是否可以恢复被杀死的子进程？

Question

我想写一个基本的过程控制块的程序，下面的代码显示了我在测试阶段做了什么，我想知道如果是的话，我们是否可以恢复一次孩子而不是再次分岔一个新孩子我们如何做到这一点。 在此先感谢！
代码：
`

#include<sys/types.h> 
    #include<sys/wait.h> 
    #include<unistd.h> 
    #include<time.h> 
    #include<stdio.h> 
    #include<unistd.h> 
    #include<time.h> 
    #include<stdio.h> 
    #include<stdlib.h> 
int hell() 
    { 
    int j; 
    for(j=1;j<6;j++) 
    printf("%d hello\n",j);` 
    } 
int hello(k) 
    {  
int i 
for(i=1;i<15;i++ 
printf("%5d hello \n", i); 

    } 
void sigint() 
    { 
    signal(SIGCONT,sigint); /* reset signal */ 
    printf("CHILD: I have received a SIGINT\n"); 
    } 
int main() 
    { 
int i, status; 
pid_t childID, endID,end1id,parentid; 
time_t when; 

label: if ((childID = fork()) == -1) { 
    perror("fork error"); 
    exit(EXIT_FAILURE); 
} 
else if (childID == 0) { 
    time(&when);hell(); 
    printf("k value %d\n",hello(5)); 
    printf("Child process started at %s\n", ctime(&when)); 
    printf("child PID : %d \n",getpid()); 

    hello(); 
    sleep(10); 
    //kill(childID, SIGKILL);     

    exit(EXIT_SUCCESS); 
} 
} 
else { 
    time(&when); 
    printf("Parent process started at %s", ctime(&when)); 
    printf("parent PID : %d\n",getpid()); 
      hell(); 
     parentid = getpid(); 
for(i = 0; i < 15; i++) { 
     endID =waitpid(childID,&status,WNOHANG|WUNTRACED);  
    printf("endid: %d\n",endID); 
     end1id = waitpid(parentid, &status, WNOHANG|WUNTRACED);  
     if (endID == -1) { 
      perror("waitpid error"); 
      exit(EXIT_FAILURE); 
     } 
     else if (endID == 0) { 
      time(&when); 
      printf("Parent waiting for child at %s", ctime(&when)); 
      sleep(1); 
     } 
     else if (endID == childID) { 

      if (WIFEXITED(status)) 
      printf("Child ended normally\n\n"); 
      else if (WIFSIGNALED(status)){ 
     printf("Child ended because of an uncaught signal\n");goto label;} 
      else if (WIFSTOPPED(status)){ 
      printf("Child process has stopped\n");goto label;} 
      exit(EXIT_SUCCESS); 
     } 
} 
} 

Answer 1

当您发出kill命令，你可以使用SIGSTOP没有使它模具然后恢复它离开的地方使用SIGCONT暂停它的孩子。

#include <stdio.h> 
#include <unistd.h> 
#include <signal.h> 

int main() { 
    pid_t childId; 

    if ((childId = fork()) == -1) { 
     printf("child fork failed\n"); 

    } else if (childId == 0) { 
     int i = 0; 
     while (1) { 
     printf("infinite child loop ==> %d\n", ++i); 
     sleep(1); 
     } 

    } else { 
     printf("parent: child started OK\n"); 
     sleep(5); 
     printf("parent: stopping child - but letting it live\n"); 
     kill(childId, SIGSTOP); 
     sleep(5); 
     printf("parent: resuming child since it stopped but never really died\n"); 
     kill(childId, SIGCONT); 
     printf("parent: child should be running again where it left off\n"); 
     sleep(5); 

    } 
} 

输出：

parent: child started OK 
infinite child loop ==> 1 
infinite child loop ==> 2 
infinite child loop ==> 3 
infinite child loop ==> 4 
infinite child loop ==> 5 
infinite child loop ==> 6 
parent: stopping child - but letting it live 
parent: resuming child since it stopped but never really died 
parent: child should be running again where it left off 
infinite child loop ==> 7 
infinite child loop ==> 8 
infinite child loop ==> 9 
infinite child loop ==> 10 
infinite child loop ==> 11 
infinite child loop ==> 12