where I can find some example of source code?

I am green hand for qnx.

#include <stdio.h>

int main(void)
{

printf("Hello world\n");

 return 0;

}

Maybe if you could explain what you want to do you we could be a little more precise. There is very little QNX specific code out there.

Thanks a lot!
How I receive SIGCHLD signal , then do something?

That’s a generic Unix programming question.

Check out Richard Stevens’ classic book: Advanced Programming in the UNIX(R) Environment