Bash脚本的变量语法错误(家庭作业)

我试过使用双括号while和ifs
在尝试读取输入之前,我还尝试为输入声明变量
我也试过在班上讨厌几个人,但是大多数人都非常无能为力,只是抄袭别人.

#/!bin/bash
#
#Menunix - Bash
#
#Usage: menunixb
input = "$(1)" 
while [ $input != 5 ]
do
    echo Please choose an option
    echo 1: List Files 
    echo 2: Display today's date and time
    echo 3: Check whether a file is a directory or not
    echo 4: Create a file backup
    echo 5: Quit
    read input
    case $input in
        1) 
            ls
            ;;
        2)
            echo -n Time:
            date +"%T"
            echo Date:
            date +"%D"
            ;;
        3)
            echo What file do you wish to check
            read finput
            if [ -d $finput ] ; then
                echo $finput is a Directory
            elif [ -f $finput ] ; then
            echo $finput is a File
            else
                echo $finput does not exist
                ;;
            4)
                echo Please enter filename to backup
                read binput
                cp $binput{,.bak}
                ;;
            5)
                exit 1
            *)
                echo Please choose a valid input
                exit 1
            esac
        done
#EOF