Tell the kernel to drop the page cache

drop_caches.c

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

int main(int argc, char **argv) {
  sync();

  int fd = open("/proc/sys/vm/drop_caches", O_WRONLY);

  if (fd == -1) {
    perror("open()");
    return 1;  }

  ssize_t result = write(fd, "1", 1);

  if (result == -1) {
    perror("write()");
    return 2;
  }

  if (close(fd) == -1) {
    perror("close()");
    return 3;
  }

  return 0;
}