Sends the signal SIGALRM (defined in the <signal.h> header file)
    to the invoking process after the number of seconds indicated by
    its argument has elapsed.

    Format

      #include  <unistd.h>

      unsigned int alarm  (unsigned int seconds); (ISO POSIX-1)

      int alarm  (unsigned int seconds); (Compatibility)

  Additional Information (explode) :

• Argument
• Description
• Return Value