keyboard input?

I started Firefox from by bash window by entering the command "firefox", it started the Firefox browser in the user interface. When I checked the Firefox process by entering "ps" ...
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How to kill a command run from a script after a period? [duplicate]

I would like to run a never-ending command (such as play a mp3 file in loop) for a period of length T. I put the command in a shell script my.sh: #! /bin/bash vlc /path/to/my.mp3 # will play the file ...
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Launching a program via `xdg-open` from a subshell without blocking

I've noticed that calling xdg-open from a subshell will reliably block until the launched process is closed. I suspect there may be a reason for this, but I'm not sure as to why. For example, ...
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killall and kill doesnt work

I scanned using ClamAV and found these files: [root@ip-172-31-23-37 ~]# sudo clamscan --infected --recursive --exclude-dir="^/sys" / /tmp/.X25-unix/dota3.tar.gz: Multios.Coinminer.Miner-...
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How to find out which process access outgoing ssh?

My EC2 instance reported got suspicious activity and I got this email: has been implicated in activity which resembles scanning remote hosts on the internet for security vulnerabilities. Activity of ...
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1answer
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Is a process in TASK_INTERRUPTIBLE state waken up only by the delivery of a signal?

The Linux Programming Interface says 22.3 Interruptible and Uninterruptible Process Sleep States We need to add a proviso to our earlier statement that SIGKILL and SIGSTOP always act immediately ...
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1answer
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TTY = ?, How input is read

When listed down the running processes, I can see several processes like 'chrome', 'notepad', 'intellij', 'sublime editor' etc.. are having "tty = ?" Then how are they able to read the ...

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