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

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Bash way to check if a process is already running in the background (and skip re-execution based on that)?

Can I make a bash command line that only runs a certain command if the process is not already running (in the background)? How do I check*, if a command is already running? (so I can add the next ...
1
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1answer
21 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 ...
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3answers
81 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 ...
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4answers
59 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
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0answers
25 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 ...
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1answer
41 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 ...
2
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1answer
31 views

where is PCB on linux

PCB is process control black , this is its definitions on Wikipedia Process Control Block (PCB, also called Task Controlling Block,[1] Task Struct, or Switchframe) is a data structure in the ...
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2answers
874 views

Discrepancy between reported used memory and sum of application memory usage

I'm running a desktop system that quite regularly suffers from lack of memory, this prompted me to investigate what causes the issue in the first place. Problem is, there's no single process that ...
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2answers
33 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",$1,"sleep 10" && pid=$!}' ...
6
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3answers
3k views

killall gives me `no process found ` but ps

Could somebody explain to me the difference between kill and killall? Why doesn't killall see what ps shows? # ps aux |grep db2 root 1123 0.0 0.8 841300 33956 pts/1 Sl 11:48 0:00 ...
2
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2answers
87 views

Detecting kernel thread on pre-3.0 kernels

Looking at the proc man page (http://man7.org/linux/man-pages/man5/proc.5.html) it is possible to detect which processes are kernel threads in /proc/<pid>/stat by looking at the flags value ...
6
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4answers
299 views

Send SIGINT to child process of shell, simulating CTRL+C (Linux)

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
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1answer
45 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
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3answers
45 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?
4
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1answer
41 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 ...
5
votes
2answers
2k views

How do I tell a script to wait for a process to start accepting requests on a port?

I need a command that will wait for a process to start accepting requests on a specific port. Is there something in linux that does that? while (checkAlive -host localhost -port 13000 == false) ...
0
votes
2answers
25 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
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1answer
27 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. ...
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0answers
6 views

What does the following code do? [migrated]

Including the initial parent process, how many processes are created by the program: #include <stdio.h> #include <unistd.h> int main() { /* fork a child process */ fork(); ...
0
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1answer
35 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: ...
70
votes
6answers
38k views

How can I close a terminal without killing the command running in it?

Sometimes I want to start a process and forget about it. If I start it from the command line, like this: redshift I can't close the terminal, or it will kill the process. Can I run a command in ...
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2answers
35 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 ...
2
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1answer
7k views

How to find Heap memory of a running process? [duplicate]

I would like to know how to find the heap memory of a process that is running in the background. Is there any command that allows such?
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1answer
253 views

List of killed processes HP-UX

Is there a file similar to the one in this answer http://unix.stackexchange.com/a/10078/5027 to determine the processes which were killed, in a certain time, for example, yesterday, in HP-UX?
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2answers
37 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
4
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2answers
36 views

Is it possible to force a group member to run something allowed by sudoers as himself only?

The sudoers line is %game_servers ALL= NOPASSWD:/usr/bin/renice which allows group members renice any process run by any user without pw, but I'd like to allow group members renice their own ...
2
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1answer
41 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 ...
0
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1answer
19 views

How to add a progress bar to cryptsetup luksFormat?

Example command. cryptsetup --hash sha512 -c aes-xts-plain64 --key-size 512 luksFormat /dev/loop0 This can take quite a while for big files / on slow disks. How to add a progress bar?
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1answer
23 views

What do brackets mean in the output of pstree?

What are the differences between [] and {} and [{}] used to enclose a process in the output of pstree? I guess [] is used for specifying more than one processes. For example, ...
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0answers
22 views

How do you adjust other user's job priority?

Let's say your coworker started a very intense process and went home. It's occupying most of the CPU resources, and you can't do your stuffs because of it. If it was your own process, you could run ...
0
votes
1answer
13 views

/usr/bin/X :0 -audit process

Hello I am trying to solve some internet problems that I have. It is a university computer and I do not have root access. I want to understand what is this processor, that root has started, and if you ...
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0answers
59 views

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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2answers
3k views

ATOP shows red line vmcom and vmlim. What does it mean?

utility atop shows: ATOP - MyServer 2013/01/07 00:03:57 10 seconds elapsed PRC | sys 2.18s | user 8.33s | #proc 141 | #zombie 0 | #exit 0 | CPU | sys 21% | ...
5
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2answers
233 views

How to determine what instructions a process is executing?

I know about strace and ltrace, but that only tells me what system calls and library calls a process is executing, respectively. I would like to know exactly what instructions a process is executing. ...
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1answer
54 views

How to kill - softly? [duplicate]

If I want to kill a process as careful and politely as possible, which signals should I use in a kill command, in which order? I would like to give the programm any kind of time to clean up, if it ...
2
votes
1answer
498 views

What is the difference in CPU utilization between 'ps aux' and 'ps -ef'?

I use Ubuntu 12.04.1 Linux. I see a difference between %CPU and C output format of ps command for a process. It is not clearly noted in the ps man page. Man pages says: CODE HEADER ...
3
votes
1answer
48 views

Process history in Unix/Linux systems

I know that ps -efl shows running processes on *nix systems. I would like to check history of the (past) processes that have been run on a particular machine, preferably with all the information ps ...
70
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2answers
5k views

How does Linux “kill” a process?

It often baffles me that, although I have been working professionally with computers for several decades and Linux for a decade, I actually treat most of the OS' functionality as a black box, not ...
0
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1answer
26 views

Loginuid, should be allowed to change or not (mutable or not)?

I am trying to configure the linux kernel. I was confused by Make audit loginuid immutable (AUDIT_LOGINUID_IMMUTABLE) [N/y/?]. The help says: +config AUDIT_LOGINUID_IMMUTABLE + bool "Make ...
3
votes
1answer
39 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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4answers
6k 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? ...
5
votes
2answers
47 views

How can I see i/o stats for a briefly running process?

For long running processes like init, I can do things like $ cat /proc/[pid]/io What can I do if I want to see stats for a briefly running process such as a command line utility like ls? I don't ...
14
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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?
0
votes
2answers
33 views

Using /proc/stat for the number of processes running on the system

How does one find out the true number of processes that is running on your system. A number of articles mention using ps in order to count the number of processes. But recently I looked at cat ...
22
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5answers
12k views

Determine which process is creating a file

Given file path, how can I determine which process creates it (and/or reads/writes to it)?
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5answers
32k views

Is there a way to see details of all the threads that a process has in Linux?

For Windows, I think Process Explorer shows you all the threads under a process. Is there a similar command line utility for Linux that can show me details about all the threads a particular process ...
2
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0answers
32 views

Why are the process priorities not respected?

I was running four jobs in the background with HTCondor. It sets the priority to 10. Then I was compiling something with make -j4 in the foreground (priority 0). However, the HTCondor jobs still got ...
2
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1answer
42 views

The current path of a process

Suppose I write a program, which outputs a file under a relative path (as opposed to a full/absolute path) - let's say, the current path. Then I compile it and store the executable under some dir ...
4
votes
1answer
82 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 ...
12
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3answers
15k 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 ...