Invoke-Expression

Run a PowerShell expression. Accepts a string to be executed as code. It is essential that any user input is carefully validated.

Syntax
      Invoke-Expression [-command] string [CommonParameters]

Key
   -command string
       A literal string (or variable that contains a string) that is a
       valid PowerShell expression.

   CommonParameters:
       -Verbose, -Debug, -ErrorAction, -ErrorVariable, -WarningAction, -WarningVariable,
       -OutBuffer -OutVariable.

Standard Aliases for Invoke-Expression: iex

If the result of the expression is an empty array, invoke-expression will output $null

Invoke-Expression can be used to perform string expansion but if the string is supplied by an end-user you need to ensure that it does not contain malicious code/expressions.

This usage (calling a script block) is similar to

Using Invoke-Expression to run a set of commands is similar to using the & call operator but has a key difference in that invoke-expression does not create an additional scope, so any changes to variables made by the script block will remain visible.

Example

Create variables named $sorting and $MyExpr and use them to store the text of an expression, then use invoke-expression to actually run the expression:

PS C:\> $sorting = "sort-object Name"
PS C:\> $myExpr = "get-process | $sorting"
PS C:\> invoke-expression $myExpr


“Innovation is the distinction between a leader and a follower” ~ Steve Jobs

Related:

Get-Command - Retrieve basic information about a command.
Invoke-Command - Run commands on local and remote computers.
Invoke-Expression - Run a PowerShell expression.
Invoke-Item - Invoke an executable or open a file (START)
Invoke-History - Invoke a previously executed Cmdlet.
Start-Process - Start one or more processes, optionally as a specific user.
Trace-Command - Trace an expression or command.
--% - Stop parsing input as PowerShell commands.
. (source) - Run a command script in the current shell (persist variables and functions.)
& (call) - Run a command script.


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