# How to know the childs PID of a given process? **URL:** \ **Category:** Ruby\ **Created:** [January 4, 2010, 12:32pm UTC](https://www.ruby-forum.com/t/how-to-know-the-childs-pid-of-a-given-process/181045 "2010-01-04T12:32:52Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![ISSSSaki\_Baz\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/51bf81/32.png) [@ISSSSaki\_Baz\_C](https://www.ruby-forum.com/u/ISSSSaki_Baz_C)\ **Post date:** [January 4, 2010, 12:32pm UTC](https://www.ruby-forum.com/t/how-to-know-the-childs-pid-of-a-given-process/181045/1 "2010-01-04T12:32:52Z")
Hi, I know that a Ruby process with PID 1000 (under Linux) has forked 4 times. How could I know the PID of those childs from any other ruby interpreter? This is, I just know the PID of the parent (1000). Of course I could do some hack as inspecting the output of “ps” and inspecting the pid/ppid, but I’d prfer a ppure Ruby method for this. Thanks for any suggestion. ---
**Author:** ![ISSSSaki\_Baz\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/51bf81/32.png) [@ISSSSaki\_Baz\_C](https://www.ruby-forum.com/u/ISSSSaki_Baz_C)\ **Post date:** [January 4, 2010, 2:21pm UTC](https://www.ruby-forum.com/t/how-to-know-the-childs-pid-of-a-given-process/181045/2 "2010-01-04T14:21:10Z")
On 01/04/2010 11:52 AM, Iñaki Baz C. wrote: > Hi, I know that a Ruby process with PID 1000 (under Linux) has forked 4 times. > How could I know the PID of those childs from any other ruby interpreter? > This is, I just know the PID of the parent (1000). > > Of course I could do some hack as inspecting the output of “ps” and inspecting > the pid/ppid, but I’d prfer a ppure Ruby method for this. > > Thanks for any suggestion. The typical approach is that the forking parent records PIDs of its children. If that information needs to be propagated you can either write it to a file or make it available via DRb. If you need multiple Ruby processes to collaborate I would probably turn to DRb anyway. In that case you might not even need to record PIDs but you could have a coordinator where processes register and unregister or which starts processes itself. It depends on your use case. Kind regards robert ---
**Author:** ![ISSSSaki\_Baz\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/51bf81/32.png) [@ISSSSaki\_Baz\_C](https://www.ruby-forum.com/u/ISSSSaki_Baz_C)\ **Post date:** [January 4, 2010, 3:22pm UTC](https://www.ruby-forum.com/t/how-to-know-the-childs-pid-of-a-given-process/181045/3 "2010-01-04T15:22:02Z")
El Lunes, 4 de Enero de 2010, Robert K. escribió:\> The typical approach is that the forking parent records PIDs of its > children. If that information needs to be propagated you can either > write it to a file or make it available via DRb. > > If you need multiple Ruby processes to collaborate I would probably turn > to DRb anyway. In that case you might not even need to record PIDs but > you could have a coordinator where processes register and unregister or > which starts processes itself. It depends on your use case. Thanks a lot. The fact is that I’d like not to modify the program whose processes I want to monitor, so I was looking for something as “ps”. Thanks a lot. ---
**Author:** ![ISSSSaki\_Baz\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/51bf81/32.png) [@ISSSSaki\_Baz\_C](https://www.ruby-forum.com/u/ISSSSaki_Baz_C)\ **Post date:** [January 4, 2010, 4:34pm UTC](https://www.ruby-forum.com/t/how-to-know-the-childs-pid-of-a-given-process/181045/4 "2010-01-04T16:34:01Z")
On Jan 4, 7:21 am, Iñaki Baz C. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Thanks a lot. The fact is that I’d like not to modify the program whose > processes I want to monitor, so I was looking for something as “ps”. > **[GitHub - djberg96/sys-proctable: A cross-platform Ruby interface for...](https://github.com/djberg96/sys-proctable)** > > A cross-platform Ruby interface for gathering process information on your operating system - GitHub - djberg96/sys-proctable: A cross-platform Ruby interface for gathering process information on yo... Regards, Dan ---
**Author:** ![ISSSSaki\_Baz\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/51bf81/32.png) [@ISSSSaki\_Baz\_C](https://www.ruby-forum.com/u/ISSSSaki_Baz_C)\ **Post date:** [January 4, 2010, 4:51pm UTC](https://www.ruby-forum.com/t/how-to-know-the-childs-pid-of-a-given-process/181045/5 "2010-01-04T16:51:35Z")
El Lunes, 4 de Enero de 2010, Daniel B. escribió: > [GitHub - djberg96/sys-proctable: A cross-platform Ruby interface for gathering process information on your operating system](http://github.com/djberg96/sys-proctable) There is a typo in the README: gem install sys-proctalbe --platform linux # Linux (note “proctalbe”) 😉 ---
**Author:** ![ISSSSaki\_Baz\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/51bf81/32.png) [@ISSSSaki\_Baz\_C](https://www.ruby-forum.com/u/ISSSSaki_Baz_C)\ **Post date:** [January 4, 2010, 4:49pm UTC](https://www.ruby-forum.com/t/how-to-know-the-childs-pid-of-a-given-process/181045/6 "2010-01-04T16:49:50Z")
El Lunes, 4 de Enero de 2010, Daniel B. escribió:\> \> \> > > Thanks a lot. The fact is that I’d like not to modify the program whose > > processes I want to monitor, so I was looking for something as “ps”. > > [GitHub - djberg96/sys-proctable: A cross-platform Ruby interface for gathering process information on your operating system](http://github.com/djberg96/sys-proctable) Really interesting, thanks a lot!