Programming

#include <unistd.h>
#define DEFAULT_ID 0

int main()
{
    int d, n=0;
    int sz, data=0;
    char fn[256];
    char *bv;
    snprintf(fn, 256, "bv", DEFAULT_ID);
    bv=fn;
    printf("%s\n", bv);
    if ((d = open(bv, O_RDWR | O_CREAT | O_TRUNC, 0644)) < 0) {
        printf("\n\nconfig_write::file error\n\n");
        return;
    }

    if ((n = write(d,(char*) data, sz)) != sz) {
        printf("\n\nconfig_write::  written successfully\n\n");
        close(d);
        unlink(fn);
        return;
    }
    printf("\n\nconfig_write:: (%d)\n\n", n);
    close(d);
}
output::
{245}: cc te.c
{246}: ./a.out
bv


config_write::  written successfully

{247}: 
{247}: ls -lrt | tail
-rwxrwxr-x   1 team   4232329 Dec  3 02:22 iswitchd.bv.n
-rw-r--r--   1 team     29471 Dec  3 20:44 config.txt
drwxrwxr-x   2 team      4096 Dec  4 01:14 ConfigSpecs.bak
drwxrwxr-x  28 team      4096 Dec  4 02:47 dist.config.up.dow
-rw-r--r--   1 team     29667 Dec  4 02:59 config.new
-rw-r--r--   1 team     29667 Dec  4 21:00 config2
-rw-r--r--   1 team     29667 Dec  4 22:59 config3
-rw-r--r--   1 team     33293 Dec  5 00:10 fc
-rw-rw-r--   1 team       603 Dec  9 22:04 te.c
-rwxrwxr-x   1 team      5480 Dec  9 22:05 a.out

sz = sizeof(data);
write(d, &data, sz);

sz = sizeof(data);

#include <stdio.h>

#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}