Switch-parameter-with-value

Switch parameter with value

If a script has a switch parameter then it is tricky to invoke it with a specified switch value by PowerShell.exe. Also, it is only possible with Command, not File.

The script Script1.ps1 has the switch parameter Option. The switch value ($true or $false) is defined by the variable $useOption. How to invoke the script with this value specified?

In the same session this done as:

.\Script1.ps1 -Option:$useOption

How to invoke the script as a new process?

PowerShell -Command

The script Test-1-command-fails.ps1 tries to use the similar syntax:

PowerShell .\Script1.ps1 -Option:$useOption

It fails. The arguments are converted to text and the actual command is:

.\Script1.ps1 -Option:True

It turns out strings True or False cannot be converted to a switch value. This may look strange because they are converted to [bool] fine:

[bool]'True'

But [switch] ([System.Management.Automation.SwitchParameter) is not designed to be created from a string, even from True or False.

The script Test-2-command-works.ps1 uses the syntax which works:

PowerShell .\Script1.ps1 -Option:`$$useOption

The above arguments are converted to valid commands:

.\Script1.ps1 -Option:$True
.\Script1.ps1 -Option:$False

PowerShell -File

Fixed in v6.0.0-beta.5

There is no way to pass a switch value in a script invoked by File. It is expected that not all data can be passed in another process via parameters. But switch parameters are so basic that such a way ideally should exist.

The workaround for a single switch is relatively simple:

if ($useOption) {
    PowerShell -File Script1.ps1 -Option
}
else {
    PowerShell -File Script1.ps1
}

But for two or more switches defined by variables the code becomes too complex for such a simple task.

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• Stack Overflow question
• Allow passing $true/$false as a parameter to scripts using powershell.exe -File
• Microsoft Connect 742084