Questions tagged [process-management]

Use this tag when the topic is about system process management. Commands used for this are like ps and kill -9 xxxx and service xyz start|stop|restart and htop, for example. Often used in conjunction with memory management.

Filter by
Sorted by
Tagged with
400
votes
9answers
161k views

When should I not kill -9 a process?

I am always very hesitant to run kill -9, but I see other admins do it almost routinely. I figure there is probably a sensible middle ground, so: When and why should kill -9 be used? When and why ...
22
votes
9answers
42k views

Ensure a process is always running

I started hosting sites a while back using Cherokee. For external sources (FastCGI, etc) it has an option to launch the process if it can't find one running on the designated socket or port. This is ...
27
votes
2answers
57k views

How can I kill a <defunct> process whose parent is init?

Transmission is intermittently hanging on my NAS. If I send SIGTERM, it doesn't disappear from the process list and a <defunct> label appears next to it. If I send a SIGKILL, it still doesn't ...
19
votes
6answers
20k views

How to make a process invisible to other users?

How could you launch a process and make it invisible to the top command? The process is started by a normal user (not root), and should not be visible to other normal users.
23
votes
1answer
8k views

How to ensure exclusive CPU availability for a running process?

At first, the question seems to be a little bit silly/confusing as the OS does the job of managing process execution. However, I want to measure how much some processes are CPU/IO-bound and I feel ...
18
votes
2answers
10k views

Per process firewall?

I've been reading around but can't seem to find a way to create per-process firewall rules. I know about iptables --uid-owner but that only works for outgoing traffic. I've considered scripting ...
44
votes
2answers
5k views

Why is the default process creation mechanism fork?

The UNIX system call for process creation, fork(), creates a child process by copying the parent process. My understanding is that this is almost always followed by a call to exec() to replace the ...
30
votes
4answers
15k views

What happens if you edit a script during execution?

I have a general question, which might be a result of misunderstanding of how processes are handled in Linux. For my purposes I am going to define a 'script' as a snippet of bash code saved to a text ...
4
votes
1answer
4k views

Orphan process's parent id is not 1 when parent process executed from GNOME Terminal

I start a new process from GNOME Terminal and then this process fork a child. But when I killed the parent process the orphaned process's parent id became something other than 1 which represent init -...
2
votes
2answers
753 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 ...
30
votes
4answers
36k views

How to Throttle per process I/O to a max limit?

I'm looking for a way to limit a processes disk io to a set speed limit. Ideally the program would work similar to this: $ limitio --pid 32423 --write-limit 1M Limiting process 32423 to 1 megabyte ...
41
votes
1answer
70k views

What does this process STAT indicates?

If you check the STAT column in above image you will see Ss S S< SN and R+ What does this indicates ? Process states. If yes,Then what is the significance of 'Ss S< SN and R+'?
46
votes
4answers
22k views

What's the difference between pkill and killall?

I know that pkill has more filtering rules than killall. My question is, what is the difference between: pkill [signal] name and killall [signal] name I've read that killall is more effective and ...
35
votes
1answer
5k 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?
20
votes
3answers
201k views

How can I see what processes are running?

I use Ubuntu Server 10.10 and I would like to see what processes are running. I know that PostgreSQL is running on my machine but I can not see it with the top or ps commands, so I assume that they ...
11
votes
2answers
12k views

How to check, which limit was exceeded? (Process terminated because of ulimit. )

Let's assume process runs in ulimited environment : ( ulimit ... -v ... -t ... -x 0 ... ./program ) Program is terminated. There might be many reasons : memory/time/file limit exceeded ; just ...
0
votes
2answers
229 views

Is there the possibility to set a parent process when creating a new process?

I'd like to set the parent of a newly started process, is that possible? Example, let us assume that we start a new desktop environment session via a login manager, so our process tree would look ...
6
votes
2answers
2k views

Removing zombie process from the process table

Can somebody please explain when parent process receives the exit status of a dead child process via wait, who actually reallocates the memory of the child process and removes it from the process ...
1
vote
1answer
6k views

kill processes in one line with kill, awk, ps, and grep

I have a few processes that spring up and I am able to print a line of the pgid's that I would like to enter into a kill command. here is what I have: sudo ps o pgid,args | grep mininet: | sudo awk '{...
51
votes
3answers
16k views

Getting a window's PID by clicking on it

Is there any package which shows PID of a window by clicking on it?
16
votes
5answers
44k views

What is the difference between ps and top command?

What is the difference between ps and top command ? I see that both can display information about running processes . Which one should be used when ?
30
votes
4answers
20k views

Is there a top-like command that shows the network bandwidths and file accesses of running processes

For example, we'd like to see: PROCESS IF TX RX FILE(regular) R/W prog1 eth0 200kB/s 12kB/s -- -- wlan0 12kB/s 100kB/s -- ...
8
votes
2answers
25k views

Run commands in parallel and wait for one group of commands to finish before starting the next

I have script including multiple commands. How can I group commands to run together ( I want to make several groups of commands. Within each group, the commands should run in parallel (at the same ...
18
votes
2answers
4k views

What does a niceness value of (-) mean?

According to the man page, and wikipedia; nice ranges from -20 to 20. Yet when I run the following command, I find some processes have a non numerical value such as (-). See the sixth column from ...
29
votes
4answers
3k views

python vs bc in evaluating 6^6^6

I am evaluating the expression 6^6^6 using python and bc separately. The content of the python file is print 6**6**6. When I execute time python test.py, I get the output as real 0m0.067s ...
17
votes
2answers
960 views

How are the processes in UNIX numbered?

I can't find any pattern when I look at the numbering of PIDs in process table (ps -a), as the PIDs are not subsequent numbers and sometimes there are large "gaps" between those numbers. Is it ...
13
votes
3answers
7k views

Simulate an unkillable process in D state

For catastrophe testing scenarios on out server environment we're looking for an easy way to make a process stuck in D (uninterruptible sleep) state. Any easy ways? An example C sample code would be ...
4
votes
2answers
2k views

How to run groups of commands in parallel?

I am trying to run groups of commands in parallel. There are 10 groups and each group has 3 commands. I want sequential execution within each group and parallel execution of the 10 groups. I am trying ...
4
votes
2answers
10k views

Mysterious bash instances using a lot of CPU, how can I debug?

I seem to have multiple bash processes running that are taking up most of my CPU. This is the output of top -c: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 20116 ...
8
votes
5answers
13k views

'kill java' doesn't kill java

I am running debian right now and sometimes I need to kill java manually from the terminal, but when I try kill #pid# or pkill java nothing happens. No console output (ok, that's normal) and java is ...
5
votes
1answer
4k views

What is the difference between exiting a process via Ctrl+C vs issuing a kill -9 command?

I know I can kill any process with kill -9 command . But sometimes i see that even if I have terminated a program with CTRL+C , the process doesn't get killed . So I want to know the difference ...
27
votes
2answers
1k views

Can a zombie have orphans? Will the orphan children be disturbed by reaping the zombie?

As I understand it, a zombie process has died but still exists as a placeholder in the process table until its parent (or init if the zombie is itself an orphan) checks its exit status. And my ...
16
votes
2answers
5k views

How should I check whether a given PID is running?

I'm writing a Perl script that parses logfiles to collect PIDs and then checks whether that PID is running. I am trying to think of the best way to make that check. Obviously, I could do something ...
8
votes
1answer
2k views

Difference between closing the terminal using the closing button, and Ctrl-D

When I'm launching a background process and then closes the terminal using the window's closing button, the background process gets killed. However if I close the terminal using Ctrl+D, the background ...
6
votes
2answers
5k views

How does systemd handle the death of a child of a managed process?

How does systemd handle the death of the children of managed processes? Suppose that systemd launches the daemon foo, which then launches three other daemons: bar1, bar2, and bar3. Will systemd do ...
1
vote
1answer
408 views

What happens to a unix session when the session leader exits?

I'm trying to properly emulate POSIX signals handling and job control for my pet operating system, but it's not clear to me what should happen to a session after the session leader exits. I cannot ...
1
vote
1answer
166 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 ...
3
votes
2answers
1k views

Running a daemon as a non-privileged user

I am trying to set up a Thin Ruby application server on my Ubuntu VPS. I have created a specific account, installed rbenv under it along with all gems. I am looking for a convenient way to obtain the ...
3
votes
2answers
169 views

What information about a process is retrievable after it is terminated?

After a process has been terminated, is it possible to retrieve any information about it, such as when it started and finished, &c. Is it possible to enable logging of this information?
3
votes
1answer
267 views

Can a Linux-process intercept signals sent to its child?

I have a shell-wrapper around a large executable. It does something like this: run/the/real/executable "$@" & PID=$! # perform # a few # minor things wait $PID # perform some # post-processing ...
3
votes
1answer
842 views

Prevent gnome-pty-helper from running again

I terminated the gnome-pty-helper process with $ kill -9 9753 After a while it was running again with another process number. There wasn't a restart of a system. Why is it located under ~/.config/...
2
votes
3answers
2k views

How do I start a server via ssh and have it run after I log out?

I ssh into a virtual server and start up a web server. Everything runs as expected. But when I close my terminal on my laptop, the process dies on the virtual server. How do I fix this?
2
votes
5answers
2k views

Replace instance of process in place?

I suspect this is not doable just because of the security implications, but here's what I'd like to do. Basically we run a bash shell-script on our CentOS server that calls Program-A (in our case ...
1
vote
2answers
143 views

Terminal command (called not from SU) that would restrict process from writing to all directories but one?

We have an app testApp. We have a folder called notRestricted in the directory where we run app from. We want to limit access of the app to file system so that app could write only to that folder (we ...
0
votes
3answers
2k views

How to allocate a process specific amount of CPU power? [duplicate]

I would like to allocate certain number of CPU cores to a specific process for performance improvement. How can I do this?
0
votes
1answer
376 views

Custom “garbage collector” to manually close a program

I'm running Ubuntu 16.04 I have this process X running from multiple tty. I run it from other pseudo terminals using the screen command and it also runs from crontab. This program is launched from a ...