5a_System_calls.c

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#define BUFFER_SIZE 30
int main()
{
  int fd = open("example.txt", O_RDWR), n;
  char buffer[BUFFER_SIZE];
  printf("File discriptor is %d\n", fd);
  if (fd == -1)
  {
    printf("Failed to open file.\n");
    exit(0);
  }
  printf("Reading first 10 characters from file: \n");
  n = read(fd, buffer, 10);
  write(1, buffer, n);
  printf("\nSkipping 5 charecters from current position in the file: \n");
  lseek(fd, 5, SEEK_CUR);
  n = read(fd, buffer, 10);
  write(1, buffer, n);
  printf("\nGoing 10 charecters before the current position in the file: \n");
  lseek(fd, -10, SEEK_CUR);
  n = read(fd, buffer, 10);
  write(1, buffer, n);
  printf("\nGoing to 5th last charecter in the file: \n");
  lseek(fd, -5, SEEK_END);
  n = read(fd, buffer, 5);
  write(1, buffer, n);
  printf("\nGoing to the 3rd charecter in the file: \n");
  lseek(fd, 3, SEEK_SET);
  n = read(fd, buffer, 5);
  write(1, buffer, n);
  return 0;
}