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

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Strange cpu usage values reported by pidstat

I have a script that reports the cpu usage of a specific program reading values from pidstat. The script launches as: pidstat -C ^frontend$ -h -l -p ALL 1 1 The values reported this way sometimes ...
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How do I execute in background / return early?

For reference, I'm using phpseclib to control a remote SSH server using the 'root' account. I have to start/stop a java process which is ran in the background. Stopping works fine with killall java ...
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2k views

Getting pid of bash script from itself

I have a bash script with doing lot of things called script.sh: #!/bin/bash #It #Is #Doing #Things Is there a way that I be able to get the proccess of script and then kill it after 5 minutes? ...
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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 ...
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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?
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Finding the PID of the process using a specific port?

I am installing hadoop on my Ubuntu system. When I start it, it reports that port 9000 is busy. I used netstat -nlp|grep 9000 to see if such a port exists and I got this: tcp 0 0 ...
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824 views

Killing an instance of a process

This is an output from pstree In the picture you can see the marked boxes in which the processes are multiplied by a number? What is this number? I had a doubt that it is the number of instances ...
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4k 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 ...
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376 views

$BASHPID And $$ differ in some cases

I'm reading "BASH pocket guide of Oreilly". It said: The process ID of the current Bash process. In some cases, this can differ from $$. Above explanation , explained $BASHPID variable. ...
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1k views

Run a process to particular/dedicated pid only

I have a c program executable or shell script which I want to run very often. If I want to stop/pause or to notify something I will send signal to that process. So every time I have to check the pid ...
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164 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 ...
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664 views

How do I execute a script later?

I need to compile gcc45 on my computer and that's a lengthy and resource-intensive process for my computer, so I'd prefer to have it do it while I sleep (at night). What's the closest thing to: $ ...
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8k views

How to kill a process which can't be killed without rebooting?

There are 5 processes which can't be killed by kill -9 $PID and executing cat /proc/$PID/cmdline will hang the current session. Maybe they're zombie processes. Executing ps -ef or htop will also hang ...
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301 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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1k views

How to run java process to be seen not as 'java…' in processes list?

Is it possible to run a Java process in Linux in a way that it could be seen in ps as some sort of alias? It would be easier to restart it when it is down.
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how to ensure a program is always running but without root access?

Currently I need to have a program running all the time, but when the server is rebooted I need to manually run the program. And sometimes I'm not available when that happens. I can't use a normal ...
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2answers
355 views

Kill a process that keeps restarting

What if 'kill -9' does not work? or How to kill a script which starts new processes? doesn't help me in anyway. I have a python script which starts automatically with another process id using ...
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1answer
84 views

Which process scheduling algorithm is used by Linux?

The Linux operating system switches between running processes to enable multi-tasking. What algorithm is used to determine when to suspend the execution of the currently running process and which ...
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1k views

Wait for background processes to finish with inverse match process ID

I'm looking to run a number of background processes in a loop, but only want to wait for all of those processes to finish, still allowing another background process to continue. After doing some ...
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231 views

What does the term static variable mean in unix speak?

From the section 2.7 of the book - The Linux programing Interface named Process memory layout : Data is defined as the static variables used by the program. What is the significance of the word ...
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768 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 ...
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3answers
2k views

How can I test if a program is running from within a script

Let's assume that another user started a bunzip process, and I have a script that I'd like to start running after that bunzip finishes. What's the best way to check from inside my script that the ...
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2answers
425 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 ...
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364 views

Alert when running process finishes

There are a few questions and answers on here with regard to being alerted when a process completes/exits(1, 2) – but these all assume that the user has issued said process themselves, and thus can ...
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2answers
249 views

How can I get the version of the pgrep & pkill commands?

I looked at the manpages and there is no -v or --version argument for pgrep or pkill. How can i get some info on the version? I'm asking because on my version of Ubuntu man pgrep is giving me a ...
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531 views

Process in user mode switch to kernel mode. Then the process will have root privileges?

According to http://www.linfo.org/kernel_mode.html in paragraph 7: When a user process runs a portion of the kernel code via a system call, the process temporarily becomes a kernel process and is ...
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78 views

Contents of stack area of a process

I've been going through some Unix text books and I can't have a clear picture on the contents of the stack area of the process. Can anyone please explain or point out some references?
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695 views

Where is the virtual memory stored on hard drive?

If a process wants to access a memory address that is not in physical memory, the OS outsources a page frame from physical memory to the hard drive for later use. Where on the hard drive is this data ...
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4k views

What does kill 0 do actually?

In the man page, it says: kill [ -s signal | -p ] [ -a ] [ -- ] pid ... pid... Specify the list of processes that kill should signal. Each pid can be one of five things: 0 All ...
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873 views

What is meant by stack in connection to a process?

From the book Advanced programming in the Unix environment I read the following line regarding threads in Unix like systems All the threads within a process share the same address space, file ...
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1answer
631 views

Which processes should I NOT strace?

I've created a little function for strace'ing a set of the current user's processes by name: function pstrace() { local pattern="$1"; shift; prefixDashP $(pgrep -U $(whoami) $pattern) | ...
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1answer
91 views

Different between `ulimit -e` and `renice`?

I would like to run a backup script in low CPU and disk I/O. Is there any different between this: #!/bin/bash ulimit -e 19 ionice -c3 -p $$ and this: #!/bin/bash ionice -c3 -p $$ renice -n 19 ...
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241 views

How to monitor the last PID assigned by the kernel?

To monitor process creation I'd like to periodically write the last PID assigned by the kernel to any process on the system (not just processes created by the PID-monitoring program) with a time stamp ...
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What after exec() in ls command. Is the parent process printing the output to the console or the child?

I have a simple doubt on execution of the command ls. As per my understanding from the research I have done on the internet, I understood the below points. When we type ls command shell interprets ...
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371 views

Please explain the -f option in pgrep

man pgrep says the following about -f option: -f The pattern is normally only matched against the process name. When -f is set, the full command line is used. What does it ...
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1answer
412 views

bash: disable new process PID message

It may look like this: [2] 2847. I guess the first digit is just an enumeration of processes created from the shell. The second is the PID. Anyway, I never care about that information so it is just ...
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596 views

How is FireFox running on a virtual machine that has no display?

I am using a Red Hat virtual machine, accessible only remotely. However when I use the top command, one of the displayed processes taking up the most memory is firefox, located at ...
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175 views

How to detect out-bound port from PID

I have several applications that run on random ports. How would I take the pid or the file location and find which port it is running on? Example of desired output: www-data/apache = 80 ...
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1answer
112 views

Is there a way to tell which file (script, specifically) executed a command?

I'm running Slackware 13.37, and I was wondering if there was a way to tell which script executed a command. I tracked the process and its arguments, but I would like to know where the command ...
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How to list only non-<defunct> processes?

Is there a combination of command-line options for ps or pgrep or some other relatively direct way to determine if a particular process name is actually running (available for normal use).. By ...
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Discovering the number of running and blocked processes in Mac OS X

In Linux, I could discover the number of running and blocked processes running grep "procs_running" /proc/stat and grep "procs_blocked" /proc/stat Is there a way to do it in Mac OS X? ...
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97 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 ...
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1answer
344 views

per process private file system mount points

I was checking unshare command and according to it's man page, unshare - run program with some namespaces unshared from parent I also see there is a type of namespace listed as, mount ...
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1answer
1k views

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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1answer
192 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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2answers
105 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 ...
3
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1answer
363 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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482 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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99 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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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 ...