PowerShell, call script with parameter without a value, like a script with options

Question

Is it possible to call a PowerShell script with options? Like a parameter without a value.

For instance I currently use:

param (
    $lastmonth=0
);

in the script. Now I can use the call

script.ps1 -lastmonth 1

or

script.ps1

and use $lastmonth for controlling the flow.

But I'd like to have the calls like

script.ps1 -lastmonth

and

script.ps1

and control the flow depending on whether -lastmonth was given, or not.

RB. · Accepted Answer · 2014-01-31 13:03:46Z

81

Set the type of your parameter to [switch], e.g.

param (
    [switch]$lastmonth
);

EDIT: Note that the variable will be a boolean. You can test it like:

if ($lastMonth) {
    Write-Host "lastMonth is set."
}
else {
    Write-Host "lastMonth is not set."
}

(thanks Chris)

edited Jan 31, 2014 at 13:03

answered Jan 31, 2014 at 12:18

RB.

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3 Comments

Christian Over a year ago

... and then it's a boolean variable.

RB. Over a year ago

@Chris Lol, yep, should probably have mentioned that! I'll update my answer :)

EkriirkE Over a year ago

It seems you have to explicitly use $lastMonth.IsPresent for unary conditions, as it is not a true boolean. if ($lastMonth) works $lastMonth?x:y does not, but $lastMonth.IsPresent?x:y does. PS 7.3.9

pavol.kutaj · Accepted Answer · 2021-03-02 07:51:40Z

3

This is called a switch parameter. Checkout out the official documentation @ Microsoft Docs.

answered Mar 2, 2021 at 7:51

pavol.kutaj

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