Question

1) I have a struct and need to write it to a file using the write() system call, NOT fwrite(). Is this possible?

2) After writing the structure to the file, I need to read another file, and write it to end of the file the structure is now written in.

Any help would be appreciated.

Answer 1

this will write your structure to a file.

int fd = open(file, O_WRONLY);
struct my_struct a;

write(output, &a, sizeof(struct my_struct));

For the other file, simply open it, read it’s content in a loop, and write it to the previous.

int fd2 = open(otherfile, O_RDONLY);
int readret;
char buf[4096];

while ((readret = read(fd2, buf, sizeof(buf) != 0) {
  write(fd, buf, readret); 
}

remember to test every write/read result, (as mention in the comment), and handle those errors.