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

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How does the Linux scheduler determine if a process is I/O bound or CPU bound

Adding to this question, how does the scheduler determine if a process is I/O bound or CPU bound? Mr. Love in this article, says "schedulers often employ complex algorithms to determine the most ...
1
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0answers
22 views

Background processes in ksh script are disappearing after they are kicked off

I'm having an issue with a KSH script that is supposed to kick off four processes in parallel in the background and then poll their status. Put simply, running the four processes sequentially would ...
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1answer
1k 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 ...
9
votes
1answer
12k views

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 ...
0
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1answer
50 views

Process tree using fork() [closed]

I am given the task of creating this process tree in C using fork, if and else: |_____1___ |___2__ | |_4_ | |_3_ | | | | | Or as a pstree like drawing: p(0)─┬─p(1)───p(3) ├─p(2) ...
91
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5answers
106k views

How to check how long a process has been running?

I would like to avoid doing this by launching the process from a monitoring app.
0
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1answer
1k 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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4answers
592 views

list graphical processes from terminal

Do no confuse the question here with how to list processes graphically, that is not what I am asking. In the Terminal, how can i see which processes have a GUI? as in things like firefox, vlc, ...
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2answers
43 views

How can I kill my backticked yes process?

I was playing around in my terminal, which runs zsh. I typed the following: $ ` bquote> yes bquote> ` And then, yes started to run in the background, I think. Neither Ctrl + C nor Ctrl + \ ...
2
votes
2answers
111 views

How to set an indentifier for multiple background processes?

I'm creating a custom game server and I have a .jar file to run it. I need to launch multiple game servers on a single virtual machine(like 15). I found, that I could just run them like this: java ...
5
votes
3answers
32k views

Fix “firefox is already running” issue in Linux

I am trying to open Firefox in CentOS, but I'm getting the following message: Firefox is already running but is not responding and Firefox doesn't open. I tried this in command line: kill ...
3
votes
2answers
40 views

How to find what processes run by the user right now?

Once again, I'm a beginner and I can't find the right command. I want to view the processes that I'm currently running.
3
votes
1answer
39 views

`EINTR`: is there a rationale behind it?

Small talk as background EINTR is the error which so-called interruptible system calls may return. If a signal occurs while a system call is running, that signal is not ignored and a signal handler ...
1
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1answer
30 views

Retrieve data from mem cache

Newbie to Linux. My application writes to a log file and for some reason it stopped writing to that file suddenly. We have restarted the application to fix this glitch. Is it possible to retrieve the ...
7
votes
10answers
25k views

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 ...
2
votes
3answers
108 views

lsof -p PID vs lsof | grep PID

I do not understand the ouput of the lsof command. When i write lsof -p PID I get 4 lines and when I write lsof | grep PID I get hundreds of lines. Shouldn't it return the same result? ...
91
votes
4answers
57k views

How do I read from /proc/$pid/mem under Linux?

The Linux proc(5) man page tells me that /proc/$pid/mem “can be used to access the pages of a process's memory”. But a straightforward attempt to use it only gives me $ cat /proc/$$/mem ...
2
votes
4answers
16k views

process id and killing process - ps commmand

Please see the output of below ps command: abc@smaug:~/Desktop$ ps ax | grep firefox 2213 ? Sl 2:01 /usr/lib/firefox/firefox 2644 pts/0 S+ 0:00 grep --color=auto firefox Please ...
2
votes
1answer
37 views

How is sudo interrupted in xterm on Ctrl-C? [duplicate]

Please explain in detail (including tty related stuff) how is a sudo foreground process on a X terminal emulator actually killed on the Ctrl-C. See the following example please: $ sudo -u test_no_pw ...
11
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5answers
10k views

How to send keystrokes (F5) from terminal to a process?

I'm using an Raspberry Pi in combination with Chromium (kiosk mode) to show up some stats. The Pi doesn't have an connected keyboard so I searched for a solution to send keystrokes from the terminal ...
1
vote
1answer
32 views

Security - Runing Daemon, program as root or user vs sudo su

I have some questions about Linux security: Running a process as root is a big mistake (root has too much power + a program get too much permissions in the system). I always ran processes as a user ...
2
votes
1answer
104 views

Why do I have 9 bash processes, why does one of them take up so much CPU and how do I stop them?

I have 9 different bash processes running at all times (I sometimes get more, for example, I have 37 bash processes now.). I found this question, where OP had a similar issue. But I don't see this as ...
4
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2answers
52 views

How do I find the PID of a particular program?

I would like to write a Bash script that searches for PIDs matching a program's name (perhaps using ps ax | grep <PROGRAM> or something similar) and feeds them to pixelb's ps_mem script. ps_mem ...
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0answers
5 views

How to see the variables current value of a running matlab process on tmux?

I have a matlab process in tmux which is running for days. Actually I need to see the values of calculated variables till now. I thought that, it is good(if possible) to duplicate the process and then ...
0
votes
1answer
32 views

How to extract all links from a given url in a decent time

I'm trying to extract the links from a specified url and redirect them to a file. At first I tried using --spider , this is my code: wget --spider --force-html -m http://file/path 2>&1 | grep ...
29
votes
6answers
8k views

Who's got the other end of this unix socketpair?

I want to determine which process has the other end of a UNIX socket. Specifically, I'm asking about one that was created with socketpair(), though the problem is the same for any UNIX socket. I ...
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2answers
23 views

View current user process ancestors and formating the output

I'm using ps -eo ppid,pid,cmd to view all process, and how can I format the output to view like below? Only given PID and its ancestor will print (until init). 23464 current | 23211 bash | ...
47
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5answers
6k views

How can I check what signals a process is listening to?

How can I verify whether a running process will catch a signal, or ignore it, or block it? Ideally I'd like to see a list of signals, or at least not have to actually send the signal to check.
30
votes
1answer
1k views

What is a “subreaper” process?

The word "subreaper" is used in some answers. Searching Google also turn up entries where the word is "just used". How can I understand what a "subreaper" is?
1
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1answer
25 views

Find the command the application has spawned

Is there a way to find the command by which an application has launched an external process? Motivation: I'm using an IDE Qt Creators which at some point calls a SFTP to transfer a file to a remote ...
2
votes
1answer
27 views

Find process that stalls apache

I'm programming a PHP web page and I started seeing some strange behavior on my computer, at some point apache / php takes to long to show the webpage on the browser (8 secs), first i thought it was ...
0
votes
0answers
12 views

Memory sections for Process and Thread

We know very well that Stack,Heap,Data and Code sections are created when we load any program into main memory.I want to know that what are memory sections created for Thread if I create for same ...
0
votes
1answer
27 views

strace vs web browser

I was trying to strace an iceweasel like this: strace -e trace=connect iceweasel And I was expecting to see calls to connect when I load new pages. Surprisingly, there weren't any. Why so? Am I ...
0
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1answer
33 views

which process was running on a particular time in linux [duplicate]

Is there any way to find which process was running on a particular time in linux? I found the disk utilization was 99% and CPU utilization was 100% on two different times yesterday. The issue was ...
0
votes
1answer
16 views

Help with the PS and TTY?

I have this question for you guys: I execute on a different shell 'sleep 600'. I open a different terminal and I executed 'ps' to see my current process , however , I dint see any sleep process. I ...
0
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0answers
12 views

Supervisord fails to run a program

I've a program that I try to run with supervisord but keep failing. The following is supervisord configuration: $ cat /etc/supervisor/conf.d/application.conf [program:application-web-1] command=env ...
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3answers
22 views

Output of processes and specific users with adding some text

I have tried to output processes for specific user but with adding some text. I can do like it is described in this answer How to see process created by specific user in Unix/linux but I don't know ...
0
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0answers
16 views

High CPU usage after Version Upgrade

Not sure if is related to the version upgrade but since I have updated my Raspberry to Linux version 4.1.13+ (dc4@dc4-XPS13-9333) (gcc version 4.8.3 20140303 (prerelease) (crosstool-NG ...
57
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4answers
12k views

Why do we need to fork to create new processes?

In Unix whenever we want to create a new process, we fork the current process, creating a new child process which is exactly the same as the parent process; then we do an exec system call to replace ...
3
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2answers
66 views

Content of /proc/<PID>/cmdline file depends on script shebang?

I have a bash script named test.sh which I start with startproc. In case I use #!/usr/bin/env bash shebang in test.sh, the /proc/<PID>/cmdline file looks following: SERVER:~ # cat ...
2
votes
1answer
72 views

iotop showing 1.5 MB/s of disk write, but all programs have 0.00 B/s

I don't understand iotop output: it shows ~1.5 MB/s of disk write (top right), but all programs have 0.00 B/s. Why? The video was taken as I was deleting the content of a folder with a few millions ...
18
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6answers
7k views

Can ps display only non kernel processes on Linux?

How can I ask ps to display only user processes and not kernel threads? See this question to see what I mean...
16
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2answers
3k 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 ...
6
votes
2answers
8k views

Is it possible to get process group ID from /proc?

In "http://stackoverflow.com/questions/13038143/how-to-get-pids-in-one-process-group-in-linux-os" I see all answers mentioning ps and none mentioning /proc. "ps" seems to be not very portable ...
1
vote
2answers
71 views

Shell script to kill processes except those owned by user

I am Looking for some help in creating a script to kill processes, but return an error message if they are owned by root. Firstly I would like to say that I am a total beginner at this. At the moment ...
9
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1answer
5k 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 ...
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3answers
127 views

How to kill a command executed from a script?

I would like to start a tcpdump in my own script an after some time I would like to kill it again. How can I access the PID from the tcpdump. I tried it with $$ , but this only kills the script. if ...
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1answer
42 views

Kill process on specific port

It has been asked before but how to do it with OpenBSD? I tried some different method but none worked. $ sudo fuser -k 80/tcp fuser: 80/tcp: No such file or directory $ kill $(sudo lsof -t -i:80) ...
234
votes
12answers
207k views

What if 'kill -9' does not work?

I have a process I can't kill with kill -9 <pid>. What's the problem in such a case, especially since I am the owner of that process. I thought nothing could evade that kill option.
26
votes
4answers
38k views

How to view the output of a running process in another bash session?

I have left a script running on a remote machine from when I was locally working at it. I can connect over SSH to the machine as the same user and see the script running in ps. $ ps aux | grep ...