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

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21
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Who's got the other end of this unix socketpair?

I want to determine what process has the other end of a unix socket, that was created with socketpair(). I have a program parent which creates a socketpair(AF_UNIX, SOCK_STREAM, 0, fds), and fork()s. ...
29
votes
2answers
2k views

Why is the default process creation mechanism fork?

The UNIX system call for process creation, fork(), creates a child process by copying the parent process. My understanding is that this is almost always followed by a call to exec() to replace the ...
22
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2answers
5k views

What is the difference between a job and a process?

What is the difference between a "job" and a "process"?
13
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1answer
4k views

init process: ancestor of all processes?

I have always learned that the init process is the ancestor of all processes. Why does process 2 have a PPID of 0? $ ps -ef | head -n 3 UID PID PPID C STIME TTY TIME CMD root ...
10
votes
1answer
6k views

How to suspend and resume processes like bash does

this question is a follow-up to: How to suspend and resume processes I have started firefox from a bash session in gnome-terminal. The process tree looks like this: $ ps -e -o pid,ppid,cmd -H 1828 ...
18
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2answers
5k views

Why does `htop` show more process than `ps`

In ps xf 26395 pts/78 Ss 0:00 \_ bash 27016 pts/78 Sl+ 0:04 | \_ unicorn_rails master -c config/unicorn.rb 27042 pts/78 Sl+ 0:00 | ...
21
votes
2answers
570 views

When you try to terminate a process for good, which option for “kill” should you use?

I am getting a lot of mixed messages from people, and was wondering if it there really is not much of a difference in what you use. kill 'x' killall 'x' kill -9 'x' These are some options I've been ...
8
votes
1answer
354 views

how to find out namespace of a particular process?

I already asked a question about how to list all namespaces in Linux, but there wasn't any correct and exact answers, so I want to find out a method which can help me to find out the namespace of PID ...
7
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2answers
2k views

How can you determine which process scheduler is being used? [duplicate]

I.e. is it the O(1) scheduler, the CFS scheduler, or an older one?
7
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1answer
2k views

Is the sum of all PIDs “utime” the total system utime?

In order to measure a user's total CPU time, I'm using the "utime" field out of /proc/[pid]/stat: utime %lu Amount of time that this process has been scheduled in user mode, measured in ...
6
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3answers
655 views

Running continuous jobs remotely

I'm new to Linux, and I'm probably asking a fairly basic question. How do I run a continuous program on Linux? Basically, I have a program that will continuously check for content on a website. This ...
5
votes
3answers
30k views

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 ...
3
votes
1answer
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? ...
2
votes
1answer
455 views

What process created this window with no PID associated? [duplicate]

Possible Duplicate: What process created this X11 window? I need to kill a process that spawned a window which seems to have no PID associated with it. At least that is what xdotool says: ...
15
votes
1answer
5k views

What is the maximum value of the PID of a process?

What is the maximum value of the PID of a process? Also, is it possible to change the PID of a running process?
8
votes
6answers
6k views

Kill many instances of a running process with one command

This is one of the questions that has troubled me often. Suppose I have thousand or more instances of any process(for e.g. say the process vi) running. How do I kill them all in one single shot/one ...
7
votes
3answers
4k views

nohup vs. Screen

In the past, I've used nohup to run big background jobs, but I've noticed that a lot of people use Screen in this context. Does Screen provide some kind of functional advantage that I am unaware of, ...
6
votes
3answers
288 views

Understanding environmental variables in different contexts

Trying to understand the behaviour of the environment in Linux (Ubuntu 13.04 concretely), I've find different situations where setting envirionment variables are used or defined for/in different ...
6
votes
2answers
973 views

Is it possible to transfer a running process to your terminal? [duplicate]

Possible Duplicate: How can I pause up a running process over ssh, disown it, associate it to a new screen shell and unpause it? It is fairly easy to disown a process, or make it run ...
3
votes
2answers
396 views

I need help with a cronjob to watch for runaway processes and kill them

I have an interesting situation, I have a runaway ruby process - I know exactly how I trigger it. Point is, it got me thinking about runaway processes (CPU usage or memory usage). How would one ...
12
votes
3answers
16k views

Find and remove large files that are open but have been deleted

How does one find large files that have been deleted but are still open in an application? How can one remove such a file, even though a process has it open? The situation is that we are running a ...
12
votes
4answers
670 views

What is the difference between running a executable just by name and by appending a dot /slash before it?

This is the output from ls -all command : -rwxr----- 1 subhrcho dba 3600 Nov 13 17:26 jdev -rw-r----- 1 subhrcho dba 1566 Nov 13 17:26 jdev-Darwin.conf -rw-r----- 1 subhrcho dba 347 Mar 6 2009 ...
7
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3answers
309 views

Harddrive I/O per Pid

is there any way to see the disk I/O per pid/process ? Monitorix shows me the following and correct me if I´m wrong, but it looks like that the harddrive is slowing down the whole system: UPDATE #1 ...
6
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3answers
264 views

Why is I/O uninterruptible?

What is the rationale behind making I/O uninterruptible? What would be the negative consequences if a process handling I/O were allowed to handle a signal?
5
votes
3answers
304 views

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 ...
5
votes
1answer
2k views

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, ...
5
votes
1answer
233 views

Why is the following command killing a system?

Anyone understand the following code , running in bash ? :(){ :|:& };: It seems to be a "fork" bomb on Linux.
4
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2answers
189 views

LD_PRELOAD or similar to prevent network access

I'd like to start a program disconnected from the network (because immediately upon starting it tries to download huge amounts of data, which can be prevented by changing settings as soon as it ...
14
votes
3answers
7k views

Which process has PID 0?

I'm looking for the process started in Linux which has process ID 0. I know init has PID 1 , which is the first process in Linux, is there any process with PID 0?
7
votes
1answer
146 views

Simulate an unkillable process in D state

For catastrophe testing scenarios on out server environment we're looking for an easy way to make a process stuck in D (uninterruptible sleep) state. Any easy ways? An example C sample code would be ...
7
votes
3answers
1k views

Elegantly get list of descendant processes

I would like to get a list of all the processes that descend (e.g. children, grand-children, etc) from $pid. This is the simplest way I've come up with: pstree -p $pid | tr "\n" " " |sed "s/[^0-9]/ ...
5
votes
2answers
324 views

How can I allow a user to prioritize a process to negative niceness?

I want a user to run a specific process on the system with a negative nice value. I can't simply fork the process to background as this specific program is a minecraft server and I rely on the command ...
5
votes
3answers
273 views

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 ...
4
votes
1answer
93 views

Maximum memory usable by a 32 bit RHEL 6 system

I have installed a 32 bit RHEL OS on a 64 bit system. From the wiki page of PAE: The Linux kernel includes full PAE mode support starting with version 2.3.23, with Linus Torvalds mentioning ...
4
votes
2answers
5k views

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 ...
4
votes
4answers
419 views

why new pid is smaller than the old ones?

Is there any chance the new process's pid is smaller than the existed ones ? I have a daemon process which will restart when be killed, I recorded the pids, and found that the pid first came smaller, ...
3
votes
4answers
393 views

Keeping a process running on server even SSH is closed [duplicate]

I am running long program on server, which is basically Jar file of java program. I want to keep this program running even if SSH terminal is closed, how I can keep this program running on server?
3
votes
4answers
2k views

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 ...
3
votes
4answers
445 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 ...
2
votes
0answers
24 views

CGroup Processes Not Terminated even when main process has been killed through Systemctl stop command

I am running systemctl stop process command for some process. Please find the output for systemctl status process below: Loaded: loaded Active: deactivating (stop-sigterm) CGroup: ...
2
votes
1answer
155 views

Obtain user and kernel time of a running process?

Is there way to determine using standard Linux/Unix tools how much a process has spent in User mode and how much waiting for kernel? In other words, exactly the "user" and "sys" values that you get ...
2
votes
0answers
206 views

How is it that I can attach strace to a process that isn't in the output of ps?

I'm trying to debug why our integration tests are taking so long and it looks like they're hanging part way through. I logged onto our test service and saw the following behaviour: root@colossus:~# ...
2
votes
1answer
212 views

Why does't stopping the nginx server kill the processes associated with it?

When I stop nginx like this on ubuntu 12.04, I get the following errors: $ sudo service nginx stop Stopping nginx: nginx. $sudo service nginx start Starting nginx: nginx: [emerg] bind() to 0.0.0.0:80 ...
2
votes
2answers
103 views

How to get environmental variables of a very short process?

I have a very short process for which i want to check the environmental variables for debugging purposes. The process is instant from a human perspective. The example illustrates it better. Example ...
2
votes
3answers
2k views

pkill can't kill processes with parent process id 1

I want to kill the following processes using pkill "run_tcp_sender.sh" or pkill -SIGKILL "run_tcp_sender.sh" root 14320 1 0 2012 ? 00:00:00 bash run_tcp_sender.sh ...
2
votes
2answers
652 views

Is there any impact of reaping zombie processes?

I will execute following command for reaping zombie /usr/bin/preap $(ps -ef | grep defunct | grep -v grep | awk '{ print $2 }' | xargs) Is there any service impact of this approach ?
1
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3answers
110 views

detect process eating cpu without: top, htop, ps?

I went thru a problem where I could only guess what process was eating the cpu. My cpu usage was about 80% for all cores at psensor. I tried htop, top and ps -A -o pcpu,pid,cmd --sort +pcpu (the ...
1
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3answers
122 views

How do I start a server via ssh and have it run after I log out?

I ssh into a virtual server and start up a web server. Everything runs as expected. But when I close my terminal on my laptop, the process dies on the virtual server. How do I fix this?
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2answers
578 views

“ps” command doesn't return to prompt

I have this linux box that I need to maintain periodically. To do that, I issue a ps command programmatically and check the running processes. But as shown in the screenshot, sometimes, the ps ...
1
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2answers
120 views

Terminal command (called not from SU) that would restrict process from writting to all directories but one?

We have an app testApp. We have a folder called notRestricted in the directory where we run app from. We want to limit access of the app to file system so that app could write only to that folder (we ...