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about_Properties



This is the built-in help made by Microsoft for the document 'about_Properties', in PowerShell version 4 - as retrieved from Windows version 'Microsoft Windows 8.1 Enterprise' PowerShell help files on 2016-06-24.

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TOPIC
about_Properties

SHORT DESCRIPTION
Describes how to use object properties in Windows PowerShell.

LONG DESCRIPTION
Windows 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 Windows 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 Windows 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 Windows 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
Windows 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 Windows 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:

C:\PS> (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:

C:\PS> $a = Get-ChildItem $pshome\PowerShell.exe
C:\PS> $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.


C:\PS> Get-ChildItem $pshome\PowerShell.exe | Format-List -property *



PSPath : Microsoft.PowerShell.Core\FileSystem::C:\Windows\system32\WindowsPowerShell\v1.0\PowerShell.exe
PSParentPath : Microsoft.PowerShell.Core\FileSystem::C:\Windows\system32\WindowsPowerShell\v1.0
PSChildName : PowerShell.exe
PSDrive : C
PSProvider : Microsoft.PowerShell.Core\FileSystem
PSIsContainer : False
VersionInfo : File: C:\Windows\system32\WindowsPowerShell\v1.0\PowerShell.exe
InternalName: POWERSHELL
OriginalFilename: PowerShell.EXE.MUI
File Version: 6.1.6570.1 (fbl_srv_PowerShell(nigels).070711-0102)
FileDescription: PowerShell.EXE
Product: Microsoft® Windows® Operating System
ProductVersion: 6.1.6570.1
Debug: False
Patched: False
PreRelease: False
PrivateBuild: True
SpecialBuild: False
Language: English (United States)

BaseName : PowerShell
Mode : -a---
Name : PowerShell.exe
Length : 160256
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.exe
Extension : .exe
CreationTime : 3/18/2008 12:07:52 AM
CreationTimeUtc : 3/18/2008 7:07:52 AM
LastAccessTime : 3/19/2008 8:13:58 AM
LastAccessTimeUtc : 3/19/2008 3:13:58 PM
LastWriteTime : 3/18/2008 12:07:52 AM
LastWriteTimeUtc : 3/18/2008 7:07:52 AM
Attributes : Archive


STATIC PROPERTIES
You can use the static properties of .NET classes in Windows
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.
Similarly, all collections have a Count property that tells how
many objects are in the collection, but individual objects do not
have a Count property.

Beginning in Windows PowerShell 3.0, Windows PowerShell tries
to prevent scripting errors that result from the differing
properties of scalar objects and collections.

-- If you submit a collection, but request a property
that exists only on single ("scalar") objects, Windows
PowerShell returns the value of that property for every object
in the collection.

-- If you request the Count or Length property of zero objects
or of one object, Windows PowerShell returns the correct value.

If the property exists on the individual objects and on the
collection, Windows PowerShell does not alter the result.

This feature also works on methods of scalar objects and
collections. For more information, see about_Methods.


EXAMPLES

For example, each service has a DisplayName property. The
following command gets the value of the DisplayName property
of the Audiosrv service.

PS C:\>(Get-Service Audiosrv).DisplayName
Windows Audio

However, a collection or array of services does not have a
DisplayName. The following command tries to get the DisplayName
property of all services in Windows PowerShell 2.0.



PS C:\>(Get-Service).DisplayName
PS C:\>

Beginning in Windows PowerShell 3.0, the same command returns
the value of the DisplayName property of every service that
Get-Service returns.

PS C:\>(Get-Service).DisplayName
Application Experience
Application Layer Gateway Service
Windows All-User Install Agent
Application Identity
Application Information
...

Conversely, a collection of two or more services has a Count
property, which contains the number of objects in the collection.

PS C:\>(Get-Service).Count
176

Individual services do not have a Count or Length property, as
shown in this command in Windows PowerShell 2.0.

PS C:\>(Get-Service Audiosrv).Count
PS C:\>

Beginning in Windows PowerShell 3.0, the command returns the
correct Count value.

PS C:\>(Get-Service Audiosrv).Count
1



SEE ALSO
about_Methods
about_Objects
Get-Member
Select-Object
Format-List