About Properties
Short description
Describes how to use object properties in PowerShell.
Long description
PowerShell uses structured collections of information called objects to represent the items in data stores or the state of the computer. Typically, you work with object that are part of the Microsoft .NET Framework, but you can also create custom objects in PowerShell.
The association between an item and its object is very close. When you change an object, you usually change the item that it represents. For example, when you get a file in PowerShell, you do not get the actual file. Instead, you get a FileInfo object that represents the file. When you change the FileInfo object, the file changes too.
Most objects have properties. Properties are the data that is associated with an object. Different types of object have different properties. For example, a FileInfo object, which represents a file, has an IsReadOnly property that contains $True if the file the read-only attribute and $False if it does not. A DirectoryInfo object, which represents a file system directory, has a Parent property that contains the path to the parent directory.
Object properties
To get the properties of an object, use the Get-Member cmdlet. For example,
to get the properties of a FileInfo object, use the Get-ChildItem cmdlet
to get the FileInfo object that represents a file. Then, use a pipeline
operator (|) to send the FileInfo object to Get-Member. The
following command gets the PowerShell.exe file and sends it to Get-Member.
The $Pshome automatic variable contains the path of the PowerShell
installation directory.
Get-ChildItem $pshome\PowerShell.exe | Get-Member
The output of the command lists the members of the FileInfo object. Members include both properties and methods. When you work in PowerShell, you have access to all the members of the objects.
To get only the properties of an object and not the methods, use the
MemberType parameter of the Get-Member cmdlet with a value of "property", as
shown in the following example.
Get-ChildItem $pshome\PowerShell.exe | Get-Member -MemberType property
TypeName: System.IO.FileInfo
Name MemberType Definition
---- ---------- ----------
Attributes Property System.IO.FileAttributes Attributes {get;set;}
CreationTime Property System.DateTime CreationTime {get;set;}
CreationTimeUtc Property System.DateTime CreationTimeUtc {get;set;}
Directory Property System.IO.DirectoryInfo Directory {get;}
DirectoryName Property System.String DirectoryName {get;}
Exists Property System.Boolean Exists {get;}
Extension Property System.String Extension {get;}
FullName Property System.String FullName {get;}
IsReadOnly Property System.Boolean IsReadOnly {get;set;}
LastAccessTime Property System.DateTime LastAccessTime {get;set;}
LastAccessTimeUtc Property System.DateTime LastAccessTimeUtc {get;set;}
LastWriteTime Property System.DateTime LastWriteTime {get;set;}
LastWriteTimeUtc Property System.DateTime LastWriteTimeUtc {get;set;}
Length Property System.Int64 Length {get;}
Name Property System.String Name {get;}
After you find the properties, you can use them in your PowerShell commands.
Property values
Although every object of a specific type has the same properties, the values of those properties describe the particular object. For example, every FileInfo object has a CreationTime property, but the value of that property differs for each file.
The most common way to get the values of the properties of an object is to use the dot method. Type a reference to the object, such as a variable that contains the object, or a command that gets the object. Then, type a dot (.) followed by the property name.
For example, the following command displays the value of the CreationTime
property of the PowerShell.exe file. The Get-ChildItem command returns a
FileInfo object that represents the PowerShell.exe file. The command is
enclosed in parentheses to make sure that it is executed before any properties
are accessed. The Get-ChildItem command is followed by a dot and the name of
the CreationTime property, as follows:
(Get-ChildItem $pshome\PowerShell.exe).creationtime
Tuesday, March 18, 2008 12:07:52 AM
You can also save an object in a variable and then get its properties by using the dot method, as shown in the following example:
$a = Get-ChildItem $pshome\PowerShell.exe
$a.CreationTime
Tuesday, March 18, 2008 12:07:52 AM
You can also use the Select-Object and Format-List cmdlets to display the
property values of an object. Select-Object and Format-List each have a
Property parameter. You can use the Property parameter to specify one
or more properties and their values. Or, you can use the wildcard character
(*) to represent all the properties.
For example, the following command displays the values of all the properties of the PowerShell.exe file.
Get-ChildItem $pshome\PowerShell.exe | Format-List -Property *
PSPath : Microsoft.PowerShell.Core\FileSystem::C:\Windows\System3
2\WindowsPowerShell\v1.0\PowerShell.exe
PSParentPath : Microsoft.PowerShell.Core\FileSystem::C:\Windows\System3
2\WindowsPowerShell\v1.0
PSChildName : PowerShell.exe
PSDrive : C
PSProvider : Microsoft.PowerShell.Core\FileSystem
PSIsContainer : False
Mode : -a----
VersionInfo : File: C:\Windows\System32\WindowsPowerShell\
v1.0\PowerShell.exe
InternalName: POWERSHELL
OriginalFilename: PowerShell.EXE.MUI
FileVersion: 10.0.16299.15 (WinBuild.160101.0800)
FileDescription: Windows PowerShell
Product: Microsoft Windows Operating System
ProductVersion: 10.0.16299.15
Debug: False
Patched: False
PreRelease: False
PrivateBuild: False
SpecialBuild: False
Language: English (United States)
BaseName : PowerShell
Target : {C:\Windows\WinSxS\amd64_microsoft-windows-powershell-ex
e_31bf3856ad364e35_10.0.16299.15_none_8c022aa6735716ae\p
owershell.exe}
LinkType : HardLink
Name : PowerShell.exe
Length : 449024
DirectoryName : C:\Windows\System32\WindowsPowerShell\v1.0
Directory : C:\Windows\System32\WindowsPowerShell\v1.0
IsReadOnly : False
Exists : True
FullName : C:\Windows\System32\WindowsPowerShell\v1.0\PowerShell.ex
Extension : .exe
CreationTime : 9/29/2017 6:43:19 AM
CreationTimeUtc : 9/29/2017 1:43:19 PM
LastAccessTime : 9/29/2017 6:43:19 AM
LastAccessTimeUtc : 9/29/2017 1:43:19 PM
LastWriteTime : 9/29/2017 6:43:19 AM
LastWriteTimeUtc : 9/29/2017 1:43:19 PM
Attributes : Archive
Static properties
You can use the static properties of .NET classes in PowerShell. Static properties are properties of class, unlike standard properties, which are properties of an object.
To get the static properties of an class, use the Static parameter of the Get-Member cmdlet.
For example, the following command gets the static properties of the
System.DateTime class.
Get-Date | Get-Member -MemberType Property -Static
TypeName: System.DateTime
Name MemberType Definition
---- ---------- ----------
MaxValue Property static datetime MaxValue {get;}
MinValue Property static datetime MinValue {get;}
Now Property datetime Now {get;}
Today Property datetime Today {get;}
UtcNow Property datetime UtcNow {get;}
To get the value of a static property, use the following syntax.
[<ClassName>]::<Property>
For example, the following command gets the value of the UtcNow static
property of the System.DateTime class.
[System.DateTime]::UtcNow
Properties of scalar objects and collections
The properties of one ("scalar") object of a particular type are often different from the properties of a collection of objects of the same type. For example, every service has as DisplayName property, but a collection of services does not have a DisplayName property.
The following command gets the value of the DisplayName property of the 'Audiosrv' service.
(Get-Service Audiosrv).DisplayName
Windows Audio
Beginning in PowerShell 3.0, PowerShell tries to prevent scripting errors that
result from the differing properties of scalar objects and collections. The
same command returns the value of the DisplayName property of every service
that Get-Service returns.
(Get-Service).DisplayName
Application Experience
Application Layer Gateway Service
Windows All-User Install Agent
Application Identity
Application Information
...
When you submit a collection, but request a property that exists only on single ("scalar") objects, PowerShell returns the value of that property for every object in the collection.
All collections have a Count property that returns how many objects are in the collection.
(Get-Service).Count
176
Beginning in PowerShell 3.0, if you request the Count or Length property of zero objects or one object, PowerShell returns the correct value.
(Get-Service Audiosrv).Count
1
If a property exists on the individual objects and on the collection, only the collection's property is returned.
$collection = @(
[pscustomobject]@{length = "foo"}
[pscustomobject]@{length = "bar"}
)
# PowerShell returns the collection's Length.
$collection.length
2
This feature also works on methods of scalar objects and collections. For more information, see about_Methods.