使用输出运算符在powershell中命名.txt文件

Question

I am trying to create a variable that will name a text file using the output operator in powershell. The first example is what would normally be done without the variable (which works), and the second is going to be the way that I am trying to do it (which is not working).

Example I:

"hello" >> janice.txt

As we can see, the result of Example I would be a text file called janice.txt

Example II.

$i = "janice"
"hello" >> $i.txt

The result that I would expect from example II would be a text file named: janice.txt just like the first example since the variable $i is storing the string "janice".

Powershell is executing the command with no errors, but no .txt file is created. I'm trying to figure out why It's not working and if anything, is it completely irrelevant.

This is my first time asking a question so I apologize in advance if it is wordy and rather vague.

Answer 1

Obvious after someone else pointed it out to me; $i.txt is doing a property lookup. Like $i.Length or $file.FullName .

Since there is no property called .txt , the lookup returns $null and your write goes nowhere like doing "hello" > $null .

Proof: Running the PowerShell tokenizer against the two pieces of code to see how they are processed internally:

[System.Management.Automation.PSParser]::Tokenize('"a" > janice.txt', [ref]$null)  | 
    Select-Object Content, Type |
    Format-List


Content : a
Type    : String

Content : >
Type    : Operator

Content : janice.txt
Type    : CommandArgument

A redirect operator, with a string on the left and a command argument on the right. Vs.

[System.Management.Automation.PSParser]::Tokenize('"a" > $i.txt', [ref]$null) |
    Select-Object Content, Type |
    Format-List


Content : a
Type    : String

Content : >
Type    : Operator

Content : i
Type    : Variable

Content : .
Type    : Operator

Content : txt
Type    : Member

A string and a redirect operator, with (a variable, the . operator and 'txt' as a member) on the right.

Answer 2

Try this:

"hello" >> "$i.txt"

:)