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

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21
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3answers
22k 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?
-2
votes
1answer
94 views

How are zombie processes handled when the parent dies?

Which technique does the Unix system use to remove zombie processes whose parent has terminated?
4
votes
4answers
295 views

Are the states of processes which are ready and scheduled to wait “S”?

In the output of top, the state S means interruptible sleep. What is the state of those processes which are scheduled to be ready and waiting for execution in CPU by the scheduler? Is it S or ...
3
votes
4answers
216 views

How to get the PID of a sub process across to the parent process in a bash shell script?

My shell script is as following: #!/bin/bash ./process1 #It will create a sub process: sub_process1 while [ condition ]; do break done kill -9 process1 and sub_process1 In my script, it will ...
0
votes
2answers
31 views

Is there a need to get rid of a zombie process? [duplicate]

I read somewhere (forgot where) that a zombie process continues to consume the process table entry (concretely the process identifier or PID), and causes a resource leak. Is it correct that a zombie ...
0
votes
2answers
1k views

How to disable core dump generation in Centos (cPanel Server)?

I want to disable core dump generation, How can I disable it ? One of the website keeps generating core dumps every second and eats up all the disk space. OS Details: CentOs cPanel Server ...
5
votes
2answers
352 views

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 ...
5
votes
4answers
302 views

Run multiple commands and kill them as one in bash

I want to run multiple commands (processes) on a single shell. All of them have own continuous output and don't stop. Running them in the background breaks Ctrl-C. I would like to run them as a single ...
2
votes
0answers
32 views

Identify process

Every couple of minutes my Mac OSX machine starts running a process that consumes 10% of the CPU. It runs for a couple of seconds and then stops. I can see the process coming up in 'Top', but the name ...
4
votes
0answers
74 views

Is it possible to make an exec call that “returns”?

Is there a way to make the exec system call work like a function call that returns instead of totally replacing the current process image? My motivation is trying to integrate two shells with ...
1
vote
0answers
52 views

Create tree of processes

I'm implementing pstree as an assignment, and I would like to create test tree of processes, but I'm struggling to do so. I tried to do something like this to create tree of background processes ...
0
votes
1answer
34 views

Killall processes under a user?

So, I know you can pkill -U <uid>, but whenever I've used this, my entire system crashes. Further investigation shows it probably is because I'm not matching anything, so it matches everything? ...
35
votes
1answer
48k views

There are stopped jobs (on bash exit)

I get the message There are stopped jobs. when i try to exit a bash shell sometimes. Here is a reproducible scenario in python 2.x: ctrl+c is handled by the interpreter as an exception. ctrl+z ...
3
votes
3answers
4k views

Cron job to check if PHP script is running, if not then run

I am wondering if someone might point me in the right direction. I've got little experience working with the Linux command line and recently due to various factors in work I've been required to gain ...
0
votes
1answer
519 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 ...
10
votes
2answers
22k 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), ...
1
vote
2answers
5k views

How to know if a background job is finished?

I invoke a script (do_something) in background via another script (do_manythings) as below. nohup do_something & How would I know in the parent script (do_manythings) that the job invoked ...
1
vote
4answers
206 views

How to set the process won't be terminated when the terminal stops

[Edit] Make it simple. I invoked java xxx... on Machine A using putty to connect from Machine B. However I cannot reach Machine B. How can I connect Machine A from Machine C to set the running ...
0
votes
1answer
44 views

How to resume a process from an SSH connection?

At work, I have lot's of interactive scripts running that I would like to access them later on from home. If I do Ctrl+Z to them and then bg, then I am able to use them from home using the fg command. ...
14
votes
4answers
9k views

How to kill a process with a single command?

I want to kill a process, after finding the id in a single step. I currently use these two commands: pidof <name> kill <#number_which_is_result_of_command> How can I write a single ...
1
vote
1answer
42 views

setpgrp causes tty gone

When using setpgrp vi (and other tty programs) work completely different than if setpgrp is not used. Example: perl -MIPC::Open3 -e '$pid= open3("<&STDIN", ">&STDOUT", ...
6
votes
1answer
8k views

Elegantly get list of children processes

I would like to get a list of all the processes whose parent is $pid. This is the simplest way I've come up with: pstree -p $pid | tr "\n" " " |sed "s/[^0-9]/ /g" |sed "s/\s\s*/ /g" Is there any ...
0
votes
3answers
38 views

processes started in this session

I've opened a terminal session and started some processes with &. When I tried closing the terminal window, it warned me that there were still jobs running in the background. I can see the ...
2
votes
1answer
8k views

How to check which process is using most memory

When I check free in one of Prod server it showing 70% of memory is being used: total used free shared buffers cached Mem: 164923172 141171860 23751312 ...
0
votes
1answer
90 views

Portable way to kill a process listening on a given port

Is there a way to kill a process listening on a given port (e.g. in bash lsof -t -i tcp:8000 | xargs kill) from a shell script that will also work on cygwin, as well as bash?
1
vote
1answer
89 views

How to start (or find) a process with RUID different from EUID?

Inspired by one of the previously answered questions, I tried executing a program by a user who was not its owner -- and the process's RUID and EUID remained the same. (Unless I read the answer wrong ...
0
votes
1answer
40 views

What is Dynamic interleave for process in Linux?

I have read through the source defined in /source/mm/mempolicy.c. Starting at line 1178: /* Do dynamic interleaving for a process */ static unsigned interleave_nodes(struct mempolicy *policy) { ...
19
votes
7answers
8k views

Is there a way to limit the amount of memory a particular process can use in Unix?

I need to test a process for memory management. I do not have the source, so I need to do all the testing from the OS side. I want to be able to say something like limitmemory 400k -p <pid> ...
4
votes
1answer
77 views

CPU usage of file system operations not shown in top

I run the following command (which does ls for 10,000 times) in a Ubuntu Linux terminal and use the top command to monitor the CPU usage. While top shows the total CPU usage (line 2) is about 48% ...
1
vote
2answers
236 views

Spawn multiple processes with a single command

Is there a way to create say 10 instances of a process (for example yes) with a single command? $instantiate 10 yes
1
vote
0answers
242 views

Why does my redhat 5.11 system have so many ext4-dio-unwrit processes?

I have a redhat 5.11 system running, and it looks like there are 32 of these processes. What are they, and why are there so many of them?
4
votes
2answers
81 views

How to kill a bunch of jobs based on ps output?

Here is output from ps: $ ps aux | grep blob ubuntu 4286 0.0 0.1 34748 9592 ? S Jan14 0:00 /usr/bin/python /usr/local/bin/pynt start_blob_reader ubuntu 4287 0.0 0.1 34748 ...
1
vote
1answer
44 views

process id and command

I want to write the process id and command of all processes with some name and from some user (for example root and init). What should I do? ps -f -u root -C init or ps -f -U root -C init ...
2
votes
2answers
37 views

Replace screen process from within screen

I have configured my shell to exec screen when it starts, unless it's already running within a screen session. So in a TTY, the process tree will look like something like this: ...
7
votes
5answers
5k views

How do I start a process with a nice value of -20 and not give it root privilege?

I would like to start a process with a nice value of -20. This requires me to use a command like - sudo nice -n -20 matlab. However, this starts matlab as root too. Is there a way to have matlab as ...
29
votes
7answers
7k views

Block network access of a process?

Is it possible to block the (outgoing) network access of a single process?
35
votes
5answers
100k 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. ...
2
votes
1answer
77 views

Traverse the Process Tree

I am aware that processes are organized in the form of a hierarchy. So, if I want to implement an operation which is to determine whether a given process belongs to a given sub-tree in the hierarchy ...
0
votes
2answers
64 views

Best way to kill processes in a list

I've got this zsh script. Is there a more a graceful way to do this? export PROCESSES_TO_QUIT='puma rake sidekiq spring rails ruby-debug phantomjs zeus passenger guard resque "node server.js"' pgr() ...
3
votes
1answer
161 views

Command for killing specific PID provided by previous command

Sometimes I need to kill a process (the reasons why are not important). And I know I can find that process with the following command: lsof -i :8080, being my candidate the last process in the output ...
27
votes
3answers
48k 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 ...
1
vote
2answers
2k views

How do I run two ongoing processes at once in linux/bash?

I would like to know how I can run two ongoing processes at the same time in Linux/bash. basically, I have a Node web server, and a MJPG-Streamer server. I want to run both these processes at once, ...
2
votes
2answers
1k views

How to track file change

nsswitch.conf file always corrupts somehow. I do restore from my backup every time it corrupt. When this file corrupts, its time stamp is changing. Now I wonder if there is a way to track that file ? ...
43
votes
6answers
66k views

How to monitor CPU/memory usage of a single process?

I would like to monitor one process's memory / cpu usage in real time. Similar to top but targeted at only one process, preferably with a history graph of some sort.
5
votes
2answers
137 views

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 ...
2
votes
1answer
2k 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
66 views

Unrealistically long process times displayed in top

I (partly) manage a small cluster and we are having some problems on a few nodes (running CentOS 6.4). Some processes show exceptionally long run-times in 'top', even though the computer has been ...
0
votes
1answer
75 views

I kill process but come back

I have a big problem on centos 6.4 i kill this(8904) but he come back and use the processor. How can we solve? I don't use apache(httpd) on my server. apache don't installed on machine. it's a ...
2
votes
1answer
72 views

Thin LVM pool frozen due to lack of free space, what to do?

My thin LVM pool got full and some programs hung: device-mapper: thin: 253:4: reached low water mark, sending event. device-mapper: thin: 253:4: no free space available. INFO: task jbd2/dm-6-8:742 ...
1
vote
0answers
24 views

How to get stdout of process? [duplicate]

I started a process from the command line, but the window server died. However I see the process I started is still running. Is it possible to connect a terminal to the process to see its output? ...