Shell脚本 - 分叉进程

Question

我已经完成了一项任务，即让某个程序显示menu类似的用户界面，并执行简单的任务，例如ls who和top然后进行shell脚本分叉到子进程，然后从新创建的子进程运行后续命令。但我不懂C ++，而是想使用Shell脚本。我到目前为止的代码如下：

#!/bin/bash
trap '' 2 #trapping the CTRL + C command so users are forced to use number 4 to stop.
while true #while statement for the return function
do
        clear #clears the screen so it doesn't look messy when looping
        echo "=============================================="
        echo "|        Outside The CPU Shell Script        |"
        echo "=============================================="
        echo "| Enter 1 for Who                            |"
        echo "| Enter 2 for Ls                             |" #basic echos to show the menu
        echo "| Enter 3 for Top                            |"
        echo "| Enter 4 to exit                            |"
        echo "=============================================="
        echo -e "\n" #returns a new line
        echo -e "Enter your selection \c |" #prompts to select while suppressing output
        read answer #reads input and stores value in variable named answer
        case "$answer" in # a case statement (like if/elif statement) using variable answer
                1) who ;; #actual command that is used
                2) ls ;;
                3) top ;;
                4) exit ;;
        esac #ending statement for the case
        echo -e "Enter return to continue \c" #the return statement to bring back to main menu
        read input #read enter and store in variable input
done

如何在此脚本调用fork时进行处理，然后控制它创建的子进程？

谢谢，