c - fork 和执行

Question

我正在尝试使用 fork 和 execlp 的程序，其中父地址空间被替换为“ls”命令。

#include<stdio.h>
main()
{
    int pid,j=10,fd;
    pid=fork();
    if(pid==0)
    {
        printf("\nI am the child\n");
        execlp("/bin/ls","ls",NULL);
        printf("\nStill I am the child\n");

    }
    else if (pid > 0)
    {
        printf("\n I am the parent\n");
        wait();
    } 
}

当我执行程序时最后一行child

printf("\nStill I am the child\n");

未打印。为什么？

Answer 1

exec 系列函数在成功时不返回。

http://pubs.opengroup.org/onlinepubs/009604499/functions/exec.html

The exec family of functions shall replace the current process image with a new process image. The new image shall be constructed from a regular, executable file called the new process image file. There shall be no return from a successful exec, because the calling process image is overlaid by the new process image.

If one of the exec functions returns to the calling process image, an error has occurred; the return value shall be -1, and errno shall be set to indicate the error.