I start a background process from my shell script, and I would like to kill this process when my script finishes.

How to get the PID of this process from my shell script? As far as I can see variable ``$!`` contains the PID of the current script, not the background process.

How to get process ID of background process?

I am trying to use port 80 for my application server, but when I perform `netstat -aon` I get:

&gt; `TCP 0.0.0.0:80 0.0.0.0:0 LISTENING 4`

When I look up the process in task manager, it shows `PID 4` is `SYSTEM`, that&#39;s it. No extension... nothing. Just &quot;`SYSTEM`&quot;. What&#39;s going on here?

I&#39;m afraid to end this process, what do I do?


  [1]: https://stackoverflow.com/questions/108387/apache-and-iis-side-by-side-both-listening-to-port-80-on-windows2003

Port 80 is being used by SYSTEM (PID 4), what is that?

How do I get the id of my Java process? 

I know there are several platform-dependent hacks, but I would prefer a more generic solution.

How can a Java program get its own process ID?

I recently come across a file with the extension .pid and explored inside it but didn&#39;t find much. The documentation says:

&gt; A Pid-File is a file containing the process identification number (pid) that is stored in a well-defined location of the filesystem thus allowing other programs to find out the pid of a running script.

Can anyone shed more light on this, or guide me to details of what&#39;s contained in the pid file?

What is a .pid file and what does it contain?

In a bash script, I want to do the following (in pseudo-code):

    if [ a process exists with $PID ]; then
       
        kill $PID 
       
    fi

What&#39;s the appropriate expression for the conditional statement?

How to check if a process id (PID) exists

I have a script in Bash called `Script.sh`, and it needs to know its own PID (i.e. I need to get PID inside the Script.sh ) 

Any idea how to do this ?


How does a Linux/Unix Bash script know its own PID?

I have problem with Bash, and I don&#39;t know why.  
Under shell, I enter:

    echo $$    ## print 2433
    (echo $$)  ## also print 2433
    (./getpid) ## print 2602

Where `getpid` is a C program to get current _pid_, like:  

&gt;        int main() {
&gt;         printf(&quot;%d&quot;, (int)getpid());
&gt;         return 0;
&gt;        }

What confuses me is that:  

 1. I think &quot;(command)&quot; is a sub-process (am i right?), and i think its _pid_ should be different with its _parent pid_, but they are the same, why...  
 2. When I use my program to show _pid_ between parenthesis, the _pid_ it shows is different, is it right?  
 3. Is `$$` something like macro?

Can you help me?  

Why is $$ returning the same id as the parent process?

What is the simplest/best way to ensure only one instance of a given script is running - assuming it&#39;s Bash on Linux?

At the moment I&#39;m doing:

    ps -C script.name.sh &gt; /dev/null 2&gt;&amp;1 || ./script.name.sh

but it has several issues:

 1. it puts the check outside of script
 2. it doesn&#39;t let me run the same script from separate accounts - which I would like sometimes.
 3. `-C` checks only first 14 characters of process name

Of course, I can write my own pidfile handling, but I sense that there should be a simple way to do it.

What is the best way to ensure only one instance of a Bash script is running?

Is there a way to check to see if a pid corresponds to a valid process? I&#39;m getting a pid from a different source other than from `os.getpid()` and I need to check to see if a process with that pid doesn&#39;t exist on the machine. 

I need it to be available in Unix and Windows. I&#39;m also checking to see if the PID is NOT in use.

How to check if there exists a process with a given pid in Python?

I have a query related to the implementation of threads in Linux.

Linux does not have an explicit thread support. In userspace, we might use an thread library (like NPTL) for creating threads. Now if we use NPTL it supports 1:1 mapping.

The kernel will use the `clone()` function to implement threads.

Suppose I have created 4 threads. Then it would mean that:

- There will be 4 `task_struct`. 
- Inside the `task_struct`, there will be provision of sharing resources as per the arguments to clone `(CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND)`.

Now I have the following query:  

1. Will the 4 threads have the same PID? If someone can elaborate, how the PIDs are shared.  
2. How are the different threads identified; is there some TID (thread ID) concept?


If threads share the same PID, how can they be identified?

Anyone has experienced this problem?
Yesterday I still can run my app in simulator but now I cannot run my app since Xcode prints this error in console:

    error: failed to attach to process ID &lt;ID number&gt;

[![Screenshot for error][1]][1]

I have tried to reinstall, do this [post][2] and create new project but returns no luck.
Anyone can resolve this issue?

I use Xcode 4.5 Preview 2 and try to run iOS simulator 6


  [1]: http://i.stack.imgur.com/FzEfO.png
  [2]: https://stackoverflow.com/questions/10323481/thread-1-stopped-at-breakpoint-1/10323839#10323839

Failed to Attach to Process ID Xcode

As the title says, I&#39;m running multiple game servers, and every of them has the same `name` but different `PID` and the `port` number. I would like to match the `PID` of the server which is listening on certain port, and then I would like to kill this process. I need that in order to complete my bash script.

Is that even possible? Because it didn&#39;t find yet any solutions on the web.

Determine the process pid  listening on a certain port

I ve installed Postgresql and then ran a bunch of rails apps on my local Mac OSX Mountain Lion and created databases etc. Today after a while when I launched pgAdminIII and tried to launch a database server I got this error:

![enter image description here][1]


A quick google showed [this][2] post. More browsing pointed to the fact that there might be some sort of postmaster.pid file lying around that might be the root cause of this. If I delete that things would be fine.

However, before I go deleting stuff on my computer I wanted to make sure Im debugging this in a systematic way which would not result in more problems.

Somewhere I read that before deleting that file, I need to run this command:

      ps auxw | grep post

If I get no results then, its OK to delete the file. Else not. Well, I got this result of that command:

      AM               476   0.0  0.0  2423356    184 s000  R+    9:28pm   0:00.00 grep post



So now of course Im throughly confused. 

So what should I do?

Here is part of my postgres server error log:

     FATAL:  lock file &quot;postmaster.pid&quot; already exists
     HINT:  Is another postmaster (PID 171) running in data directory &quot;/usr/local/var/postgres&quot;?


Postgresql is still not running, still get the same error and nothing has changed. Im too chicken to delete things without checking on SO.

Could some of you experts please guide a noob.




Thanks


  [1]: http://i.stack.imgur.com/hOsJd.png
  [2]: https://stackoverflow.com/questions/8465508/can-not-connect-to-local-postgresql

Postgres DB not starting on Mac OSX: ERROR says: connections on Unix domain socket

I&#39;ve started a process with following code

     ProcessBuilder pb = new ProcessBuilder(&quot;cmd&quot;, &quot;/c&quot;, &quot;path&quot;);
     try {
         Process p = pb.start();       
     } 
     catch (IOException ex) {}


Now I need to know the process&#39;s pid that I&#39;ve just started.




How to get PID of process I&#39;ve just started within java program?

Is there any policy in Linux as to the recycling of used PIDs ? I mean, if a PId has been used, how much later will it be used again ?

Linux PID recycling

I&#39;m asking in both contexts: technically and stylistically.  

Can my application/daemon keep a pidfile in `/opt/my_app/run/`?

Is it very bad to do so?

My need is this: my daemon runs under a specific user, and the implementor must mkdir a new directory in `/var/run`, chown, and chgrp it to make my daemon run.  Seems easier to just keep the pidfile local (to the daemon).

Must my pidfile be located in /var/run?

I am porting an application from Tru64 to Linux and it uses PID_MAX defined in limits.h.
Linux doesn&#39;t have that define. 
How do I find PID_MAX in **c** without reading `/proc/sys/kernel/pid_max` by hand?
Is there a library?

Maximum PID in Linux

Can someone explain the structure of a Pid in Erlang?

Pids looks like this: `&lt;A.B.C&gt;`, e.g. `&lt;0.30.0&gt;` , but I would like to know what is the meaning of these three &quot;bits&quot;: `A`, `B` and `C`.

`A` seems to be always `0` on a local node, but this value changes when the Pid&#39;s owner is located on another node.

Is it possible to directly send a message on a remote node using only the Pid? Something like that: `&lt;4568.30.0&gt; ! Message`, without having to explicitly specify the name of the registered process and the node name (` {proc_name, Node} ! Message`)?


Can someone explain the structure of a Pid (Process Identifier) in Erlang?

What is the difference between PID and TID?

The standard answer would be that PID is for processes while TID is for threads. However, I have seen that some commands use them interchangeably. For example, `htop` has a column for PIDs, in which PIDs for threads of the same process are shown (with different values). So when does a PID represent a thread or a process?

Difference between PID and TID

I am trying to implement a simple log server in Bash. It should take a file as a parameter and serve it on a port with netcat.

    ( tail -f $1 &amp; ) | nc -l -p 9977

But the problem is that when the netcat terminates, tail is left behind running. (Clarification: If I don&#39;t fork the tail process it will continue to run forever even the netcat terminates.) 

If I somehow know the PID of the tail then I could kill it afterwards.  
Obviously, using $! will return the PID of netcat.

How can I get the PID of the tail process?

How to get the PID of a process that is piped to another process in Bash?

Hi I have searched various forums and here as well, I could find some answers for Linux and Mac but not able to find solution for Unix and specially Korn Shell.

How to get process name (command name) from process id (pid)

Below reference I found from SO 
[This one ][1]
[And this one also][2]

I tried below command

  [1]: https://stackoverflow.com/questions/4189717/get-process-name-by-pid
  [2]: https://stackoverflow.com/questions/15545341/process-name-from-its-pid-in-linux

    ps -eaf | awk &#39;{ print substr($0, index($0, $9)) }&#39;

Above command is failing at a point where TIME is given rather than Month and Date (because in this case there will be only 8 columns in string)

Any suggestion would help.

How to get pid given the process name

I am using the program synergy together with an ssh tunnel

It works, i just have to open an console an type these two commands:

    ssh -f -N -L localhost:12345:otherHost:12345 otherUser@OtherHost
    synergyc localhost

because im lazy i made an Bash-Script which is run with one mouseclick on an icon: 

    #!/bin/bash
    ssh -f -N -L localhost:12345:otherHost:12345 otherUser@OtherHost
    synergyc localhost

the Bash-Script above works as well, but now i also want to kill synergy and the ssh tunnel via one mouseclick, so i have to save the PIDs of synergy and ssh into file to kill them later:

    #!/bin/bash

    mkdir -p /tmp/synergyPIDs || exit 1
    rm -f /tmp/synergyPIDs/ssh || exit 1
    rm -f /tmp/synergyPIDs/synergy || exit 1
    
    [ ! -e /tmp/synergyPIDs/ssh ] || exit 1
    [ ! -e /tmp/synergyPIDs/synergy ] || exit 1

    ssh -f -N -L localhost:12345:otherHost:12345 otherUser@OtherHost
    echo $! &gt; /tmp/synergyPIDs/ssh
    synergyc localhost
    echo $! &gt; /tmp/synergyPIDs/synergy

But the files of this script are empty.

How do I get the PIDs of ssh and synergy?  
(I try to avoid `ps aux | grep ... | awk ... | sed ...` combinations, there has to be an easier way.)

How do I kill a backgrounded/detached ssh session?

  
By using &quot;ucbps&quot; command i am able to get all PIDs


 

     $ ucbps
      
       Userid     PID     CPU %  Mem %  FD Used   Server                  Port
       =========================================================================
          
       512        5783    2.50   16.30  350       managed1_adrrtwls02     61001
       512        8896    2.70   21.10  393       admin_adrrtwls02        61000
       512        9053    2.70   17.10  351       managed2_adrrtwls02     61002




I want to do it like this, but don&#39;t know how to do

1. variable=get pid of process by processname.
2. Then use this command kill -9 variable.


How to get PID of process by specifying process name and store it in a variable to use further?

I am writing a script to monitor the CPU and MEM of any given process. For that i need to send in the name of the process to be monitored as a commandline argument. For example. 

    ./monitorscript &lt;pname&gt;

I need to get the pid of the process in the script so that i can use a `ps -p &lt;pid&gt;` inside. 

How do i get the pid of a process given its process name? 

I understand that there might be multiple processes in the same name. I just want to get the first process out of that list. 



How to get the PID of a process by giving the process name in Mac OS X ?

I am having an issue where MySQL isn&#39;t starting on my QNAP NAS.

I found this first by not being able to log in through phpMyAdmin - was getting error: 

    #2002 Cannot log in to the MySQL server

I then went to attempt to start mysql, as I guess this is a common issue with this, but it just gave a generic error.

I went through troubleshooting the mysql.sock file and everything, changing its permissions, but nothing is working.

I have rebooted my NAS many times.

I eventually tried to restart mysql.  In doing so I get:

    ERROR! MySQL manager or server PID file could not be found!

I can&#39;t find anything specific to the QNAP or any general type troubleshooting for this.  Everything I find seems to be OSX related.

ERROR! MySQL manager or server PID file could not be found! QNAP

What&#39;s the logic behind calls like `getpid()` [returning a value of type][1] `pid_t` instead of an `unsigned int`? Or `int`? How does this help?

I&#39;m guessing this has to do with portability? Guaranteeing that `pid_t` is the same size across different platforms that may have different sizes of `int`s etc.?


  [1]: http://pubs.opengroup.org/onlinepubs/9699919799/functions/getpid.html

Why does getpid() return pid_t instead of int?

I&#39;m currently using a explicit cast to long and using `%ld` for printing `pid_t`, is there a specifier such as `%z` for `size_t` for `pid_t`?

If not what the best way of printing `pid_t`?


What is the correct printf specifier for printing pid_t

If there is more than one way, please list them.  I only know of one, but I&#39;m wondering if there is a cleaner, in-Ruby way.

How can I check from Ruby whether a process with a certain pid is running?

How can I get an android application pid without using adb shell? Is there any API to get pid.
any help will be appreciated

How to get pid of android application without using adb shell?

is anyone familiar with a way to get the Application pool that is associated with a process ID ?  I am using Win32_Process to query the W3WP services and return the PID now I am trying to get the app pool associated with it.


IIS Application pool PID

Given the pid of a Linux process, I want to check, from a C program, if the process is still running.

Check if process exists given its pid

Is there any way I can get the PID by process name in Python?

&lt;!-- language: lang-none --&gt;

      PID USER      PR  NI  VIRT  RES  SHR S  %CPU %MEM    TIME+  COMMAND                                                                                        
     3110 meysam    20   0  971m 286m  63m S  14.0  7.9  14:24.50 chrome 

For example I need to get `3110` by `chrome`. 


All Pid Solutions on Gang of Coders

Total of 32 Pid Solutions