Questions tagged [process]

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

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How to get disk I/O activity by files and processes?

On Red Hat 8 I sometimes get huge disk I/O operations. I can see disk I/O activities by using sudo iotop -oP command. Output is: PID | USER | DISK READ | DISK WRITE ---- ------ ----------- ----------- ...
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How is a signal "delivered" in Linux?

I am confused by the terminology used to describe Linux signal delivery. Most texts say things like "the signal is delivered to the process" or "the signal is delivered to the thread&...
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Is it safe to kill the /usr/libexec processes?

I am running Ubuntu 22.04 and the laptop fans are not happy. I am just running 1 firefox window with YouTube in 1 tab, and a couple static pages in the others. No other applications are running. Specs ...
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1 answer
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Set affinity of a process using TASKSET or sched_setaffinity() to a processor core isolated using CPUSET

First, let me give a background of what I am trying to achieve. I know how to isolate a particular CPU using boot param (isolcpu and nohz_full; the housekeeping subsystem setup). But as per my ...
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rcu_sched vs rcu_preempt CPU stalls

I have basic query regarding the RCU CPU stalls, sometimes there is message like INFO: rcu_sched self-detected stall on CPU, and sometimes it's INFO: rcu_preempt detected stall on CPUs/task, what is ...
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How does linux prevent whole system from freezing when a process crashes

I know about how the kernel slices the CPU time to its processes, but how does it actually hand over control and take it back and what happens to taking control back when the process crashes?
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How is the process programmatically connected to an interrupt?

I know that an interrupt is a signal sent to a kernel asking for handling. In some cases we have a physical device like a keyboard with a driver that connects a process with an interrupt(key pressed). ...
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1 answer
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Why is /bin/bash /entrypoint.sh /run.sh always running?

From the moment I turn on my laptop (Ubuntu) and run htop to observe running processes, there are always these four that seem to spawn from the following command: /bin/bash /entrypoint.sh /run.sh I ...
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How to view the output of a running process in another bash session on mac?

I have a process running and I would like to know what it prints to stdout and stderr. On linux I would do tail -f /proc/<pid>/fd/1 See here How do I do this on macOS?
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Use screen to tap into process using PID? [duplicate]

I have a command running, but I don't know how to gain access to it. I closed the terminal after starting it, but it's still running. If I stop it, much progress the command has made will be lost. I ...
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1 answer
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Capture process signal "Terminated" message output in shell pipeline

When a process is ended by a signal, a message is output like Terminated or Killed depending on the signal used. Is it possible to capture that message ? Take this example pipeline: while true; do ...
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Run a command in background and independent of terminal and run alternative if fails

Goal: To run a command independent of the terminal and return immediately. And if the command fails run an alternative commands independent of the terminal and return immediately. I did the following. ...
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How to view quickly spawned/killed processes on a Fedora Linux machine?

On Windows, there is a program available for download which is part of what's called the sysinternals suite of tools. This program is called Process Explorer 64 aka ProcExp64. The program is useful ...
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What does it mean for a binary to "run as root" and how can I determine it for processes?

I've heard that vulnerabilities specifically in Linux programs (binaries in this case) that "are running as root" are dangerous because for example, if some network/web server is "...
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How to run the follow sample in own process or processes?

The Environment is a Linux like Debian or Ubuntu. I have two examples; one is working fine, the other is not. How can I fix the non working one? First example: Here, I run commands in a terminal to ...
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how to print PID along with the process dump

I wish to combine both the below commands: ps -ef| grep -v grep|grep java | awk ' {print "PID is:" $2}'; PID is:515 PID is:22145 PID is:32703 ps -ef| grep -v grep|grep java wladmin 515 ...
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Name of service/process for when copying data from mac to iphone

I mean when you copy something from your mac to the files app on iphone, not sync. Google gets confused by this question and all the results are 'how to transfer data from mac to iphone' etc. I want ...
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Start only a socat process when integrating with systemd

I want to run a "socat" command to replicate the information coming on port 162 to another machine and on the same port. I added a systemd to do this process: [Unit] Description=Socat SNMP ...
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Redirect spawned process to tempfile with the pid in its filename

Suppose myprogram is spawned through the terminal (bash) and gets pid of 1234 (different everytime). I want to redirect, both stdout and stderr, to a tempfile named abc-$PID (if the PID is 1234, use ...
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What is the meaning of `kill -0 <pid>`? [duplicate]

I found in a script a call to kill -0 <pid>. It looks like a way to check if process exists. I don't know the exact meaning of kill -0 so I looked for its definition but I didn't find any ...
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Loop over space delimited PIDs, get number of open file handles

How may I loop over a set of PIDs delimited by spaces? I think I remember the first step is like making each element its own row? For my Firefox sessions they are quite a few PIDs: $ pidof firefox ...
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How to determine which processes are running on outdated packages and needs restarting?

So, I know that it is possible to view or recover deleted files that are currently being used by a process. I've found out that this also applies to packages that were updated. So, let's say we update ...
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Jail/Sandbox process on an overlay root and track changes

What I am trying to achieve I want to run a process as an unprivileged user, but all files that are changed by this process should be only changed in a shadow folder. Furthermore, I want to disable ...
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Suspend/terminate a shell script running in background and called from another shell script

If I run the shell script below : #!/bin/bash /bin/bash loop.sh & that calls this one (loop.sh) : #!/bin/bash while true do echo "Hello" done I can't suspend it (ctrl + z) or ...
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What is the "kaluad" process on Linux?

I have been browsing running processes on my PC, and I found a process with a name "kaluad", at the time with PID 196 running under root with priority -20. I can't find it in any ...
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History process

Is there a command line to retrieve all information like pid tid of threads in Linux? For instance if one process has dead before the command ps runs. The command does not find the process
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How does round-robin scheduling and context switching work from a low-level?

Using round-robin scheduling, the kernel provides time slices for different processes / tasks. It seems that the kernel will initialize a timer, and when the timer times out, this will cause the ...
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Why is "struct pid" member `numbers` defined as an array of size 1?

I noticed that, in struct pid in pid.h, the member numbers is defined as an array of size 1. struct pid { refcount_t count; unsigned int level; spinlock_t lock; /* lists of tasks that ...
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Bash to instruct parent process to exit by certain PID's kill

How is the correct bash command/instruction to exit parent process by certain signal or PID's kill when being in child process?
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How to know which process interacts with input events

How to monitor which process interacts with /dev/input/eventX. In this case, keyboard input events. Is there a way to know which process entered a specific input and watch for that event? Is that even ...
2 votes
1 answer
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ps: show only processes owned by root, without showing kernel threads

I know how to hide kernel threads from ps: /bin/ps --pid 2 --ppid 2 --deselect -o user:10,pid,stat,pcpu,pmem,tty,start_time,cmd and I know how to show only processes owned by root: /bin/ps -U root -o ...
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Compare two Memo lines and delete unmatched lines from both Memo Delphi

I am new for Delphi 10.02 I have two Memo, Memo1 and Memo2 , both filled with lines How can I compare Memo1 lines with Memo2 lines and delete the uncompared lines from Memo2 Thanks in advance
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Finding the PORT NUMBER of the process using a specific PID?

I have a specific PID and my question is how can I know which port belongs to that PID. Any tips on how to know the port of a service that has a specific PID? Thanks a lot.
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Large process id on rocky linux 8.5

I started using rocky linux 8.5, I have added cron to reboot this server everyday. server reboots everyday. When I start some application on this server the process id I get is very large. It don't ...
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Can context switch happen without interrupts?

In my OS textbook it is written: Interrupts cause the operating system to change a CPU core from its current task and to run a kernel routine. Switching the CPU core to another process requires ...
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1 answer
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Processes in tmp folder

I have an application that has a process on the /tmp folder, and the process creates another file or folder. If the original process gets ended by the application, will all the files created by it get ...
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how to check CPU usage at linux system startup?

I am stuck on finding a way to test CPU usage for a linux system at startup, usuing top or htop is too late for me to see the real usage at startup; is there an efficient way to it ?
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How to see process ID of TCP?

When I want to see the process ID for an application I do ps -aux | grep <application>. For example, when I do ps -aux | grep ssh I see the process ID for SSH. But when I do ps -aux | grep tcp ...
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How can I look for a process that wake my machine up from suspend to RAM?

My Linux distribution is Debian 10. When the computer has been asleep (suspend to RAM), it may wake itself in random period of time. I want to figure out what causes this behavior.
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Is a file still use by php process

I have a 3.2G file in /tmp called phpvXcoZn and I need to remove it. Therefore I'd like to know if it is still in use but the commands I typed returned nothing : /tmp$ bigfile=phpvXcoZn /tmp$ ll -h $...
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lsof: print custom fields on one line

Using the -F option for lsof, I can specify which fields are printed: lsof -w -F pcfn However, the output is split on multiple lines, ie one line per field: p23022 csleep fcwd n/home/testuser frtd n/ ...
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Loading shared object to specific processes in Linux

I want to load a shared object to certain processes, there are certain conditions that are required loading to only specific processes and not all of them it has to be done before the process code ...
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macOS: ps's columns "nswap nvcsw majflt minflt" are always empty, values are correct in top

Is there a system setting to enable reporting "nswap nvcsw majflt minflt" for ps on macOS? These fields are listed in the manual installed on macOS, but their column is always empty (shows -)...
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Distinguish between kernel stack , kernel heap , process kernel stack

I read about these topics but I have some questions remained unanswered and some points I wish to verify. Kernel: 1.1. Verify: 1.1.1. The kernel is not a task nor an execution unit in the sense we ...
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Using the command "sudo chrt -r 99" for a video encoding benchmark I always get bigger (worse) times

I am using a video encoding benchmarking application. The strange thing to me is that when I am using the command sudo chrt -r 99 VideoEncoding cfg I always get bigger time (worse results) instead of ...
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How do I get process metadata for an exited process?

I'd like to read the process metadata for a process that has already exited. Say I ran a command some-bash-command and it exited. A few hours later, in another shell, I'd like to get the metadata for ...
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Error with Systemd in LFS

LFS version: 11.0-systemd Host: Ubuntu20.04 Chapter in which the problem occurred: 9.5 Commands executed: timedatectl set-local-rtc 1 Error log: System has not been booted with systemd as init system (...
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Get Window ID from PID [Wayland and X]

I saw this post here and wanted to know if there's any way to also implement the same idea - getting Window ID from PID in Wayland (or preferably, something that is protocol agnostic). X has xdotool ...
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How to detect when a terminal emulator closes from an orphaned process

I have a command line utility that spawns a daemon process which then becomes orphaned. How can I make the daemon exit along with the terminal emulator?
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What is the proper way to exit the current process from a kernel module?

I'm writing a livepatch module to hook a function and replace it with one that causes the process to terminate. I can't call abort() because that calls BUG() and my kernel will panic on oops. ...
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