最近做一些脚本自动化的事情，发现一个很有意思的东西，如下，如果用户账户包含了$符号，就会抛出一个“User cannot be found”的异常。

New-SPSite $CommunityUrl -OwnerAlias "ASIAPACIFIC`\$ExSquareDEV001" -Name "$CommunityName" -Template "STS#0" -ContentDatabase $CommunityDatabase New-SPSite : User cannot be found.

上MSDN搜索了一下，发现了一篇文章讲述到了这个原因：

Quotation Marks in Windows PowerShell

First, let's review the basic distinction between single and double quotation marks in the Windows PowerShell language. It concerns the interpretation of variables.

• Double quotes. When a command or expression that includes variables is enclosed in double quotes ("), the variables are replaced by their values before the command is executed.

• Single quotes. When a command or expression that includes variables is enclosed in single quotes ('), the variables are not replaced by their values. Instead, they are interpreted literally.

There's actually a lot more to it – nested quotes and doubled quotes and escaped quotes and quotes in here-strings -- but these are the basics. For the rest, at the Windows PowerShell prompt, type:

• get-help about_quoting_rules

大意是由于$是PowerShell变量的标志符号，所以不同的引号会做不同的处理。

双引号内的PowerShell变量会先计算出值，然后输出。

单引号内的PowerShell变量作为字符串直接输出。

看下面的一个示例：

使用双引号赋值，

变量赋值：$ExSquareServiceAccount = "ASIAPACIFIC\$ExSquareDEV001"

输出变量值：ASIAPACIFIC\

由于后面的认成了变量，而并没有赋值，这个时候就为空，输出就是前面的字符串了。

如果使用单引号，

变量赋值：$ExSquareServiceAccount = 'ASIAPACIFIC\$ExSquareDEV001'

输出变量值：ASIAPACIFIC\$ExSquareDEV001

整个字符串不会进行变量替换，直接输出。