[유닉스/리눅스] 코드 에러 오류좀 확인해주세요 ㅠㅠㅠ

#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
 
int main()
{
 
int filedes;
ssize_t nread;
off_t newpos;
 
char buffer[1024];
char content[] = "UNix hi\n";
 
filedes = open("temp1.txt", O_RDWR);
 
nread = read(filedes,buffer,1024);
 
printf("before : %s",buffer);
 
newpos = lseek(filedes, (off_t)0, SEEK_SET);
 
write(filedes, content, strlen(content));
 
newpos = lseek(filedes, (off_t)0,SEEK_SET);
 
nread = read(filedes,buffer,1024);
 
printf("after :%s",buffer);
close(filedes);
 
}