Tagged Questions

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

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3
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0answers
66 views

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 ...
1
vote
3answers
76 views

Run linux process at very very low priority?

I have regular process that not so important but will consume so much CPU power, and I have another process which is really important, but it spend most of the time idle, but when it got a job it ...
0
votes
1answer
25 views

Background Process not running?

I ran a C program with an infinite while loop in a terminal and observed one of the CPU cores shot to 100% usage. When I turn it into a background process using Ctrl+z, the CPU usage suddenly dipped ...
2
votes
0answers
57 views

How to run the dialog command with proccess? [duplicate]

NOTE: Please look at my code, it's a Bash script. I want to display both dialogs on the screen at the same time, one dialog displays this: tail –f from - /var/log/proccess1.log and the second ...
2
votes
3answers
16 views

how to run the dialog command with proccess

Please look on my code – ( bash script ) I want to display both dialogs on the screen on the same time, one dialog display the: tail –f from - /var/log/proccess1.log , and the second dialog ...
1
vote
1answer
45 views

Deterministic method to find out whether some other process is in a chroot jail and where?

NOTE: I'm familiar with this U&L Q&A titled: How do I tell I'm running in a chroot? that sounds similar to what I'm asking, but there's a subtle difference to what I'm looking for. That ...
4
votes
1answer
43 views

How can process doing “vfork without exec” end up in a long uninterruptible sleep?

In this answer user suggests that Normally, Uninterruptible sleep should not last long, but as under windows, broken drivers or broken userpace programs (vfork without exec) can end up sleeping ...
1
vote
1answer
29 views

Empty kernel processes on CentOS vps : 2 different servers

I'm not sure I'm asking correctly, or perhaps I'm just looking at the wrong things. I'm migrating from one CentOS Vps (on an OpenVZ box) to another CentOS VPS (on a VMWare box). VPS #1 = CentOS ...
4
votes
1answer
70 views

How to completely detach a process

I want to spawn a process and run it at the top level so that when the shell exits, the process keeps running. I had mistakenly thought that nohup would do this, but when I exit from the shell (the ...
5
votes
2answers
302 views

Why does process substitution result in a file called /dev/fd/63 which is a pipe?

I am trying to understand named pipes in the context of this particular example. I type <(ls -l) in my terminal and get the output as, bash: /dev/fd/63: Permission denied. If I type cat <(ls ...
0
votes
1answer
126 views

Process ownership on linux changes to root when the user tries to kill the process [closed]

We have a bunch of RHEL machines which all run an application binary that is owned by root and has SUID set. Let's say user X starts the application, the process starts with PPID 1, since SUID is set ...
5
votes
1answer
111 views

Is the Unix process scheduler itself a process?

Is the Unix process scheduler itself a process, or does it piggyback on other processes in the same way a system call does (running kernel code in the user process with the kernel bit set)?
0
votes
1answer
49 views

Comparing Windows and Linux machine hardware

I have to compare Linux and Windows machine hardware? In windows system, I can open the My computer properties and see the details like processors, RAM Hard disks etc. Through task manager, I can see ...
9
votes
1answer
216 views

Why does the location of Enviroment Variables vary that much?

Reading the book Hacking: The Art of Exploitation by Jon Erickson, I am trying to approximate the address of an environment variable SHELLCODE to exploit a program. Every time I run ...
0
votes
2answers
48 views

Process auto starts itself not by cron

My linux server was hacked. and now there is a file in root directory that generates big traffic. when i kill this process it autostarts itself again. then i did chmod -x. but it returned x option. ...
1
vote
1answer
138 views

Real time processes scheduling in Linux

I have been learning some scheduling concepts. Currently my understanding so far is as below. There are real time processes and non real time processes. Non real time processes can have nice values ...
1
vote
1answer
55 views

How logical address of one process differs from the logical address of another?

I am a newbie. I am reading Understanding Linux Kernel. There, I am trying to understand how logical address got translated to physical address. To my understanding, I believe logical address got ...
2
votes
1answer
54 views

strace works for some builtin commands

I'm trying to understand some kernel level concepts in Linux. I was checking on the difference between shell builtin commands and the other executable commands. This wonderful answer clearly tells ...
2
votes
0answers
31 views

API Monitoring and Hooking

I am currently reading the "Malware Analyst's Cookbook and DVD". There is a chapter "Dynamic Analysis" and there are also some recipes about hooking and monitoring API calls of process but it is for ...
4
votes
1answer
44 views

Preserve evidence of intrusion / deleted executable?

If you are faced with a non-root remote command execution vulnerability, and there is a foreign executable that's running on your Linux system from a user with only non-administrator privileges, ...
2
votes
1answer
160 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 ...
3
votes
3answers
231 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 ...
5
votes
1answer
48 views

How disk IO priority is related with process priority?

I'm running software that overloads disk IO sometimes. I don't need fast response from that software, I need fast response from other applications, so I could set low process priority for that. I want ...
0
votes
1answer
36 views

Does “stopped” belong to “blocked” state?

The manpage of ps says PROCESS STATE CODES R running or runnable (on run queue) D uninterruptible sleep (usually IO) S interruptible sleep (waiting for an event to complete) Z ...
2
votes
1answer
204 views

why “ps -ef -u root -U root” also displays user processes?

ps -ef -u root -U root Also displays processes whose user is not root (the current user). Can someone explain me why ? -u : EUID -U : RUID
2
votes
2answers
79 views

cpulimit does not detect Node.JS process

I was able to limit python process to use only 50% CPU with the following cpulimit -l 50 -e python but when I tried to do the same for Node, and it is not able to detect the process at all. Does ...
0
votes
3answers
132 views

Is reparenting from the shell possible?

This question is closely related to How to "correctly" start an application from a shell but tries to tackle a more specific problem. How can I spawn an application from a shell and thereby ...
0
votes
2answers
38 views

Is killing processes created on startup safe?

I've just got a vserver running debian 7 and whenever I start the server and call the top command, there are very many processes that were started automatically on startup. Can I kill them or are ...
1
vote
1answer
61 views

Process status on AIX

I want to get process status on AIX like we get it on Linux from /proc/<PID>/stat, I did not find the status in /proc/<PID>/status file. There was some encrypted text there. Which file ...
0
votes
0answers
34 views

How is user space process/thread controlled by the operating system

I understand this: User code executes in a process/thread context in a process address space, in user mode, and can address only user code/data defined for the process, with no access to privileged ...
2
votes
2answers
307 views

find out the memory allocated for a particular process in ubuntu

Could anyone please tell me how to find out the memory allocated for a particular process in ubuntu?
3
votes
1answer
32 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 ...
0
votes
2answers
152 views

How to kill a process running in specific script

I have two script files running simultaneously. I just need to kill the java process running in one script without affecting the java process in the another one.
2
votes
1answer
46 views

Process IDs range

On GNU/Linux system I seen only positive PIDs, but when kernel panic occured I seen info about process with PID=0. What's it? On Minix 3 I seen processes with negative PIDs. Minix is POSIX-compatible ...
1
vote
4answers
97 views

Prevent a second instance of my software from starting

I wrote a service script to run a specific software at boot time. How can I restrict this software so that it does not run manually again? I mean software has to have just one instance in the ...
0
votes
0answers
34 views

How to start Process state

Over and over and also aver again. I saw this picture on operation system text book. But this time, I want to see the codes to understand this picture more tangible. where is codes which their duty ...
1
vote
3answers
123 views

How can I get the pid of a process started this way

#!/bin/bash mkfifo /var/run/out while true do cat /var/run/out | nc -l 8080 > >( while read line do do some stuff done ) done How can I get the pid ...
2
votes
1answer
167 views

Where is PCB on linux

A PCB is a process control block , this is its definition on Wikipedia Process Control Block (PCB, also called Task Controlling Block,[1] Task Struct, or Switchframe) is a data structure in ...
1
vote
1answer
279 views

How can I kill child processes with start-stop-daemon?

I'm writing a simple web server using nc and bash. It looks like this: #!/bin/bash rm -f /var/run/streamman/out mkfifo /var/run/streamman/out trap "rm -f /var/run/streamman/out" EXIT while true do ...
1
vote
2answers
108 views

kill xterm process in a bash

I would like to kill the xterm process I started this way in a script: #!/bin/bash echo "#!/bin/bash" > /tmp/test0 grep file | awk '{print "xterm -hold -e echo",$1,"sleep 10" && pid=$!}' ...
9
votes
4answers
2k views

Why is SIGINT not propagated to childs process when sent to it's parent process?

Given a shell process (e.g. sh) and it's child process (e.g. cat), how to simulate the behavior of CTRL+C using the shell's process ID? This is what I've tried: Running sh and then cat: ...
0
votes
1answer
555 views

Are lock, mutex, and semaphore for between threads or between processes?

I think lock, mutex, semaphore are used for synchronized multiple (threads or processes?) to access something simultaneously. Must this "something" be some shared memory between multiple (threads or ...
3
votes
3answers
163 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?
5
votes
1answer
254 views

Get CPU usage for single process

I've got a problem getting a real-time CPU usage of a single process (by its PID). I'd like to setup a watchdog for the CPU usage of a process because it's suddenly reaching 100% of the CPU usage ...
0
votes
2answers
36 views

moving a process to fg and bg [duplicate]

Suppose I run a process in the background likw ./script &, I can bring it to foreground by running fg. However, is there a way to move it back to background without stopping it (as in ctrl+z) or ...
0
votes
1answer
258 views

Restarting process via cron every 12 hours

I'm not familiar with cron at all, and I've looked it up and am still confused as to how specifically it works. I'm on CentOS 6.5, and I need to end a process and then start it again every 12 hours. ...
1
vote
2answers
76 views

Remove unneeded file lock in script

I have some script using flock executable. It works well. Problem is when this script calls another script, and it creates background process. In this situation background process inherits file locked ...
0
votes
1answer
75 views

Emacs windows, frames, server and clients: threads or processes?

From http://www.gnu.org/software/emacs/tour/ Emacs server Some people like to keep only a single instance of Emacs open and edit all their files in there. Doing this has a few advantages: ...
1
vote
2answers
59 views

Call background process back to stdout

Is it possible to "call" a background process output to be shown in the terminal? Example: cron starts apt-get to update the system and I want to see the output of apt-get
2
votes
1answer
462 views

I can't install new packages and can't update and upgrade

I'm trying to install some program on Ubuntu, but when I try it I got the following error.- E: Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable) E: Unable to lock ...