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

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How to check how long a process ran after it finished?

Currently I'm using the following to check how long a process is actually running: ps -eo uid,pid,etime | egrep '^ *MY_ID' | egrep 'PID_OF_PROCESS' And that outputs the following: MY_ID ...
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Portability of file descriptor links

I've always wondered this but never took the time to find out, so I'll do so now - how portable is the usage shown here of either /proc/$$/fd/$N or /dev/fd/$N? I understand POSIX guarantees /dev/null, ...
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Is it possible to support multiple processes without support for Virtual memory?

Is it possible to support multiple processes without support for virtual memory? I would like to know more about it if so.
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How can I see what processes are running?

I use Ubuntu Server 10.10 and I would like to see what processes are running. I know that PostgreSQL is running on my machine but I can not see it with the top or ps commands, so I assume that they ...
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Processes in Linux

As I understand it, process descriptors are stored in a doubly linked list data structure. But a fork can create multiple children for the same process, so that makes me think that there is a tree ...
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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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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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Is grandchild process also child process?

In Unix/Linux terminology, do child processes of a process include grandchild processes of the process?
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Dynamic file content generation: Satisfying a 'file open' by a 'process execution'

I have a read-only file, F. A program, P, that I'm not the author of, needs to read F. I want the content of F to come from another 'generator' program, G, whenever P tries to read F (taking F to ...
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root owned program with setuid bit on

Ping is a a program owned by root with the user id bit set. $ ls -l `which ping` -rwsr-xr-x 1 root root 35752 Nov 4 2011 /bin/ping As I understand it, if a user runs the ping process, then the ...
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Find processes using a network interface

I'm trying to find a way to safely shutdown a network interface, i.e. without disturbing any processes. For this I need to find out what processes are currently using that interface. Tools like ss, ...
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Do sleeping processes get the same CPU time?

Some processes spend most of their "lives" in a sleep status. Daemons, servers and general listener come to mind. I was wondering if they get the same CPU time in that state? On something like my ...
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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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How can you change the process name of Wing IDE from python to something more descriptive

In my process list under Ubuntu (using top/System Monitor) one of the largest memory hogs (200+Mb) was python. I searched a bit for one of my programs to be the cause until I realised this was my ...
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How to poll existence of a background script correctly

I have a problem with the following kind of script: #!/bin/sh long_running_script.sh & while [ `pidof long_running_script.sh` ] do echo "." sleep 1 done The sript will ...
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Preventing program from using internet

Is there a way to block certain programs from being able to connect to the internet in Debian (a firewall blocking outgoing connections), so for example, to block a windows program running in wine ...
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Obtaining PID of command earlier in Pipeline

I'm writing a bash script to use inotifywait to monitor a directory and kick off actions when changes are detected. Something like: inotifywait -m ... | while read f; do something; done Since ...
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Is there a way to really prioritize processes or make Linux respect their priorities?

I know there are process priorities like in other operating systems, going from -20 (most prio) to 19 (less prio) but Linux seems to ignore them. Right now I was building the kernel in the background ...
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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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What is kondemand?

I have searched the web for the answer of this question but couldn't find a clear answer. Best answer I found was as follows: kondemand is a kernel thread that belongs to the ondemand governor of ...
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mmap() failed: Cannot allocate memory - how do I find out who's complaining?

mmap() failed is popping up in my .xsession-errors in bursts. But there's no indication about what application it is failing with. How do I look into this after it has happened? I usually discover the ...
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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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Why does `bash -c somecommand` sometimes not leave a bash process?

On an Ubuntu 12.04, with GNU bash, version 4.2.25(1)-release (x86_64-pc-linux-gnu), I tried the following command: $ bash -c 'pstree -s $$' init───sshd───sshd───sshd───bash───pstree $ bash -c 'pstree ...
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Why do forked processes sometimes appear with brackets [] around their name in ps? [duplicate]

On a Linux system a C process is started on boot, which creates a fork of itself. It is not a kernal process or something. In most cases a ps -ef show both processes as expecxted, but sometimes it ...
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Get the PID of file creation

I am writing a bash script that creates 5 files with the extension ".P" and write a line of "something" into them. "P" represents a number and it's the PID of the process that creates the file. How ...
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Bash script wait for processes and get return code

I am trying to create a script which will start many background command. For each background command I need to get the return code. I have been trying the following script : #!/bin/bash set -x ...
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How to track the number of processes and forks per user?

I need to figure out how many forks are done and how many concurrent processes are run by each user over time. It does not look like this information is tracked by my distribution. I know how to ...
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Launch independent process [duplicate]

Possible Duplicate: How can I close a terminal without killing the command running in it? If I open a terminal emulator, type firefox & and then close the terminal, the process it ...
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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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Number of running processes show in top

The usual maximum number that I have seen in the "running" field displayed in top(1) is the number of logical CPUs installed in the system. However, I have observed that under Ubuntu 10.04 (not ...
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What causes /proc/<pid>/* resources to become owned by root, despite the procs being launched as a normal user?

I've noticed that some procs, such as bash, have their entire /proc/<pid>/ resources readable by the user who created that proc. However other procs, such as chrome or gnome-keyring-daemon, have ...
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Processes do not respond to my signals

I have a strange behavior on my system. When I invoke a command in the shell (bash version 4.2.45(1)-release), say top or cat, the running program (the process) does not respond to Ctrl+C. I even ...
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Why do top and ps show different PIDs for the same processes?

When I run top -H, I see that my multiple mysql threads all have the same PID. However, in ps -eLf I see each one has a different PID: ps -eLf UID PID PPID LWP C NLWP STIME TTY ...
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Running multiple nohup commands in background

Got two commands cmd1 and cmd2. Of the two, cmd2 takes longer to finish. Need to run cmd2 and then cmd1. Tried to run them in following way: bash$ (nohup ./cmd2>result2 &) && nohup ...
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Difference between poll_s and ep_poll WCHAN in ps output

When I issue ps -elf|grep python for example on my system, I see these: 1 S 1000 6020 6008 0 80 0 - 9914 poll_s Jul12 ? 00:00:01 python manage.py run_gunicorn -t 3600 -w 8 -b ...
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Real time processes scheduling in Linux

I have been learning some scheduling concepts. Currently my understanding so far is as below. There are real time processes and non real time processes. Non real time processes can have nice values ...
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How disk IO priority is related with process priority?

I'm running software that overloads disk IO sometimes. I don't need fast response from that software, I need fast response from other applications, so I could set low process priority for that. I want ...
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Get CPU usage for single process

I've got a problem getting a real-time CPU usage of a single process (by its PID). I'd like to setup a watchdog for the CPU usage of a process because it's suddenly reaching 100% of the CPU usage ...
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What is a process GID and what purpose does it serve?

Reading mod_wsgi's documentation I found you can choose which group to run the worker processes as. I can understand group ownership of files and how only a user who belongs to that group can achieve ...
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What is “automatic stack expansion”?

getrlimit(2) has the following definition in the man pages: RLIMIT_AS The maximum size of the process's virtual memory (address space) in bytes. This limit affects calls to brk(2), mmap(2) and ...
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Can I add to my groups in the current (shell) process? [duplicate]

If I add myself to a group, it applies only to newly launched processes. Actually it's more restricted than that; it seems to apply only to new logins. I'm not sure what the exact mechanism is, but ...
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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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Getting disk i/o statistics for single process in Linux

I need to monitor the I/O statistics of a process that writes to disk. The purpose is to avoid write rates too high for long periods. I know there's iostat tool to accomplish this task on a ...
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What are pending signals?

When looking at the limits of a running process, I see Max pending signals 15725 What is this? How can I determine a sensible value for a busy service? Generally, I can't seem to find a ...
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Is the Unix process scheduler itself a process?

Is the Unix process scheduler itself a process, or does it piggyback on other processes in the same way a system call does (running kernel code in the user process with the kernel bit set)?
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What information can I find out about an eventpoll on a running thread?

Following on from a problem described in "How is it that I can attach strace to a process that isn't in the output of ps?" I'm trying to debug a process that hangs part way through. By using ...
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Linux : See CPU usage by a process for the last second

vmstat 1 Above will print virtual memory statistics each seconds. It will also show the CPU utilization for last second. I have a web server at hand which runs httpd and MySQL. I need to find how ...
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How to monitor all executions of an executable over a time period

I know how to monitor a process. Commands like top and so forth can monitor the CPU time and memory usage for a given process instance. But say I expect a given executable to be run several times in ...
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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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Find what process implements a FUSE filesystem

How can I get the process ID of the driver of a FUSE filesystem? For example, I currently have two SSHFS filesystems mounted on a Linux machine: $ grep sshfs /proc/mounts host:dir1 ...