my $chld_flag = 0;

    $SIG{'CHLD'} = sub { $chld_flag = 1; };
    $SIG{'ALRM'} = 'IGNORE';

    while (1) {
        # Check child processes
        #   Includes using waidpid() to clean up after child processes

        # Display status

        # Get user commands
        my $cmd = '';
        eval {
            # Allow interrupts by alarms and 'child' events
            local $SIG{'CHLD'} = sub { die("CHLD EVENT\n"); };
            local $SIG{'ALRM'} = sub { die("ALRM EVENT\n"); };

            alarm(10);

            if (! $chld_flag) {
                $cmd = <STDIN>;
            }
        };
        alarm(0);
        $chld_flag = 0;

        # Process user command, if any
        #   Such as launch child processes
    }