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

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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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5answers
191 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 ...
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2answers
2k views

In bash script, how to capture stdout line by line

In a bash script, I would like to capture the standard output of a long command line by line, so that they can be analysed and reported while initial command is still running. This is the complicated ...
4
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2answers
740 views

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 ...
0
votes
1answer
74 views

Can a script be running even after it's been killed?

I know it sounds so stupid and I know it IS stupid but I ran a unix script to send me and my friend emails every few seconds to test mailx. Stupid thing is I used $ while true; do blah blah blah... ...
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0answers
20 views

What is the [rc0] kernel process?

I have several servers. A few of them are running ubuntu 12.04 LTS. I'm looking into an intermittent hanging issue, and noticed an [rc0] kernel process From ps -ef: ... root 1025 2 0 ...
12
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1answer
7k views

There are stopped jobs (on bash exit)

I get the message There are stopped jobs. when i try to exit a bash shell sometimes. Here is a reproducible scenario in python 2.x: ctrl+c is handled by the interpreter as an exception. ctrl+z ...
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1answer
80 views

Why my cpu spend so much time on system? [closed]

top - 08:58:42 up 20 days, 8:23, 1 user, load average: 67.17, 58.94, 62.75 Tasks: 630 total, 40 running, 524 sleeping, 0 stopped, 66 zombie Cpu(s): 57.3%us, 41.6%sy, 0.0%ni, 0.0%id, 0.0%wa, ...
0
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2answers
75 views

Why does kill not have a parameter for file and not for port number?

If I want to stop a program given its tcp port number or its file or named executable, can I run something like kill -tcpPortNumber $1 where the parameter $1 is a tcp port number or kill -filename $1 ...
2
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1answer
537 views

Find the PID's of all threads of a process without ps or pidof

So the system I'm working on (BusyBox) has a ps that takes no command line arguments and pidof returns nothing even though it exists within /sbin and points to killall5. Another issue I had is that ...
1
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1answer
46 views

Is there a way to check which process terminates first during reboot

Assuming I have 2 processes running. Is there any way for me to check which process terminates first during reboot/shutdown? From this link, it tells about appending boot to a file. Yet, I still don't ...
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1answer
203 views

Track down process that has notty

I have a Linux server (Red Hat 2.6 kernel) which had a spike in load due to an Rsync process which seems to have forked many times, but the process was run by rsyncuser@notty I didnt see any cron job ...
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2answers
619 views

How can a normal user trigger a root cron task to execute immediately, without delay?

I have a root cron task that runs every day. But I want to allow normal users to request that it run immediately, if they so wish. It is a harmless process and it can run as often as needed and these ...
1
vote
1answer
138 views

spawning multiple Background processes

I have a file which has 2,000,000 lines in it. I am running some commands for each line. I was trying to achieve some parallelism using GNU-parallel and swift as discussed here. However, I got an ...
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1answer
181 views

Gnu Parallel: more than one per CPU? [closed]

If I only have two cores, does parallel only run two processes at a time? I guess I'm still confused about processes, threads, and cores....
0
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1answer
85 views

How can I rejoin a process running

I am very new to using Linux. I have a 'machine' on Amazon and I was trying to learn how to use Python on this machine. I started running Python—had to step away for a few minutes and the connection ...
0
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1answer
135 views

Full path name of bash? and base process of Linux?

I am new to Linux and I recently had a test at school which had the following questions: What is the full path name of bash? What is the base process of Linux? I couldn't answer these. Does anyone ...
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3answers
1k views

A command which returns either a process ID, if running, or some other output if not?

I'm looking for a command that will give me the PID, and it's not running it should give me some output other than blank. In my program, sometimes the library I'm using gives blank output even if ...
2
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1answer
156 views

How to move process from one namespace to other?

This question is similar to my question about how to list namespaces. So in addtition, I'd like to know some information about moving processes from one namespace to other? E.g. I have processes of ...
1
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1answer
58 views

How do I identify the user that is attempting to create a file?

I have a PHP script that is attempting to create a file, but it can not because of permissions. I would like to identify which user the system sees as the one requesting to create the file. I would ...
8
votes
1answer
508 views

how to find out namespace of a particular process?

I already asked a question about how to list all namespaces in Linux, but there wasn't any correct and exact answers, so I want to find out a method which can help me to find out the namespace of PID ...
2
votes
1answer
121 views

How to renice a group of processes?

lb build can build live system image, and it invokes many processes while building the image. If I start it as below: # nice -n 19 ionice -n 7 -c 3 lb build all the children processes get the same ...
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1answer
65 views

tftpd runs as root, despite explicit option “--user tftp”

I start my tftp server with the option --user tftp so that it runs as user tftp instead of root. However, ps shows that the process still runs as root ps aux| grep tftp root 2542 0.0 0.0 ...
70
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2answers
6k 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 ...
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2answers
968 views

How do I run two ongoing processes at once in linux/bash?

I would like to know how I can run two ongoing processes at the same time in Linux/bash. basically, I have a Node web server, and a MJPG-Streamer server. I want to run both these processes at once, ...
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3answers
5k views

How to get the Job ID? [duplicate]

As we know, the shell enables the user to run background processes using & at the command line's end. Each background process is identified by a job ID and, of course, by it's PID. When I'm ...
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2answers
243 views

Why do forked processes sometimes appear with brackets [] around their name in ps? [duplicate]

On a Linux system a C process is started on boot, which creates a fork of itself. It is not a kernal process or something. In most cases a ps -ef show both processes as expecxted, but sometimes it ...
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2answers
66 views

Increase nice value for many processes

Say I have launched a couple of non-timecritical applications such as a text editor a web browser etc and one more time critical (audio)application. Is there a utility that simulates the opposite of ...
5
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2answers
412 views

Processes do not respond to my signals

I have a strange behavior on my system. When I invoke a command in the shell (bash version 4.2.45(1)-release), say top or cat, the running program (the process) does not respond to Ctrl+C. I even ...
9
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1answer
206 views

Why do I need dbus?

I recently removed dbus from my system (along with consolekit and polkit). I didn't notice any change (I was running it as system daemon and per-user from .xinitrc). However, many people claim that ...
8
votes
3answers
353 views

If you ^Z from a process, it gets “stopped”. How do you switch back in?

I accidentally "stopped" my telnet process. Now I can neither "switch back" into it, nor can I kill it (it won't respond to kill 92929, where 92929 is the processid.) So, my question is, if you have ...
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1answer
176 views

fg a bg process because you forgot to redirect output to /dev/null

I did Ctrl+Z bg with the intention of disowning next, but I forgot to redirect, now I cant get to my terminal because the scrolling of the output (tarballed a huge directory with verbose set). How do ...
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6answers
4k views

Does pressing ctrl-c several times make the running program close more quickly?

I often start to read a huge file and then want to quit after a while, but there is a lag from pressing Ctrl+C to the program stops. Is there a chance of shortening the lag by pressing the Ctrl+C key ...
0
votes
1answer
643 views

root permission denied on /proc/1/exe

I just performed a fresh ubuntu install and i am seeing the following in lsof: userA@az1:~$ lsof COMMAND PID TID USER FD TYPE DEVICE SIZE/OFF NODE NAME init 1 ...
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2answers
481 views

How to terminate a background process in Linux when the pid is unknown?

I have a job dispatcher bash shell script containing below codes: for (( i=0; i<$toBeDoneNum; i=i+1 )) do while true do processNum=`ps aux | grep Checking | wc -l` ...
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1answer
289 views

moving from user mode to kernel mode

I read the following: "All processes begin execution in user mode, and they switch to kernel mode only when obtaining a service provided by the kernel." When it says "obtaining a service ...
2
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1answer
1k views

How to check the status of bash shell script while executing from Python script?

I have a simple Python script which will execute a shell script using subprocess module in Python. Below is my Python shell script which is calling testing.sh shell script and it works fine. import ...
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3answers
264 views

Detect process if not found then run it

I am running several process at startup using "crontab -e" @reboot tranmission-daemon && python defualt.py && python MonitorService.py But for some reason, those service can ...
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2answers
4k views

Finding the PID of the process using a specific port?

I am installing hadoop on my Ubuntu system. When I start it, it reports that port 9000 is busy. I used netstat -nlp|grep 9000 to see if such a port exists and I got this: tcp 0 0 ...
3
votes
1answer
266 views

How does the piping in this command ultimately achieve to kill the process?

I have seen the following line in a bash script for killing a process(in this case started with the command loadgen): ps xww | grep -i "loadgen" | grep "PATTERNMATCH_FACT.xml" | cut -c1-5 | xargs -i ...
2
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2answers
50 views

Processes lose attachment to shell when started via bash -x

Normally, if I run emacs & and then close the shell, emacs will exit. However, if I run bash -x foo.foo (where foo.foo is a script that runs emacs &), then emacs will remain open even when I ...
0
votes
1answer
330 views

How to get pid of su --session-command file thats ran on there [closed]

This line ran in a script su --session-command="$javaCommandLine & >>$serviceLogFile 2>&1 & echo \$! >$pidFile" $serviceUser || return 1 pid="$(<$pidFile)" echo $pid The ...
6
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2answers
647 views

Why Process/program becomes zombie?

If script is running fine from command line then, why the same script becomes zombie state after running through cron and How you will troubleshoot the same ? Here following real example : [root@abc ...
4
votes
3answers
390 views

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 ...
5
votes
1answer
2k views

The meaning of output of pmap

I wrote main.c in Linux: int main() { while (1){} } When I compile and start it, I can pmap it: # pmap 28578 28578: ./a.out 0000000000400000 4K r-x-- /root/a.out 0000000000600000 4K ...
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2answers
313 views

How can I create a hard to kill process

I want to create a program that will be difficult to stop (even for the administrator) once it is started (with root privileges). Once started the process should continue to start itself at startup ...
2
votes
4answers
172 views

ssh ncat keeps ncat process running after disconnect; how do I prevent that?

If I run the command $ ssh othermachine ncat localhost 10000 that opens an ssh session to "othermachine" and pipes it into an ncat process. (There's something else listening on "othermachine" port ...
14
votes
4answers
22k views

How to stop a background process?

I have started a wget on remote machine in background using &. Suddenly it stops downloading. I want to stop its process, then start it again. How can I stop it? I haven't close its shell window. ...
9
votes
1answer
253 views

How can I track executables created by my user on Linux?

Using Linux, I would like to track the executables that are executed in my name, including the whole command line (in practice, every exec*() done as my own user). A program I do not control is ...
2
votes
2answers
162 views

Why do I see more processes in KVM than in OpenVZ?

I've got a 512mb Centos 6 VPS running on KVM. Now another VPS from a org. I manage is running on OVZ. When I type top on the KVM one, I get a whole list of all sort off processes. But when I do this ...