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

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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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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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2answers
137 views

My /var/log/ is mysteriously filling up GBs in minutes! Any cure before I re-install Debian 7?

Good morning, fellow *nix enthusiasts! I have been using Debian 7 for a while now and after a recent upgrade I noticed I constantly kept running out space on my root partition. I mean to the point ...
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1answer
684 views

Monitoring filesystem activity

Say, I have a program, and I want to monitor its filesystem activity (what files/directories are created/modified/deleted etc.) This program may be capable of spawning further processes, and thus, I ...
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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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587 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 ...
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797 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 ...
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66 views

How to kill a bunch of jobs based on ps output?

Here is output from ps: $ ps aux | grep blob ubuntu 4286 0.0 0.1 34748 9592 ? S Jan14 0:00 /usr/bin/python /usr/local/bin/pynt start_blob_reader ubuntu 4287 0.0 0.1 34748 ...
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125 views

How to not show the stdout output of a running process?

When a running process gives lots of stdout output throughout its lengthy running process, you don't want to kill it and rerun it. How can you not show the output? Thanks.
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How can process doing “vfork without exec” end up in a long uninterruptible sleep?

In this answer user suggests that Normally, Uninterruptible sleep should not last long, but as under windows, broken drivers or broken userpace programs (vfork without exec) can end up sleeping ...
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72 views

Preserve evidence of intrusion / deleted executable?

If you are faced with a non-root remote command execution vulnerability, and there is a foreign executable that's running on your Linux system from a user with only non-administrator privileges, ...
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I can't install new packages and can't update and upgrade

I'm trying to install some program on Ubuntu, but when I try it I got the following error.- E: Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable) E: Unable to lock ...
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3k views

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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1answer
267 views

Launch background processes in one group and later kill them all

The other day I tried writing a script that would kill a PID and all its children processes, but after spending some time on it, I decided it wasn't trustworthy, because sometimes some of the children ...
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2answers
949 views

Why is `sudo pkill -HUP -f “nginx: master process”` returning code 129 and no output

I'm trying to trigger a reload of the Nginx master process by using pkill and sudo. The server reloads fine, but I was just curious if anyone knows why the command sudo pkill -HUP -f "nginx: master ...
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Linux running slow with 0 swap left

Our Linux server is responding very slowly. top doesn't show any excessive CPU usage. I noticed that even though there's about 5GB of free memory, the system is using all of swap with no free swap ...
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Fork bomb on a Mac?

I just learned about a fork bomb, an interesting type of a denial of service attack. Wikipedia (and a few other places) suggest using :(){ :|:& };: on UNIX machines to fork the process an infine ...
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888 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 ...
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2k views

Disable random memory address generation in my programs

I'm reading "The art of exploitation" and would like to try some experiments, including reading from and writing to various memory address. I've created some simple programs and trying to overwrite ...
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576 views

retrieving names of all open pdf files (in evince or otherwise)

I constantly have many PDF files open. These are usually downloaded using chrome and immediately opened using evince. I sometimes want to persist the state of all my open PDF files, so I could ...
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1answer
59 views

CPU usage of file system operations not shown in top

I run the following command (which does ls for 10,000 times) in a Ubuntu Linux terminal and use the top command to monitor the CPU usage. While top shows the total CPU usage (line 2) is about 48% ...
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htop shows only the processes of the user that's running it?

On my old Debian Wheezy I see as a normal user without sudo all processes from all user in htop. On my new Debian Wheezy I only see my own processes. Old system kernel: 3.2.0-4 New system kernel: ...
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Determining maximum memory usage for an extremely short process

I have a program I am testing and I need to determine the maximum memory used by the process. I know that in general ps -aux can give me this information, but the process runs in under 1/10 seconds ...
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2k views

Maximum memory usable by a 32 bit RHEL 6 system

I have installed a 32 bit RHEL OS on a 64 bit system. From the wiki page of PAE: The Linux kernel includes full PAE mode support starting with version 2.3.23, with Linus Torvalds mentioning ...
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54 views

Suspend and edit previous single line commands

Say I want to modify the latter of some concatenated command line options, is it possible without killing the first command? Specifically I have compile and run scripts executed thusly: > compile ...
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439 views

How to know which commands are executed when I do something in GUI

This is for academic purpose. I want to know which commands are executed when we do something in GUI, for example creating a folder. I want to show that both the mkdir shell command and create folder ...
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137 views

Get process list with logical intersection of selectors?

The Linux ps command allows multiple selectors, such as user and command name, but always returns the logical OR of those selectors (more than I want). Does anyone know of a method or tool already ...
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How does forking affect a process's memory layout?

Please see the following figure showing the memory layout of a process: : When someone forks(), and a new task_struct is assigned, what happens to the addresses of the process? In more or less other ...
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795 views

controlling a process from a different session

So, I ssh into my remote computer and launch a process... time passes... my ssh session breaks. I log in again, and of course, I don't have access to the original process now. I can see it still if I ...
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start process so that it can't spawn new ones

Is it possible to start new process so that it couldn't spawn new ones (untrusted code)? Also how do I start a process so it couldn't make any input/output to files and in general any devices?
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828 views

Difference between process group and job?

What's the difference between a process group and a job? If I type pr * | lpr then is it both a process group as well a job? What exactly is the difference between a process group ID and a job ID? ...
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702 views

Alternative to iotop for non-root user without sudo privileges

I'm looking for an alternative to iotop. Here's my situation: I want to find out if a program is accessing the hard drive a lot while running. iotop requires root/sudo privileges. My account is on ...
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set packet rate limit via iptables

I have a packet rate limit (max. 10 per seconds) which is set by my internet provider. This is a problem if I want to use the AceStream player, because if I exceed the limit I get disconnected. How ...
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1answer
119 views

How to completely detach a process

I want to spawn a process and run it at the top level so that when the shell exits, the process keeps running. I had mistakenly thought that nohup would do this, but when I exit from the shell (the ...
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CPU percentage of a single process

How do I get the average CPU percentage (for every second) consumed by a single process since it starts until it ends (exists)? Could I make this with Top?
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What does it mean exactly when a processes “Time” has stopped in top?

I'll be looking into why we're getting critical swap alerts, and I'll find something like: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ SWAP COMMAND 14683 user1 30 10 16.0g 772m ...
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Get PID of the application running in the active terminal emulator

My end goal is to be able to open a new terminal window (urxvt) directly in the current working directory of the program running in the window currently active. I'm currently using the shell (Bash), ...
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Why “uninterruptible sleep” is not counted as “IDLE”?

When I run top -bi, where the parameter -i means "ignore idle processes", the resulted list(see below) of processes are either R or D, although there're S processes at that time. So, why ...
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ATOP shows red line vmcom and vmlim. What does it mean?

utility atop shows: ATOP - MyServer 2013/01/07 00:03:57 10 seconds elapsed PRC | sys 2.18s | user 8.33s | #proc 141 | #zombie 0 | #exit 0 | CPU | sys 21% | ...
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I don't want other users see my processes in ps aux. I have root. It's Debian. How to use grsec?

I installed 'linux-patch-grsecurity2' and it has some sort of interface. ~$ sudo gradm2 gradm 2.1.14 grsecurity administration program Usage: gradm [option] ... Examples: gradm -P ...
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587 views

Is it possible to send a keyboard event to a background script that's expecting user interaction? (Using 'read')

Ex: $read & [1] 15139 [1]+ Stopped $jobs -l [1]+ 15139 Stopped (tty input) read
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Raise Brightness When Maximizing Terminal

I'm looking to raise the brightness when I maximize or foreground the Terminal window which has Vim running. I would like to reset the brightness to normal when I minimize or background that process ...
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247 views

How to kill a process giving it a number of seconds before a doing the forced kill?

I do have the PID of the process to be killed but I do want to give it the chance to die peacefully, without doing a -9. Expected behaviour: check if PID is still running for up to ten seconds and do ...
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1answer
740 views

What process created this window with no PID associated? [duplicate]

Possible Duplicate: What process created this X11 window? I need to kill a process that spawned a window which seems to have no PID associated with it. At least that is what xdotool says: ...
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59 views

Is it possible to make an exec call that “returns”?

Is there a way to make the exec system call work like a function call that returns instead of totally replacing the current process image? My motivation is trying to integrate two shells with ...
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71 views

Disable networking only inside of a single terminal

I want to run a command in the terminal to disable networking, just in that terminal. How can that be accomplished? I'm running OSX. Note: I only want to disable the networking in that terminal. ...
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Strange cpu usage values reported by pidstat

I have a script that reports the cpu usage of a specific program reading values from pidstat. The script launches as: pidstat -C ^frontend$ -h -l -p ALL 1 1 The values reported this way sometimes ...
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How do I execute in background / return early?

For reference, I'm using phpseclib to control a remote SSH server using the 'root' account. I have to start/stop a java process which is ran in the background. Stopping works fine with killall java ...
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Getting pid of bash script from itself

I have a bash script with doing lot of things called script.sh: #!/bin/bash #It #Is #Doing #Things Is there a way that I be able to get the proccess of script and then kill it after 5 minutes? ...
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Graceful way to kill process

After my bash script is done with the selenium server, the script kills it like this: kill `ps -ef | grep selenium | awk '{ print $2 }'` While this works and it does kill the selenium script, it ...