shell 单引号以及双引号

#!/bin/bash
a=23
echo '$a'
echo "$a"

your_name='runoob'
str="Hello, I know you are "$your_name"! 
"
echo -e $str
echo $str

输出

bogon:Desktop macname$ ./test.sh 
$a
23
Hello, I know you are "runoob"! 

Hello, I know you are "runoob"! 

参考：

https://www.runoob.com/linux/linux-shell-variable.html