In Powershell, what is the difference between -Property and -ExpandProperty?

Running the cmdlets, the outputs are slightly different, and I'm just trying to understand the difference between the two cmdlets and why you would use one over the other.

Example:

Get-Date | Select -Property DayOfWeek

Output:

DayOfWeek
---------
Saturday

Get-Date | Select -ExpandProperty DayOfWeek
Saturday

1 Answer

Intro

You can inspect any object in Powershell by feeding it to Format-List cmdlet:

PS> Get-Date | Format-List
DisplayHint : DateTime
Date : 2018-10-21 0:00:00
Day : 21
DayOfWeek : Sunday
DayOfYear : 294
Hour : 18
Kind : Local
Millisecond : 28
Minute : 38
Month : 10
Second : 36
Ticks : 636757439160281486
TimeOfDay : 18:38:36.0281486
Year : 2018
DateTime : 21 жовтня 2018 р. 18:38:36

Then, you can change the object, eg. create the new object with subset of properties of original object. You do this using Select-Object cmdlet and with the list of required properties in -Property parameter.

Select-Object has default alias Select, but I suggest that while learning Powershell and exchanging your code with external parties, eg. Superuser.com you do not use aliases, but only full names of cmdlets for the sake of clarity

Answer

• Get-Date | Select-Object -Property DayOfWeek will create object which has only one property DayOfWeek of the object returned by Get-Date

• Get-Date | Select-Object -ExpandProperty DayOfWeek will return the String with the content of DayOfWeek property