在我 fork 一个 C++ 程序之后。运行 while 循环直到子进程终止的语法是什么。
int value = fork();
if( value = 0 ) {
//do something
} else {
while(childIsAlive) {
//do something
}
}
所做的事情是独立的。
最佳答案
int Stat;
if (waitpid(PidOfChild, &Stat, WNOHANG) == PidOfChild) {
if (WIFEXITED(Stat) || WIFSIGNALED(Stat)) {
childAlive = false;
}
}
waitpid 等待waitpid 中的状态更改。如果它返回 PidOfChild,则存在更改,并且 Stat 会更新。
如果子进程正常退出,WIFEXITED(Stat) 将为 true
如果子进程被信号终止,WIFSIGNALED(Stat) 将为 true。
编辑:示例代码。
#include <sys/types.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>
#include <errno.h>
#include <iostream>
#include <cstdlib>
using namespace std;
int main() {
srand(time(0));
pid_t pid = fork();
if (pid == 0) {
int Seconds = rand() % 3 + 1;
cout << "child: Sleeping " << Seconds << " seconds" << endl;
sleep(Seconds);
if (rand() % 2) {
cout << "child: Killing" << endl;
kill(getpid(), SIGTERM);
} else {
int ExitCode = rand() % 3;
cout << "child: Exiting with exit code " << ExitCode << endl;
exit(ExitCode);
}
} else if (pid > 0) {
for (;;) {
cout << "parent: spinning waiting for child to exit" << endl;
int Stat;
while (waitpid(pid, &Stat, WNOHANG) != pid);
if (WIFEXITED(Stat)) {
cout << "parent: Child exited with exit code " << WEXITSTATUS(Stat) << endl;
break;
} else if (WIFSIGNALED(Stat)) {
cout << "parent: Child killed with signal " << WTERMSIG(Stat) << endl;
break;
} else {
cout << "parent: Something else happened to child, e.g. STOPPED" << endl;
}
}
} else {
cout << "Error forking: " << strerror(errno) << endl;
}
}
关于C++在 child 还活着时循环,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/5057137/