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

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What is meant by “Unknown instance” when restarting a service?

I am trying to get vsftpd file server running on Ubuntu 13.10, I'm unable to connect to the server from another network, although this other network is connected to the server's network and ping is ...
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62 views

Monitoring filesystem activity

Say, I have a program, and I want to monitor its filesystem activity (what files/directories are created/modified/deleted etc.) This program may be capable of spawning further processes, and thus, I ...
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85 views

How to find out the reason a command/code was executed on Linux?

I have a complex embedded Linux software running on a gentoo derivative, on which a certain piece of code gets executed regularly every ~84 minutes. Sweeping through the main code to find places where ...
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203 views

How does the piping in this command ultimately achieve to kill the process?

I have seen the following line in a bash script for killing a process(in this case started with the command loadgen): ps xww | grep -i "loadgen" | grep "PATTERNMATCH_FACT.xml" | cut -c1-5 | xargs -i ...
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317 views

Bind9 — How to find which programs are making which dns lookups?

Using bind9 on a laptop shows lots of nonsense domains when network connectivity is down: Oct 18 19:56:18 lap3 named[1536]: error (network unreachable) resolving './NS/IN': 128.63.2.53#53 Oct 18 ...
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89 views

How can I recover suspended processes after restarting X?

I had several instances of Firefox running, which I suspended. I think I used 'the GUI' (KDE's System Activity), which I think is the same as kill -19. Normally this works fine - I can resume the ...
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222 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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162 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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444 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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6k views

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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3k views

kill a group of processes with negative PID

kill -TERM -PID is supposed to kill PID and all its child processes. but this doesn't work on openSUSE, it always tell me that no such process -PID no matter what PID i use. So if the negative PID ...
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645 views

What process is sending TCP SYNs on Solaris 10?

Some process on my Solaris 10 machine is sending TCP SYNs to a remote machine. The remote machine never responds, so the connection is not established. How do I find out what process is initiating ...
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3k views

Understanding ps elapsed time format for long running processes

I'm using a ps command as part of an exercise to identify processes running longer than a given threshold. I'm using the following template to get the elapsed time for a know process command: ps -eo ...
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478 views

wait does not wait

If i have a file called myprogram containing sleep 200 date Run this in the background: $ sh myprogram & i want to know when myprogram has completed by using wait command $ cat >notify ...
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4k views

Fork bomb on a Mac?

I just learned about a fork bomb, an interesting type of a denial of service attack. Wikipedia (and a few other places) suggest using :(){ :|:& };: on UNIX machines to fork the process an infine ...
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785 views

Questions on Linux kernel internals

I was reading "Linux device drivers, 3rd edition" and faced a few kernel items I don't quite understand. Hope gurus on this forum will help me out. Does the Linux kernel internally operate with ...
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83 views

How can I get the wall clock time of a running process?

I started a hash check of a large file and don't want to restart it using time. How can I get the wall clock time without using time at the beginning or using date right before I invoke a command?
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49 views

Result from kernel returned to what process?

When a process requires actions that require kernel mode, it uses a system call. So, how are the results returned to the process?
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747 views

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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bash: Run command in background and capture pid [duplicate]

Am writing a bash 4.1 script... Would like run another script (or internal function) in the background... And capture the pid of that background job in a variable in the foreground script... If the ...
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350 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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328 views

Print process ID (PID) of a Matlab instance

To run my Matlab scripts, I've created a shell script to which I give two parameters - the path to the matlab file ($1) and to the log file ($2): nohup time matlab -some_parameters -r "run $1;exit" ...
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578 views

Capture complete process structure/stack

There are a lot of java processes running on the server, generally, we capture the PIDs of the java processes using command 'ps -ef | grep java'. In general, the java processes have a lot of jars in ...
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296 views

How to know which commands are executed when I do something in GUI

This is for academic purpose. I want to know which commands are executed when we do something in GUI, for example creating a folder. I want to show that both the mkdir shell command and create folder ...
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330 views

Prevent users from killing processes that they own

I have started some processes (window based) from user's .bashrc file. I want to prevent users from killing those processes. Is there a way to transfer the process to superuser so that a normal user ...
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450 views

Rationale for making user space text segment start at 0x8048000

I read somewhere that (at least since Linux v. 2.6) all user-space code is placed at load address 0x8048000 in the virtual memory address space. My own observations confirm this. I have done a cat ...
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738 views

How can I kill the top CPU/IO process quickly?

I find that sometimes my Linux will stop responding, so I need to switch to another terminal with CtrlAltF2, and type a command to kill the top CPU usage process or top IO usage process, so that the ...
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408 views

Redirecting/grep'ing an existing shell's STDOUT

I run a lot of long running processes (simulations) that print progress to STDOUT. I occasionally forget to redirect to STDOUT to a file I can grep, and it's usually too far along to restart. ...
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633 views

Solution to get data from memory of a process

If I'm using Firefox and filling out a big form (with lots of text to write), and for some reason I accidentally press F5 and all my text in the forms is lost, I can use e.g. HxD on Windows to ...
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262 views

Linux system calls

I want to obtain information about memory used by different users and different processes which users are running and statistics about those processes like memory consumption ,execution speed etc ...
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What does it mean exactly when a processes “Time” has stopped in top?

I'll be looking into why we're getting critical swap alerts, and I'll find something like: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ SWAP COMMAND 14683 user1 30 10 16.0g 772m ...
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231 views

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

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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189 views

Get PID of the application running in the active terminal emulator

My end goal is to be able to open a new terminal window (urxvt) directly in the current working directory of the program running in the window currently active. I'm currently using the shell (Bash), ...
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Why “uninterruptible sleep” is not counted as “IDLE”?

When I run top -bi, where the parameter -i means "ignore idle processes", the resulted list(see below) of processes are either R or D, although there're S processes at that time. So, why ...
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Cannot kill a java process

I have a java process that cannot be killed. I have tried every method I know, or that I have found on the internet to no avail. I have tried: killall java kill -9 <pid> kill -11 <pid> ...
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120 views

Get process list with logical intersection of selectors?

The Linux ps command allows multiple selectors, such as user and command name, but always returns the logical OR of those selectors (more than I want). Does anyone know of a method or tool already ...
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135 views

how to disallow user to change process group

Is it possible to restrict a process from changing it's process group? For example, user nobody seems to be able to call setpgid(0, 0) which sets process group of current process to pid of that ...
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316 views

Kill process when it stops to produce further output

Is there a shell tool which can probe if a subprocess is still producing output, and otherwise kill it after a specified timeout? I'm using offlineimap for Gmail backup, but that's very very very ...
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1k views

A tee >( process ) is truncating its stdout when writing a file

When I use tee to pipe stdout directly to a "specific block of code" (which then writes the modified data to a file), I always get the full complement of exptected output lines in the file. ...
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664 views

Difference between process group and job?

What's the difference between a process group and a job? If I type pr * | lpr then is it both a process group as well a job? What exactly is the difference between a process group ID and a job ID? ...
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CPU percentage of a single process

How do I get the average CPU percentage (for every second) consumed by a single process since it starts until it ends (exists)? Could I make this with Top?
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55 views

Is each process considered a thread?

Is a Linux process considered a thread? For example, if I write a simple c program that calls pthread_create to create a new thread in main(), does that mean that I now have 2 threads, one for ...
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193 views

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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76 views

What is the rtsbpp-polling process doing?

In Ubuntu 12.04 LTS when I run the top command I see a process called rtsbpp-polling. Googling it gives only just a few hits to the Gentoo Linux forum that does not seem to be relevant (they don't ...
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724 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 ...
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921 views

When do jiffies increment? How a process runs in a jiffy?

I know that jiffies length is selected at kernel compile time and it is defaulted to 250 (4ms). Source: man 7 time - The Software Clock, HZ, and Jiffies I wonder what happens inside a jiffy. What are ...
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584 views

How do I detach a process from its parent? [duplicate]

Possible Duplicate: How can I disown a running process and associate it to a new screen shell? The problem is that the process is not a job inside of my active shell (as I've logged in from ...
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959 views

Limit process resource consumption in CentOS 5 (2.6.18 kernel)

I would like to limit the resource (CPU, Memory, and network bandwidth) consumption of processes on the same server. And it will be good if I can migrate processes from one server to another. I ...
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990 views

How to trace a process to original user?

Say, on a Solaris server, user1 logs in, switches to someother user, say sruser, using su - and then starts a process of id X. And then another user user2 logs in, switches to sruser the same way and ...
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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 ...