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

int main(int argc, char *argv[]) {
    if (argc != 3) {
        fprintf(stderr, "Usage: %s shm_name number\n", argv[0]);
        exit(EXIT_FAILURE);
    }

    int number = atoi(argv[2]);

    int shm_fd = shm_open(argv[1], O_CREAT | O_RDWR, 0666);
    ftruncate(shm_fd, sizeof(int));

    int *addr = mmap(NULL, sizeof(int), PROT_READ | PROT_WRITE, MAP_SHARED, shm_fd, 0);
    if (addr == MAP_FAILED) {
        perror("mmap");
        exit(EXIT_FAILURE);
    }

    *addr = number;

    getchar();

    munmap(addr, sizeof(int));
    close(shm_fd);
    shm_unlink(argv[1]);
    exit(EXIT_SUCCESS);
}