在C++中安全地终止子进程可以使用以下方法：

使用waitpid()函数来等待子进程终止并收集其退出状态。可以在父进程中调用waitpid()函数来等待子进程的终止，确保子进程已经正常退出。这样可以避免僵尸进程的产生。

示例代码：

#include <iostream>#include <unistd.h>#include <sys/wait.h>int main() {pid_t pid = fork();if (pid == 0) {// 子进程逻辑std::cout << "Child process is running" << std::endl;// 子进程终止exit(0);} else if (pid > 0) {// 父进程逻辑std::cout << "Parent process is waiting for child process to terminate" << std::endl;int status;waitpid(pid, &status, 0);std::cout << "Child process has terminated with status: " << status << std::endl;} else {std::cerr << "Fork failed" << std::endl;}return 0;}

使用信号处理函数来捕获子进程的退出信号。可以在父进程中注册一个信号处理函数，捕获子进程的退出信号，然后在信号处理函数中处理子进程的终止状态。

示例代码：

#include <iostream>#include <unistd.h>#include <signal.h>void sigchld_handler(int signal) {int status;pid_t pid = waitpid(-1, &status, WNOHANG);std::cout << "Child process " << pid << " terminated with status: " << status << std::endl;}int main() {signal(SIGCHLD, sigchld_handler);pid_t pid = fork();if (pid == 0) {// 子进程逻辑std::cout << "Child process is running" << std::endl;// 子进程终止exit(0);} else if (pid > 0) {// 父进程逻辑std::cout << "Parent process is waiting for child process to terminate" << std::endl;while(1) {// 父进程持续运行}} else {std::cerr << "Fork failed" << std::endl;}return 0;}

这些方法可以确保在C++中安全地终止子进程，避免产生僵尸进程并正确处理子进程的退出状态。