if (! S_ISREG (st . st_mode)) {
        fprintf (stderr, "%s is not a normal file\n", argv[1]);
        exit(EXIT_FAILURE);
}

// this sleep creates a time gap to change the file and create a symbolic link
sleep (10);

if ((fp = fopen (argv [1], "w")) == NULL) {
        fprintf (stderr, "Can't open\n");
        exit(EXIT_FAILURE);
}

fprintf (fp, "%s\n", argv [2]);
fclose (fp);
fprintf (stderr, "Write Ok\n");