Add code to the program in Example 60-4 (is_echo_sv.c) to place a limit on the number of simultaneously executing children.

Sometimes, it may be necessary to write a socket server so that it can be invoked either directly from the command line or indirectly via inetd. In this case, a command-line option is used to distinguish the two cases. Modify the program in Example 60-4 so that, if it is given a -i command-line option, it assumes that it is being invoked by inetd and handles a single client on the connected socket, which inetd supplies via STDIN_FILENO. If the -i option is not supplied, then the program can assume it is being invoked from the command line, and operate in the usual fashion. (This change requires only the addition of a few lines of code.) Modify /etc/inetd.conf to invoke this program for the echo service.