1fork ，fork的子进程和父进程同时运行，运行顺序不确定

2 vfork先运行子进程，再运行父进程

3 fork 运行如下

test@ubuntu:~/test$ ./fort 
i am father :15503 
i am child :15504 
test@ubuntu:~/test$ 

fork程序

#include<unistd.h>
#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <math.h>

int main(void)
{
    pid_t child;
    /*创建子程序*/
    if((child=fork())==-1)
    {
        printf("fork error :%d \n",strerror(errno));
        exit(1);
        
    }else if( 0 == child)/*子进程*/
    {
        printf("i am child :%d \n",getpid());
        exit(0);
        
    }else 
    {
        printf("i am father :%d \n",getpid());
        exit(0);
        
    }

}

4.vfork,运行如下：

test@ubuntu:~/test$ gcc -o vf vfork_test.c 
test@ubuntu:~/test$ ./vf
child process start...
i am child 15481
i am father :15480 
test@ubuntu:~/test$ 

代码

#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>

int main(void)
{
    
    pid_t child;
    
    
    if((child = vfork())==-1)
    {
        printf("vfork error :%d \n",strerror(errno));
        exit(1);
        
    }else if(0==child)/*子进程优先运行*/
    {
        printf("child process start...\n");
        sleep(2);
        printf("i am child %d\n",getpid());
        exit(0);
    }else 
    {
        printf("i am father :%d \n",getpid());
        exit(0);
    }
    
}