#include<stdio.h>
#include<unistd.h>
#include<fcntl.h>
#include<sys/stat.h>
int main()
{
int fd1 = 0, fd2 = 0;
char buf[50];
fd1 = open("t12.txt", O_RDWR, 0);
if(fd1 < 0)
{
printf("File open error\n");
return 0;
}
fd2 = dup(fd1);
read(fd1, buf, 12);
lseek(fd2, 0L, SEEK_END);
write(fd2, buf, 12);
return 0;
}







#include<stdio.h>
#include<fcntl.h>
#include<unistd.h>
#include<dirent.h>
#include<sys/stat.h>
int main
{
DIR *d;
struct dirent *dir;
d = opendir(".");
if (d)
{
while ((dir = readdir(d)) != NULL)
{
printf("%s\n",dir->d_name);
}
closedir(d);
}
return(0);
}