getpid/getppid系统调用

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用法： 
#include <sys/types.h>
#include <unistd.h>

pid_t getpid(void);
pid_t getppid(void);

例子：

#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>

int main(void)
{

pid_t pid;
printf(“Before fork …/n”);

switch(pid = fork()) {

   case -1:
    printf(“Fock call fail/n”);
    exit(1);
   
   case 0:
    printf(“The pid of child is: %d/n”, getpid());
    printf(“The pid of child’s parent is: %d/n”, getppid());
    printf(“Child exiting…/n”);
    exit(0);
  
   default:
    printf(“The pid of parent is: %d/n”, getpid());
    printf(“the pid of parent’s child is: %d/n”, pid);
}

printf(“After fork, program exiting…/n”);
exit(0);
}