#define _FILE_OFFSET_BITS 64

#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>


static struct flock lock = {
        F_WRLCK,
        SEEK_CUR,
        0L,
        0L
    };

int main ()
{
    static int fd;

    fd = open("dummy.lock", O_RDWR | O_CREAT, 0644);
    if (fd < 0) {
        perror("cannot open lockfile");
        return 1;
    }

    if (fcntl(fd, F_SETLKW, &lock) == -1) {
        perror("cannot obtain exclusive lock");
        return 2;
    }

    pause();

    close(fd);
    return 0;
}