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

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do processes access cpu and memory by system calls to the kernel?

If I am correct, processes access devices by system calls to the kernel. CPU and memory are also devices. when a process starts to run, does it get cpu and memory by system calls to the kernel? ...
78
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8answers
36k views

How can I disown a running process and associate it to a new screen shell?

I have a running program on a SSH shell. I want to pause it and be able to unpause its execution when I come back. One way I thought of doing that was to transfer its ownership to a screen shell, ...
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1answer
40 views

Count the total number of sub-processes (recursively) spawned by a command

How do find the total number of child processes (recursively) spawned by a script? For profiling purposes, it is sometimes important to count the generated sub-processes of command, script, etc. ...
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2answers
3k views

When was a process started

To know when was a process started, my first guess was to check the time when /proc/<pid>/cmdline was written/modified the last time. ps also shows a START field. I thought both of these ...
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0answers
56 views

Monitor the creation of new processes

I want to get a notification whenever a new process is created. I've tried to use inotify on /proc, but it didn't report any event even though a new directory appeared in /proc. I could list the ...
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1answer
104 views

Why cannot we kill a zombie? [duplicate]

I am editing this question since it was marked duplicate as another question about how to kill a zombie process. I am not looking for an answer to how to kill a zombie process. I do not have zombies ...
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4answers
375 views

New parent process when the parent process dies

In UNIX, when a parent process disappears, I thought that all child processes reset init as their parent. Is this not correct all the time? Are there any exceptions?
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1answer
2k views

What is the difference in CPU utilization between 'ps aux' and 'ps -ef'?

I use Ubuntu 12.04.1 Linux. I see a difference between %CPU and C output format of ps command for a process. It is not clearly noted in the ps man page. Man pages says: CODE HEADER ...
2
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0answers
38 views

What uses Linux “application memory”?

Just for fun, I wanted to watch what ls -lR / does to my "buffers" memory on a Linux system. As expected, the value increased. But I noticed that the "application memory" (i.e. "used" - (buffers + ...
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6answers
691 views

grep invading my ps [duplicate]

When I'm checking for some process, I usually write ps aux | grep myprocess And sometimes I get the output of eimantas 11998 0.0 0.0 8816 740 pts/0 S+ 07:45 0:00 grep myprocess if ...
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1answer
1k views

Program stall under user but runs under root

I am running R job under a normal user john and root. Interestingly, the program stalls under john user but runs quickly under root. Using strace, I found that when john runs the R, the process stalls ...
3
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1answer
5k views

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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1answer
48 views

“incrond dead but subsys locked” what does it mean?

While running "service incrond status" it shows "incrond dead but subsys locked". Can you please tell me what does it means. Normally its status should be running. Let me know what may cause it to ...
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1answer
394 views

Very large values for utime and stime for foo. Is foo still running?

I am running a program foo It has been running for close to 30 days now (even more) Until around 10 days ago (I cannot be very exact) it used 100% of one cpu on my dual core laptop (it was at the ...
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1answer
39 views

fork() and how signals are delivered to processes

I program that I wrote in C fork()'s off a child process. Neither process will terminate. If I launch the program from the command line and press control-c which process(es) will receive the interrupt ...
2
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0answers
41 views

Determine the owner of the session of a process

I am trying to implement a way to determine which user is owner of some process's session, in a way that's as cross-platform as possible. In Linux I can trace the process's pty by following the link ...
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1answer
60 views

Equivalent command for ``time`` for memory usage?

by using time we can easily get the information about how long a program run, I was wondering if there is any equivalent command I can use for memory usages? Like how many memory are allocated for ...
2
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1answer
74 views

Bash update list of running jobs with ps

I need to run in parallel a set of computationally intensive tasks. What I was trying to do is to maintain a list of pids corresponding to the running jobs and update the list of running jobs with ps ...
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5answers
613 views

How to kill stubborn process

I've an annoying process that won't die: ps -A | grep "nzbget" gives me: 11394 pts/3 00:00:00 nzbget If I try: pkill nzbget (or 11394) ...I get no response and the process is still alive, ...
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1answer
1k views

Process history in Unix/Linux systems

I know that ps -efl shows running processes on *nix systems. I would like to check history of the (past) processes that have been run on a particular machine, preferably with all the information ps ...
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2answers
63 views

A process is a program that is loaded into RAM [closed]

Is this correct? Basically, programs are simply code on hard disk and they are called process(es) when they are in the RAM, right?
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2answers
73 views

Can Process id and session id of a daemon differ?

As far as I understood from different articles and here , a daemon has the following features: Parent Process ID should be 1. No terminal should be associated with the process. The process id, ...
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5answers
52k views

How to stop a background process?

I have started a wget on remote machine in background using &. Suddenly it stops downloading. I want to stop its process, then start it again. How can I stop it? I haven't close its shell window. ...
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1answer
70 views

'htop' process and threads cpu usage?

I'm observing a multi threaded process in htop in tree view. If I were to strip it just to the problematic part, it looks somewhat like this: CPU% bin/process 100 `- ...
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0answers
63 views

pkill -P $ID working while kill — -$ID not

I was playing around with creating and killing process groups on linux ( ubuntu ) I am trying to kill a process group and am being driven crazy by the fact that pkill -P $ID works while kill -- -$ID ...
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1answer
55 views

Process id of a command ran by an user

Consider i am running just some basic command.. ls Now would the above command have a pid, when it was getting executed? If yes, then how can i determine that pid? when i try echo $! right ...
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1answer
47 views

Retrieve X11 window ID of a just-launched GUI-program

I want to retrieve the X id of GUI programs I launch in background, in order to work on their windows properties. I've been so far using this workaround: myprogram & sleep 1 winID=$(wmctrl -l | ...
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3answers
370 views

How can I start a process with any name which does nothing?

I want to start a process that does nothing but is still running. Say I start a process called sadhadxk, and when I run pgrep -x "sadhadxk" I will get the PID number back, like any normal process ...
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2answers
137 views

Sorting the output of `ps`

I am trying to understand why ps does not behave the way I expect it to. From the man pages, the following command should display ppid and lstart, with items sorted by lstart order. However when I run ...
2
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1answer
79 views

Find out to which directory a process is writing?

This question is NOT a duplicate of this question Find out current working directory of a running process?, because the writing directory can be different from the working directory. For example, I ...
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2answers
108 views

gracefully terminating processes with killall <processname>

I am using several instances (profiles) of Icedove (Thunderbird) and when I need to close all of them, I use: killall icedove According to man killall, if no signal name is specified, SIGTERM is ...
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2answers
38 views

using sudo create another process

I have wrote a shell script names testShell.I run this shell using command: sudo sh testShell Then I use ps -ef|grep testShell|grep -v grep to check the processes created.I find that system ...
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1answer
83 views

Pipe stdout to command on stdout

If I had a running process like tail -F watch.txt and I wanted to capture the stdout from this running process and pipe it to another command on stdout how could this be done? Here's an example of a ...
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1answer
24 views

PID in top different from the $$ one?

I have been always running my following job. #!/bin/sh NO_START=1 STEP_SIZE=1 NO_END=100 DATE_STR=$(date +%m%d_%H%M%S) RUN_DIR=./$DATE_STR mkdir $RUN_DIR echo PID = $$. See $RUN_DIR/$$.log for ...
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1answer
55 views

command “jobs” cannot see the stopped jobs

I have wrote a very simple shell script to practice command "bg" , "fg" and "jobs": #!/bin/bash myvar=1 while [ $myvar -le 100000000 ] do echo $myvar myvar=$(( $myvar + 1 )) done I use ...
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1answer
99 views

What is JID (job ID) and is it always smaller than PID? [closed]

I don't know what exactly is JID (job ID) and how it is assigned. What is it's relation to PID and how does one number affect the size of the other in any way?
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1answer
42 views

How to suspend a process for a certain period of time?

I have several running processes which is started by a shell, but I don't want them to run during 08:00am - 20:00pm for each day because they are really bandwidth-consuming, so , I have to suspend ...
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0answers
37 views

What does the “k” metric mean in the “sa” output?

From man sa: k cpu-time averaged core usage, in 1k units My questions: How is it calculated? What is the significance?
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1answer
21 views

Mechanism of multiple call for one script in the same time

Maybe this question is stupid Anyway I have the ruby script which is calling from different places in the same time(with defferent options). Is it safely and how this mechanism realized in linux? I ...
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1answer
29 views

screen manager with VT100/ANSI terminal emulation

If I join with 'screen' to existing sessions, I can get a list of the sessions with C-a " keystroke and switch between them, however I can't find a way to safely leave/detach and keep all the ...
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1answer
19 views

list processes running inside of screen (manager with with VT100/ANSI terminal emulation)

I have an application that during installation runs a bunch of processes via screen, so I can see those if attached to the screen, however I don't see those via "ps -ef" or "ps auxww". How can I list ...
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1answer
31 views

CPU time that accton (psacct) records - recorded time relationship between parent and children processes

I've had 'accton' (in package psacct-6.3.2-63.el6_3.3.x86_64) turned on as I want to be able to report on a particular process (so I've written a script that will take the psacct file and get the ...
0
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1answer
45 views

Why PPID is different when opening from terminal and when opening by doubleclicking

I am using Linux. When i opened gedit program in gnome-terminal by gedit command it has opened the graphical gedit text editor. then the gedit has PPID bash ...
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2answers
60 views

Creating background process and communicating with it

1st thing off, I am really a Linux newbie - knowing just some basics; there's a great chance I didn't know what I need to look for, please redirect me if you know a good source. What I'm trying to do ...
11
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4answers
10k views

How to see how many context switches a process makes?

I want to see if my process makes a lot of context switches. I also want to see how manpulating task groups affects the number of context switches.
0
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1answer
69 views

How to move a background job from one terminal tab to another? [duplicate]

I have a background job, say jobid 1, in a tab of gnome terminal. Can I move it to a another tab of genome terminal? I understand that the shell process in the first gnome terminal tab is the parent ...
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0answers
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Why are some processes “killable” by pkill but not killall?

I had over 20 instances of httpd (apache) processes running, so I decided to shutdown these. Normally I use killall, But when I typed killall httpd it just said: No matching processes belonging to ...
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1answer
116 views

grep for specific process in ps but not the grep command itself [duplicate]

If I want to check if something is running, I do ps aux | grep flamethrower, expecting just to show the processes containing flamethrower in the name. This will always find at least one process, as ...
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1answer
64 views

Why kernel threads are treated as processes

In output of the ps command like the one below (kthreadd,ksoftirqd,kworker) , i can see that there are some processes that don't have an executable file and i find out that's because they are kernel ...
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4answers
18k views

Show running processes with file name(s)?

I am using putty to connect my linux server which my sites are in. I can run # ps aux | less to show running processes. But I want to display which files running these processes ? I have also ...