external help file | Locale | Module Name | ms.date | online version | schema | title |
---|---|---|---|---|---|---|
Microsoft.PowerShell.Commands.Utility.dll-Help.xml |
en-US |
Microsoft.PowerShell.Utility |
02/03/2023 |
2.0.0 |
Invoke-Expression |
Runs commands or expressions on the local computer.
Invoke-Expression [-Command] <String> [<CommonParameters>]
The Invoke-Expression
cmdlet evaluates or runs a specified string as a command and returns the
results of the expression or command. Without Invoke-Expression
, a string submitted at the command
line is returned (echoed) unchanged.
Expressions are evaluated and run in the current scope. For more information, see about_Scopes.
Caution
Take reasonable precautions when using the Invoke-Expression
cmdlet in scripts. When using
Invoke-Expression
to run a command that the user enters, verify that the command is safe to run
before running it. In general, it is best to design your script with predefined input options,
rather than allowing freeform input.
$Command = "Get-Process"
$Command
Get-Process
Invoke-Expression $Command
Handles NPM(K) PM(K) WS(K) VM(M) CPU(s) Id ProcessName
------- ------ ----- ----- ----- ------ -- -----------
296 4 1572 1956 20 0.53 1348 AdtAgent
270 6 1328 800 34 0.06 2396 alg
67 2 620 484 20 0.22 716 ati2evxx
1060 15 12904 11840 74 11.48 892 CcmExec
1400 33 25280 37544 223 38.44 2564 communicator
...
This example demonstrates the use of Invoke-Expression
to evaluate an expression. Without
Invoke-Expression
, the expression is printed, but not evaluated.
The first command assigns a value of Get-Process
(a string) to the $Command
variable.
The second command shows the effect of typing the variable name at the command line. PowerShell echoes the string.
The third command uses Invoke-Expression
to evaluate the string.
Invoke-Expression -Command "C:\ps-test\testscript.ps1"
"C:\ps-test\testscript.ps1" | Invoke-Expression
These commands use Invoke-Expression
to run a script, TestScript.ps1, on the local computer. The
two commands are equivalent. The first uses the Command parameter to specify the command to run.
The second uses a pipeline operator (|
) to send the command string to Invoke-Expression
.
$Command = 'Get-Process | where {$_.cpu -gt 1000}'
Invoke-Expression $Command
This example runs a command string that is saved in the $Command
variable.
The command string is enclosed in single quotation marks because it includes a variable, $_
, which
represents the current object. If it were enclosed in double quotation marks, the $_
variable
would be replaced by its value before it was saved in the $Command
variable.
$Cmdlet_name = "Get-ComputerInfo"
$Example_number = 1
$Example_code = (Get-Help $Cmdlet_name).examples.example[($Example_number-1)].code
Invoke-Expression $Example_code
This command retrieves and runs the first example in the Get-EventLog
cmdlet Help topic.
To run an example of a different cmdlet, change the value of the $Cmdlet_name
variable to the name
of the cmdlet. And, change the $Example_number
variable to the example number you want to run. The
command fails if the example number is not valid.
Note
If the example code from the help file has output in the example, PowerShell attempts to run the output along with the code and an error will be thrown.
Specifies the command or expression to run. Type the command or expression or enter a variable that contains the command or expression. The Command parameter is required.
Type: System.String
Parameter Sets: (All)
Aliases:
Required: True
Position: 0
Default value: None
Accept pipeline input: True (ByValue)
Accept wildcard characters: False
This cmdlet supports the common parameters: -Debug, -ErrorAction, -ErrorVariable, -InformationAction, -InformationVariable, -OutVariable, -OutBuffer, -PipelineVariable, -Verbose, -WarningAction, and -WarningVariable. For more information, see about_CommonParameters.
You can pipe a string representing the expression to invoke to this cmdlet. Use the $Input
automatic variable to represent the input objects in the command.
You can pipe an object representing the expression to invoke to this cmdlet. Use the $Input
automatic variable to represent the input objects in the command.
This cmdlet returns no output of its own, but the invoked command may return output.
PowerShell includes the following aliases for Invoke-Expression
:
- All platforms:
iex
In most cases, you invoke expressions using PowerShell's call operator and achieve the same results. The call operator is a safer method. For more information, see about_Operators.