Send signals to child process in Java

Question

I'm making a Java app which requires me to be able to pause (and resume) a child process ran with ProcessBuilder. I thought I could do it by sending the signals SIGSTOP and SIGCONT to the process, I googled it but I couldn't find anything regarding this.

How can I send a signal to a child process?

Yes, I can send data but how about sending signals? @HovercraftFullOfEels — Fr3ddyDev, Jul 18 '19 at 13:55
Define "signal"? How the process responds to the data is entirely dependent on that individual process — Hovercraft Full Of Eels, Jul 18 '19 at 13:56
Do you not know about [process signals](https://en.wikipedia.org/wiki/Signal_(IPC))? @HovercraftFullOfEels — Fr3ddyDev, Jul 18 '19 at 15:03

score 1 · Accepted Answer · answered Jul 18 '19 at 13:24

1

I don't know why you are opposed to kill, it is fairly straightforward.

int child_pid = 12345;
Runtime.getRuntime().exec("kill -SIGSTOP " + Integer.toString(child_pid));

answered Jul 18 '19 at 13:24

Zachary Oldham

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I think the OP wants to pause/resume the process, not kill it. – mwarren Jul 18 '19 at 13:32
@mwarren despite the name, kill doesn't actually kill a process. It sends signals that you specify - which could be sigkill if you want it to. – Zachary Oldham Jul 18 '19 at 13:35
How would I get the process PID from a `Process`? – Fr3ddyDev Jul 18 '19 at 13:54
@Fr3ddyDev `long pid = ProcessHandle.current().pid();` look at [this](https://stackoverflow.com/questions/35842/how-can-a-java-program-get-its-own-process-id) for more details – Zachary Oldham Jul 18 '19 at 14:04
@ZacharyOldham I think you meant `childProcess.pid()`. Killing the current (Java) process would not be a good idea. – VGR Jul 18 '19 at 14:31
`Cannot resolve method 'pid()'` @ZacharyOldham @VGR – Fr3ddyDev Jul 18 '19 at 16:10
@Fr3ddyDev Process ID methods were added as of Java 9. Is there a reason you’re using 8? – VGR Jul 18 '19 at 17:09

Send signals to child process in Java

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