shell练习：写一个脚本实现如下功能：输入一个数字，然后运行对应的一个命令。显示命令如下：*cmd meau** 1--date 2--ls 3--who 4--pwd 当输入1时，会运行date命令，输入2时会运行ls，以此论推

答案：

#! /bin/bash
read -p "*cmd meau** 1--date 2--ls 3--who 4--pwd:" a
if (($a==1));then
date
elif (($a==2));then
ls
elif (($a==3));then
who
elif (($a==4));then
pwd
else
echo "please input 1-4"
fi

答案2：

#! /bin/bash
echo "*cmd meau**"
echo "1--date"
echo "2--ls"
echo "3--who"
echo "4--pwd"
read -p "please input a num:" n
case $n in
    1)
    date
   ;;
    2)
    ls
    ;;
    3)
    who
    ;;
    4)
    pwd
    ;;
    *)
    echo "please input 1-4"
    ;;
esac

答案3：

#! /bin/bash
echo "1-date 2--ls 3--who 4--pwd"
read -p "cmd meau" n
[  $n -eq 1   ] && date
[  $n -eq 2   ] && ls
[  $n -eq 3   ] && who
[  $n -eq 4   ] && pwd