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

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most minimum processes required to have Linux that functions properly [duplicate]

If I want to have Linux that functions properly for a user, are the most minimum processes required are init/systemd, terminal emulator and shell?
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My compiled program is being run via init.d but eventually gets killed

I made a small utility application in C that monitors udev for power events and adjusts my laptop backlight brightness automatically. (I'm running Ubuntu 15.04) I ran the following commands and it ...
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Detect which program is blocked by firewall

The linux firewall can show a lot of information in the LOG target, for example via --log-uid. How can the executable doing the network call be logged, too? I did not find anything in the FAQ, the ...
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1k views

List process by name excluding grep [duplicate]

I am trying to list all the ffmpeg processes that are currently running on Debian machine (Ubuntu 15). I use the following command: ps aux | grep 'ffmpeg' If only one ffmpeg process is running, I ...
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Alternating a long running task to pause/run to reduce cpu

I have large file I need to mv and even with nice -n19 it seems to affect the server performance. I think an option would be to run the process in "chunks" whereby I run the command for a few seconds,...
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Make a process unkillable on Linux

I'm working on a password manager application, and for security reasons I want to launch an unkillable process. And besides I don't want this program to be a daemon since I need to read from standard ...
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2answers
186 views

Why do multiple instances of Mate-terminal have the same PID?

I've noticed, that all mate-terminal instances I start, be it inside a mate-terminal or via a link button, have the same PID. For example, I got something like $ wmctrl -lp <omitted lines that ...
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857 views

How does getpid work?

The getpid system call returns the process id of the invoking process. How does the kernel figure out which process is invoking the system call ?
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290 views

Shared library mappings in /proc/pid/maps

Why does /proc/pid/maps contain a few records for the same library ? Here is an example: 7fae7db9f000-7fae7dc8f000 r-xp 00000000 08:05 536861 /usr/lib/x86_64-linux-gnu/libstdc++....
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62 views

How to run bunch of hierarchical dummy shell processes (process of another process, etc.)?

I would like to run multiple processes where each process is running another one, so it will create a long process branch. I've tried: $ bash -c '(bash -c "sleep 20"); sleep 20' & $ pstree $(...
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795 views

How does a shell execute a program?

If I compile a program using gcc, and try to execute it from the bash shell, what is the exact sequence of steps followed by bash to execute it ? I know fork(), execve(), loader, dynamic linker (and ...
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146 views

Outputting PID of Rails server(s) with ps aux | grep - breaks when put into an alias?

I'm trying to create an alias for an unwieldy command I'm using to output the PID and some other information about two rails servers I have running. When I simply run the command in terminal (over ...
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48 views

Which tool can be used to configure the CPU priority of a process?

I know that you can use nice to re assign priorities of processes but which tool can be used to configure the CPU priority of a process ?
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474 views

What is /proc/<pid>/net/dev?

I'm interested in per-process network I/O counters, like those in /proc/net/dev and found what I thought was it under /proc/<pid>, i.e. /proc/<pid>/net/dev. But it seems that was too easy ...
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240 views

Memory usage of a given process (using Linux proc filesystem)

I want to know which files from /proc directory and which fields of these files I need to calculate the memory usage of a given pid. I've been using the "stat" file and the "vsize" parameter that is ...
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136 views

Allow a single process to access a file

If I am the owner of a file, then is there a way I can give another process (running under another user that doesn't have read/write permission to that file) permission to access it? I want only that ...
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116 views

Are blocked and blocked/suspend processes put into the same queue?

In a 7-state process model (new, ready, blocked, running, blocked/suspend, blocked/ready, exit), are processes in the blocked and blocked/suspend states for each event that processes are blocked on ...
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236 views

How do see the memory used by a program in ubuntu?

How can I see the raw memory data used by an application ? Like , suppose I have a file name something.sh . Now I run the command ./something.sh , and then I want see all the data its accessing in ram ...
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66 views

What module in the kernel that inform the DHCP client to start DHCP negotiation?

DHCP client is a process instead of kernel code. How the DHCP client know when to start sending DHCP discover message? Is it the IP module in the kernel that inform the DHCP client?
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150 views

defunct process - is it always a child process?

reading on what is a defunct process says that it is a child process which when it terminates/end is not properly handled/killed by its parent. but viewing on the below output servera> ps -ef | ...
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42 views

Restrict a process to accessing only a specific directory

How could I run a process dostuff such that it can only access files/folders in the directory somedir?
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3answers
219 views

What is the output of “du” command during a long copy?

Recently, I launched the cp command to create a backup of a big directory. So, I used a command like this: cp -rv big_directory new_location Because the files are big, it took a long time to ...
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48 views

Which process group does my program belong to when started from bash?

If I run a program from bash, then does my program belong to the same process group as the shell, or does it belong to a new process group? As I am making a shell in C, I need to handle the SIGINT ...
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124 views

Killing a comet zombie

I have a zombie process that is changing its PID, which is increasing. Is it possible to kill a process with PID greater than N?
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160 views

Killing PGIDs but proceses are respawning, how do I make it persistent?

I ran ps aux --forest -j to see parent and child processes. Here is an example: root 3744 3744 3744 0.0 0.2 77084 4160 ? Ss 09:34 0:00 /usr/sbin/cupsd -f lp 3747 3747 ...
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95 views

Is it better/preferred to kill all child processes by using PPID or PGID?

I need the ability to kill all child processes running under a particular parent. What would be the better option to do this? Using PPID or PGID? Something like this: pkill -TERM -P Would kill ...
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1k views

Why I can not use all the 100% potential of CPU?

I am using my computer clusters to run a MD C program but I can not use full potential of those clusters. But the this node have 16 CPUs and I also only give 15 jobs for those CPUs. But I can not ...
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Restrict a user from viewing other user's processes [duplicate]

Suppose there are two users : user1 & user2. Now we know that if I give top -u user1, I can see only the process respective to user1. But if I do top -u user2, I can see all the process running ...
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93 views

How to get PPID with PS using BSD options

I'm looking for a ps string that will give me all the output headers of "ps aux" but with the PPID. So far, I can only get the PPID column using ps -ef. I have tried numerous combinations but have ...
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Who forks the processes of piped commands in the shell?

Consider this command in the shell : ls|less Now we know that ls and less are run as two different processes. We know that the shell forks and creates a child process which load the ls program using ...
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72 views

How to start two processes piggie-backed? So the first finishes when the second finishes?

I'm running a script with ssh commands to a server behind a jump-host. Each time I want to run a command on my server in the secure network, I need to ssh into the jump-host (bastion) server and run ...
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350 views

Process which locks up, ignores SIGKILL, is runnable (not a zombie or in uninterruptable sleep). What state is it in?

I have a process which several times now has stopped responding and appears to be completely locking up. It doesn't respond to any attempt at strace or peeking with gdb (gdb just hangs on a wait4() ...
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Start a process from (noninteractive) shell script (cgi) and keep it running when script ends

I want a cgi script to start a process which stays alive after the cgi script exits. I tried: #!/bin/bash nohup process-to-keep-running & That works fine, if I run the script from an ...
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326 views

How to switch to other users's process?

A user has started a Java program and is currently running. As root, I can see it through ps -A. How can I bring this process to foreground?
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41 views

Open ports with no associated PIDs

I have some open ports on my laptop but netstat is not reporting which PID/Program is associated with them: $ netstat -tulpn (Not all processes could be identified, non-owned process info will not ...
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3k views

Linux ps -elf command output, what is Process Flag meaning?

In output of ps -elf command in linux, we can recognize that process flag of 4 and 1, and process flag of 5, (sum of 1 and 4), but what is meaning of process flag 0 ? unfortunately, man does not help ...
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Directory in /proc that isn't process dir but start with number?

Quick question. Is it possible to create directory in /proc that starts with number but isn't process directory (where name is PID)? I write software that searches for process directories and I wonder ...
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215 views

What does p and e denote in exec family of calls?

l and v in exec calls denote whether the arguments are provided via list or array(vector). I read it somewhere that p denotes the user's path and e denote the environment but did not understand what ...
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45 views

Restricting CPU time of processes by executable path

Is there a way to restrict CPU time (duration) for all processes which are invoked by executables that are located in a certain directory? I would like to be able to auto-kill all applications which ...
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3answers
305 views

What does it mean to run a process in background? [duplicate]

What exactly does it mean to run a process in the background? The difference between $program and $program&: Is it just that the input file descriptor is not inherited from the shell or is there ...
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667 views

Zombies in bash

Bash doesn't seem to create zombies. It looks like the processes get immediately reaped when they get killed. Can I make bash make zombies? Why I'm asking: I'd like to be able to safely kill a ...
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614 views

foolproof way to detect if java process is running

I have a java process that runs continually that sometimes, for reasons I have yet to fully debug, craps out. So, I also have a cron job that looks for the process every 5 minutes and if it finds the ...
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1answer
156 views

Resource (CPU time and memory) limitation and termination of a process upon violation in Linux

The problem: Given a process, limit the resources it and its child-processes can use. I.e. set CPU time and virtual memory quotas. When the process group exceeds one of the limits, terminate it, ...
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Is it possible to add a process to the job list in bash (e.g. to reverse “disown”)?

If I disown a job in bash and change my mind, can I undo it somehow ? If so, taking it further, is it possible to bring an arbitrary process under job control (an acceptable restriction would be that ...
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1answer
187 views

What is the actual process name when nautilus is copying files?

I am copying some files from an external drive to my desktop running Ubuntu. I can see the "File Operations" dialog which shows copying process. How do I find this particular process in ps aux | grep ...
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631 views

How can I know thread names that run on specific core

I am working in Java code. My code makes specific Java threads run on specific cores. In this code, I give names to Java threads. I need a Linux command that enables me to know the threads' names that ...
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196 views

How to kill a task that cannot be killed (uninterruptable?)

I have a task running that blocks pm-hibernate (on Linux 4.0.7-2). When I try pm-hibernate there is an error message "Freezing of tasks failed after 20.002 seconds (1 tasks refusing to freeze, ...
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243 views

Why can the waitpid system call only be used with child processes?

The man page wait(2) states that the waitpid system call returns the ECHILD error if the specified process is not a child of the calling process. Why is this? Would waiting on a non-child process ...
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How do I kill a process after detaching it from bash?

I have multiple scripts that detach a process from bash using nohup and &>/dev/null &. My question is, how do I kill the process after completely detaching it from bash. using killall or ...
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60 views

Process command

When I used ps -u root command in Ubuntu it showed the following output? PID TTY TIME CMD 1 ? 00:00:02 init 2 ? 00:00:00 kthreadd 3 ? 00:00:00 ksoftirqd/0 5 ? ...