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

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Elegantly get list of children processes

I would like to get a list of all the processes whose parent is $pid. This is the simplest way I've come up with: pstree -p $pid | tr "\n" " " |sed "s/[^0-9]/ /g" |sed "s/\s\s*/ /g" Is there any ...
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What is “automatic stack expansion”?

getrlimit(2) has the following definition in the man pages: RLIMIT_AS The maximum size of the process's virtual memory (address space) in bytes. This limit affects calls to brk(2), mmap(2) and ...
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Can I add to my groups in the current (shell) process? [duplicate]

If I add myself to a group, it applies only to newly launched processes. Actually it's more restricted than that; it seems to apply only to new logins. I'm not sure what the exact mechanism is, but ...
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Getting disk i/o statistics for single process in Linux

I need to monitor the I/O statistics of a process that writes to disk. The purpose is to avoid write rates too high for long periods. I know there's iostat tool to accomplish this task on a ...
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Process descendants

I'm trying to build a process container. The container will trigger other programs. For example - a bash script that launches running background tasks with '&' usage. The important feature I'm ...
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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)?
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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 ...
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Bash script wait for processes and get return code

I am trying to create a script which will start many background command. For each background command I need to get the return code. I have been trying the following script : #!/bin/bash set -x ...
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when does the system send a SIGTERM to a process?

My server program received a SIGTERM and stopped (with exit code 0). I am surprised by this, as I am pretty sure that there was plenty of memory for it. Under what conditions does linux (busybox) send ...
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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 ...
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453 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 ...
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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 ...
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How can I search/browse in some process's memory?

I'm using MacOS X 10.7 and I'm not very familiar with unix. Is there a command for a search in some process's memory for a string?
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File descriptor limits are lost after a system reboot

I'm trying to increase the default file descriptor limits for processes on my system. Specifically I'm trying to get the limits to apply to the Condor daemon and its sub-processes when the machine ...
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197 views

How to monitor top applications using CPU (and IO if possible) in a graph?

I need to find what and when these applications used so much CPU (and IO if possible too). This should be in a graphic timeline like we see in GNOME System Monitor CPU History. I also want to compare ...
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529 views

Suggestions needed to debug why ps -ef gets stuck

A few of my processes consume 100% cpu. I'm trying to figure out which scripts are causing it I tried running strace ps -ef: open("/proc/PID/status", O_RDONLY) = 6 read(6, "Name:\textract\nState:\tR ...
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Hide processes from other users based on groups (under Linux)?

Is it possible to configure process hiding for certain user groups under a linux system? For example: Users from group X should not see processes owned by users from group Y in ps/top or under /proc. ...
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Detailed Per-Process Profiling

I am looking for a way to profile a single process including time spent for CPU, I/O, memory usage over time and optionally system calls. I already know callgrind offering some basic profiling ...
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687 views

What is the need of the struct thread_info in locating struct task_struct?

While reading through the Linux Device Drivers, I could understand that the Process Descriptor (of type struct task_struct) has all the info regarding a particular task. The process descriptors are ...
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How to kill two or more processes with one kill command?

I am using the following command to kill one java process via shell script: pidof java|xargs kill -9 $1 What if the list of pidof output has more than one elements? How do I kill them both with ...
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419 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 ...
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Slow down a process without affecting other processes

I have a program. When it is running, the CPU temperature raise from 50 to 80 Celcius, which is my major concern. I can control the CPU frequency to slow it down, but other processes will be slowed ...
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How do I get a mapping of Pid to Port?

I have a process which I need to run on a specific port. I have started some other process on that port and I need to kill it. Unfortunately, I don't remember the name/pid of the other process so I ...
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How to pkill by “command name”?

So I'm executing a command like: COMMANDNAME -PARAMETERS But..why can't I kill it with "pkill"? I'm trying with: pkill -9 "COMMANDNAME -PARAMETERS" but it doesn't kills the "COMMANDNAME ...
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What happens to suspended jobs in unix?

We can issue CTRL+Z to suspend any jobs in Unix and then later on bring them back to life using fg or bg. I want to understand what happens to those jobs that are suspended like this ? Are they ...
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How to check how long a process ran after it finished?

Currently I'm using the following to check how long a process is actually running: ps -eo uid,pid,etime | egrep '^ *MY_ID' | egrep 'PID_OF_PROCESS' And that outputs the following: MY_ID ...
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What call before a fork?

A long while ago I went to a job interview with a thoroughly weird company in London who claimed to be expert Unix consultants. Anyway these people were complete nutters and not surprisingly the ...
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Check for Process if Same is Running

Is there a script or a way in linux that when I try to execute a shell script/process, if the same is running, it will prompt that same is running and will exit otherwise it will continue.
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Single instance of script, but only with same arguments

I have this beautiful little code here that will exit from a script if there's another instance of it running: single_instance(){ if pidof -x "${0##*/}" -o %PPID >/dev/null; then exit ...
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“Virtual” shell, ie. jailing an user inside a process after the (SSH) login

The title might not say much about the issue at hand so let me get straight to the point. Let's assume I have a casual user who can log in to the system via SSH into a bash shell. I also have a PHP ...
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656 views

What is a subshell (in the context of the documentation of make)?

I'm reading a book about the make command and there is a paragraph: If any of the prerequisites has an associated rule, make attempts to update those first. Next, the target file is considered. ...
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why new pid is smaller than the old ones?

Is there any chance the new process's pid is smaller than the existed ones ? I have a daemon process which will restart when be killed, I recorded the pids, and found that the pid first came smaller, ...
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How to find which Process is causing High CPU usage

Is there any way to find out from terminal which process is causing high CPU Usage ? It would also be useful to order processes in descending order of cpu Usage
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Possible to get SMS/text message notification when process ends/is killed?

There are scripts that will send an e-mail when a server process is finished. However, I do not want to check my email every so often just to see whether a job has finished. Therefore I'd like to get ...
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Terminating a bash shell script running in the background

I often use bash shell scripts to run simple commands for many different files. For example, suppose that I have the following bash shell script, called script.sh, that runs the program/command foo ...
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Is grandchild process also child process?

In Unix/Linux terminology, do child processes of a process include grandchild processes of the process?
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how to determine how many times pid_max wrapped?

Is it even possible to know that? may be some kind of tests are required to be performed in order to find that information? My system, just after I login, seem to have already wrapped the max_pid, so ...
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LD_PRELOAD or similar to prevent network access

I'd like to start a program disconnected from the network (because immediately upon starting it tries to download huge amounts of data, which can be prevented by changing settings as soon as it ...
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Is it the process that cleans itself on termination or the kernel?

Recently I found this in a powerpoint presentation: When a program is compiled and linked, the linker inserts some extra code in the program. It is this code that calls the main function about the ...
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A way for saving running state of a program

I have a program that will perform a lengthy calculation which may take several days to be completed. Is there a way to save the program's running state; so I will be able to turn off the computer ...
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Is there a way to listen to process?

I want to know if there is a way to listen to a process in linux & unix - when it ends and what's the exit code of the process(script). I dont want to write a script that will run X seconds and ...
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Do sleeping processes get the same CPU time?

Some processes spend most of their "lives" in a sleep status. Daemons, servers and general listener come to mind. I was wondering if they get the same CPU time in that state? On something like my ...
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mmap() failed: Cannot allocate memory - how do I find out who's complaining?

mmap() failed is popping up in my .xsession-errors in bursts. But there's no indication about what application it is failing with. How do I look into this after it has happened? I usually discover the ...
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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 ...
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Will process ids be recycled? What if you reach the maximal id?

Process IDs are strictly increasing, but if your system runs long enough and there is a lot of processes terminating and starting, you could at some point reach the limit of the underlying integral ...
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What's the best way to determine the working directory for UNIX process using 'ps'?

I am running a Ruby command line script (rufus.sh)which ultimately calls Thread.new, which spawns a UNIX process as shown below. I run this script for more than 1 directory as the output of the ps ...
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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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How to kill a process started as daemon?

I start a process using foo &. It outputs something like: [1] 16915 This is the process id, I guess. How can I store this number into a variable named MY_PROCESS_ID (for example)? Then I ...
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Why pidof and pgrep are behaving differently?

I have a init script in /etc/init.d/myservice for initialize a service like this: ... start() { ... daemon /usr/sbin/myservice ... } stop() { ... pgrep myservice pidof myservice ps -ef ...
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Locate a directory from a relative path in ps output

When I executed the command to give the pid of my processes running, it gave me like this - user@machineA:/$ ps -eo pid,command | grep exhibitor | grep java | grep -v grep 1615 java -jar ...