子恢复时未发出SIGCHLD信号

Question

Here is my signal handler:

pid_t pid;
int status;
while (pid = waitpid(-1, &status, WNOHANG|WUNTRACED|WCONTINUED))
{
     printf("resume? %d\n", WIFCONTINUED(status));
}

It always prints out 0 even if I send a SIGCONT to a child process. If I send a SIGCONT to a group of processes using killpg , some processes are indicated to be resumed but some are not. Could somebody tell me why this happened?

Answer 1

SIGCHLD信号仅在子项已停止或终止时才显示，而在执行恢复时不显示。