PowerShell:: 输入一个列表作为参数

Question

In the same directory I have 2 files:

• Servers.txt (which contains a list of server names)
• test.ps1 (which is my PowerShell script)

my test.ps1 contains this code:

param(
    $Servers = get-content -Path "Servers.txt"
    ForEach($Server in $Servers) {
        $instance = $Server}
)

As soon as I try to run it I incur in the error:

At C:\test.ps1:2 char:15
+     $Servers = get-content -Path "Servers.txt"
+               ~
Missing expression after '='.
At C:\test.ps1:2 char:13
+     $Servers = get-content -Path "Servers.txt"
+             ~
Missing ')' in function parameter list.
At C:\test.ps1:5 char:1
+ )
+ ~
Unexpected token ')' in expression or statement.
    + CategoryInfo          : ParserError: (:) [], ParseException
    + FullyQualifiedErrorId : MissingExpressionAfterToken

Which is very odd as the code is so simple.

The goal is to input a list of server names that I'm later going to parse.

Any help?

Answer 1

To use output from a command (as opposed to an expression ) as a parameter variable's default value, you must convert it to an expression with (...) , the grouping operator :

# Parameter declarations
param(
    $Servers = (get-content -Path "Servers.txt")
)

# Function body.
ForEach($server in $Servers) {
  $instance = $server
}

Note: Use of $(...) , the subexpression operator , is only required if the default value must be determined via multiple commands (or whole statement (s), such as foreach or while loop).