1 #include "apue.h" 2 #include <dirent.h> 3 int 4 main(int argc, char *argv[]) 5 { 6     DIR            *dp; 7     struct dirent    *dirp; 8     if (argc != 2) 9         err_quit("usage: ls directory_name");10     if ((dp = opendir(argv[1])) == NULL)11         err_sys("can‘t open %s", argv[1]);12     while ((dirp = readdir(dp)) != NULL)13         printf("%s\n", dirp->d_name);14     closedir(dp);15     exit(0);16 }