how to check existence of a task by pid?

[Sebastien Lorquet]

Hi,

I have to check from a nuttx task that another task exists. I have the pid.

What is the best posix / nuttx way to "ping" a task ?

Something like

bool does_pid_exist(int pid);


Maybe kill with a specific signal that does nothing, but would fail if
the pid does not exist?

That would require me to implement this signal handler in all the tested
tasks (there would be several)

Thanks,

Sebastien

[Xiang Xiao]

kill(pid, 0);

please reference the code here:

https://github.com/apache/incubator-nuttx/blob/master/sched/signal/sig_dispatch.c#L309-L315

But you need to handle that task may exist after you get the answer.

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[Sebastien Lorquet]

Hello,

thanks, it also seems to work in nsh:

nsh> kill -0 6
nsh>
nsh> kill -0 10
nsh: kill: no such task: 10
nsh>

Sebastien

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