Question

我正在尝试编写一个基本过程控制块的程序，下面的代码显示了我在测试阶段所做的事情，我想知道我们是否可以在遇到一个孩子后重新开始，而不是再次分娩新孩子是的，我们怎么做提前谢谢！
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

当您向子节点发出kill命令时，您可以使用SIGSTOP将其挂起而不会使其死亡，然后使用SIGCONT将其恢复到停止位置。

#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

是否可以恢复被杀害的子进程？

1 个答案: