linux下创建进程的练习

/*start from the very beginning,and create greatness
@name:Chuangwei Lin
@E-mail:[e-mail]
@brief:get pid and get ppid
*/
#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
// int main(int argc, char const *argv[])
// {
//     pid_t pid,ppid;
//     //get the pid and ppid(parent process ID)
//     pid = getpid();
//     ppid = getppid();
//     printf("the pid is :%d\n",pid);
//     printf("the ppid is :%d\n",ppid );
//     return 0;
// }
/*use fork() to create a process*/
// int main(int argc, char const *argv[])
// {
//     pid_t pid;
//     //
//     pid = fork();

//     if (-1 == pid )
//     {
//         printf("process create fail!\n");
//         return -1;
//     }
//     else if ( pid == 0)
//     {
//         //code in child process
//         printf("child process:fork return :%d,ID :%d,parent process ID:%d\n", pid,getpid(),getppid());
//     }
//     else
//     {
//         //code in parent process
//         printf("parent process:fork return :%d,ID :%d,parent process ID:%d\n",pid,getpid(),getppid());
//     }
//     return 0;
// }
/*use pipe to send simple messsage*/
#include <stdlib.h>
#include <string.h>
int main(int argc, char const *argv[])
{
    int result=-1;//the result of pipe
    int fd[2],nbytes;//file descriptor,and the number of return bytes
    pid_t pid;
    char string[]="Hello ,I am Lin";
    char readbuffer[80];
    //the file descriptor 1 is used to  write ,2 is used to read
    int *write_fd=&fd[1];
    int *read_fd=&fd[0];

    result=pipe(fd);//create a pipe
    if (-1==result)
    {
        printf("create pipe fail\n");
        return -1;
    }
     pid =fork();
     if (-1==pid)
     {
         printf("create process fail\n");
         return -1;
     }
     if (0==pid)//child process
     {
         close(*read_fd);
         result=write(*write_fd,string,strlen(string));
         //write message to pipe
     }
     else//parent process
     {
        close(*write_fd);
        nbytes=read(*read_fd,readbuffer,sizeof(readbuffer));
        //read message from pipe
        printf("receive %d bytes from pipe:%s\n",nbytes,readbuffer );
     }

    return 0;
}