[root@localhost unix_env_advance_prog]# cat prog1-.c

#include "apue.h"

#include <dirent.h>

int main(int argc, char *argv[])

{

        DIR             *dp;

        struct dirent   *dirp;

        if(argc != )

                err_quit("Usage: ls directory_name");

        if((dp = opendir(argv[]))==NULL)

                err_sys("can't open %s", argv[]);

        while((dirp = readdir(dp)) != NULL)

                printf("%s\n", dirp->d_name);

        closedir(dp);

        exit();

}