#include <fcntl.h>
#include <sys/stat.h>
#include <unistd.h>
#define DEFAULT_ID 0

int main()
{
    int data, d;
    size_t sz;
    data=0;
    if ((d = open("bv", O_RDWR | O_CREAT | O_TRUNC, 0644)) < 0) {
        printf("\n\nconfig_write::file error\n\n");
        return;
    }
    printf("sizeof(sz)%d-sizeof(data)%d\n",sizeof(sz), sizeof(data));
    if (write(d, &data, sz)) {
        printf("\n\nconfig_write::  written successfully\n\n");
        close(d);
        return;
    }
    printf("\nexiting...");
    close(d);
}
sample output:
{319}: vi te.c
{320}: cc te.c
{321}: ./a.out
sizeof(sz)4-sizeof(data)4


config_write::  written successfully

{322}: cat bv
{323}