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

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18
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5answers
23k 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.
11
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4answers
482 views

In bash, what are potential negative consequences of pausing a process with control-z?

Using bash, one can pause a process with control-z. However, are there any general circumstances or guidelines to beware of where a process would not behave well with being paused? My specific ...
2
votes
2answers
348 views

Quick and dirty way to run a process more than once

I am looking for very simple bash script that would allow me to launch a process a few times. What's essential to me is that after the processes terminate, everything will clean up automatically. ...
1
vote
2answers
5k views

Kill all processes related to an application

I have two processes that are temporarily spawned and I need to kill them. Here are the processes from ps aux david 38329 0.0 5.0 3916476 104624 s002 S 11:33AM 0:17.43 /Applications/...
2
votes
2answers
2k views

How to pass data outside process for zenity progress?

Usually this would be a question about how to pass data from a subprocess to a main process, but maybe zenity has some extra quirks so please focus on zenity. Example: #!/bin/sh ( echo "10" ; sleep ...
5
votes
1answer
1k views

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 launched ...
1
vote
1answer
778 views

How to preload my .so everytime an application executes?

I've successfully used a hook under linux with this article: http://hackerboss.com/overriding-system-functions-for-fun-and-profit/ Now I want to make my .so file load every time espeak loads up. No ...
11
votes
1answer
5k views

Nice and child processes

Can someone tell me what is the relationship between a specified nice level and child processes? For example, if I have a default nice of 0, and I start a script with nice 5, which in turn starts ...
5
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2answers
550 views

Set process exclusivity in Linux

I am trying to measure the performance of a process. I have widely ranging performance measurements on small bit of single-threaded deterministic code that should perform the same every time. I would ...
3
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2answers
1k views

How to reload a background process?

I have a python script which I would like to run in the background. So I do this: $ nohup python script.py & If I am frequently making changes to the script, I need to terminate the process ...
4
votes
3answers
9k 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 ...
8
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2answers
5k 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?
0
votes
1answer
3k views

The TIME field in ps -ef

When I do ps -ef, I see "TIME" field. What does this field mean? From what I understand, this tells the actual CPU time, that the process got (amidst all the context switching). Does the TIME field ...
6
votes
2answers
18k views

How to see complete list of processes in top

When I do 'top', I learn that there are many processes running out of which many are in sleep state. I need to see complete snapshot of all processes at that point. the 'top' is able to show listing ...
16
votes
2answers
14k views

How to know reason of a process going to sleep state and wake it up?

When I do 'top' , I see my perl script process in 'S' state. Is there a way to know, what is making this perl process go in sleep state and ways to wake it up? Any way to debug to give more insights ...
0
votes
1answer
1k views

Need help with understanding output of ps -ef on linux

When I do ps -ef on my Linux box, I get: UID PID PPID C STIME TTY TIME CMD Please help me with meaning of C,TIME. is the TIME , the actual cpu time allocated to the process?
1
vote
1answer
168 views

How do you prevent user from opening a program?

I'm trying to write a script which prevents the concerned user from opening programs (mostly internet browsers) from being run during a certain time (like 1000 to 1200 hrs). This is like a ...
2
votes
1answer
330 views

What's the best strategy to catch mystery process?

I have running processes on my server that get killed every night at midnight. It's at work, I'm not around when it happens and I don't have remote access. The kill occurs very predicably at 23:59 ...
4
votes
3answers
1k views

Why is there a type for process ids (pid_t), but not for file descriptors (fd)?

I see that pid_t is typedef'd in unistd.h, and file descriptors are defined to be int in fcntl.h. But since they are used in similar ways, wouldn't it make sense to have a typedef for file descriptors?...
2
votes
1answer
219 views

Set a callback for when a certain process is spawned

The script I'm writing launches process A, which after an uncertain amount of time, launches a child process B. I need the script to execute a command C which depends on process B. But B might not be ...
5
votes
4answers
25k views

Kill all process of users in Ubuntu?

How to kill all process of one user? When I make ps aux I obtain a list of process with several users, and I want to kill all process of user name1 for example! What's a command to do that in Ubuntu?
29
votes
1answer
29k views

Need explanation on Resident Set Size/Virtual Size

I found that pidstat would be a good tool to monitor processes. I want to calculate the average memory usage of a particular process. Here is an example output: 02:34:36 PM PID minflt/s ...
4
votes
1answer
160 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 ...
1
vote
1answer
566 views

Process Migration Scripting

I want to write some shell script which can perform the process migration from one node to another. Is it possible ? Can somebody please help me scripting this. What all should I know before coding ...
5
votes
2answers
3k views

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 ...
3
votes
2answers
509 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. ...
4
votes
2answers
672 views

Force change of a user's cwd as root

I'm looking to change a user's process such that I can set it's cwd. Related, and secondary to the question, I have a filesystem I want to unmount but a user is sitting on it with a bash process. I ...
1
vote
1answer
1k views

How to kill a ghost process? AIX 6.1

oslevel: 6100-05-01-1016 according to topas: root 1769602 1 93 20 112 0 128 32498:07 87.1 0 0 ldmp_pro according to ps: -bash-4.1# ps -ef | egrep -i "1769602|ldmp" ...
12
votes
2answers
6k views

How is /proc/self implemented in Linux?

I was tinkering around with the /proc filesystem in Linux, and I came across /proc/self, which is a symbolic link to the process directory of the current process. I would like to know how it is ...
2
votes
1answer
2k views

How often is PSS value updated for a given process in /proc/pid/smaps

So if n processes are sharing a library L with size M then the contribution to their PSS is M/n. Now imagine one of the process terminates. So the contribution would be M/(n-1). Q1: My question is ...
2
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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 ? ...
6
votes
2answers
5k views

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 ...
2
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4answers
2k views

Is there a way to identify which process turns into Zombie process

One of the ubuntu server has 82 zombie processes. All processes shows '[sh] defunct' as process command. Is there a way to find out which process is becoming a zombie process? I tried checking the /...
1
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1answer
118 views

Command to list in real time all the actions of a process

I cannot remember this command (and googling was unsuccessful), but there is a way to get the list of actions performed by a process, that outputs something like # listprocessactions -p 1234 0....
31
votes
1answer
29k views

Getting information about a process' memory usage from /proc/pid/smaps

For a given process in /proc/<pid>/smaps, for a given mapping entry what are: Shared_Clean Shared_Dirty Private_Clean Private_Dirty Is Shared_Clean + Shared_Dirty the amount of memory that ...
6
votes
5answers
7k views

Graceful way to kill process

After my bash script is done with the selenium server, the script kills it like this: kill `ps -ef | grep selenium | awk '{ print $2 }'` While this works and it does kill the selenium script, it ...
8
votes
1answer
3k 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 ...
1
vote
1answer
2k views

How can I send data to the STDIN of a background process?

I'm trying to: Launch several ssh sessions (processes) through a script (Python) Communicate with the sessions by sending them commands via STDIN (even though they aren't open in my current terminal)...
2
votes
1answer
4k views

Apache cannot fork: cannot allocate memory

I am running apache on Fedora with mod_perl. The server forks a process to send an email frequently - and the fork exits. Suddenly, I got: Cannot fork: Cannot allocate memory. There was plenty of ...
2
votes
5answers
9k views

How to stop a program running as daemon

I have launched iperf in daemon mode with iperf -s -D and now I want to stop the service. I tried to use sudo kill pid but it neither work nor complain. The daemon is still running when I check ...
38
votes
4answers
45k views

How to attach terminal to detached process?

I have detached a process from my terminal, like this: $ process & That terminal is now long closed, but process is still running and I want to send some commands to that process's stdin. Is ...
1
vote
1answer
843 views

Cross-platform (Linux, BSD, Solaris) way to check if pid exists

I am looking for a reliable cross-platform way to check if a process with a specific pid is running. Two possible solutions came up: kill -0 $PID — exit status is 0 if it the process exists and 1 ...
10
votes
2answers
2k views

Are kernel threads really kernel processes?

I've read in many places that Linux creates a kernel thread for each user thread in a Java VM. (I see the term "kernel thread" used in two different ways: a thread created to do core OS work and a ...
5
votes
4answers
1k views

How does forking affect a process's memory layout?

Please see the following figure showing the memory layout of a process: : When someone forks(), and a new task_struct is assigned, what happens to the addresses of the process? In more or less other ...
5
votes
1answer
4k views

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 (...
33
votes
2answers
4k 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 ...
6
votes
1answer
377 views

Unkillable apache2 processes

After upgrading from debian lenny to squeeze (apache2 2.2.16-6+squeeze4 and php 5.3.10-1~dotdeb.1), my apache processes started to exit with segmentation fault. It happens every 5-30 minutes (for 1 ...
12
votes
3answers
872 views

Maintain 100 instances of a program running

I'm currently using supervisord to maintain 100 instances of a script running at once. If any die then it starts up a new one. However it seems to be struggling maintaining larger numbers (>300 ...
105
votes
4answers
105k views

How to get the pid of the last executed command in shell script?

I want to have a shell script like this: my-app & echo $my-app-pid But I do not know how the get the pid of the just executed command. I know I can just use the jobs -p my-app command to grep ...
3
votes
3answers
166 views

Detecting whether a server is loaded

I have to start some performance test on a Rhel 6 box, but before starting the test, i have to make sure there are no other java processes running. The manual way of doing it would be to use "ps -ef ...