Select-Object

Syntax

Select-Object
      [[-Property] <Object[]>]
      [-InputObject <PSObject>]
      [-ExcludeProperty <String[]>]
      [-ExpandProperty <String>]
      [-Unique]
      [-Last <Int32>]
      [-First <Int32>]
      [-Skip <Int32>]
      [-Wait]
      [<CommonParameters>]

Select-Object
      [[-Property] <Object[]>]
      [-InputObject <PSObject>]
      [-ExcludeProperty <String[]>]
      [-ExpandProperty <String>]
      [-Unique]
      [-SkipLast <Int32>]
      [<CommonParameters>]

Select-Object
      [-InputObject <PSObject>]
      [-Unique]
      [-Wait]
      [-Index <Int32[]>]
      [<CommonParameters>]

Description

The Select-Object cmdlet selects specified properties of an object or set of objects. It can also select unique objects, a specified number of objects, or objects in a specified position in an array.

To select objects from a collection, use the First , Last , Unique , Skip , and Index parameters. To select object properties, use the Property parameter. When you select properties, Select-Object returns new objects that have only the specified properties.

Beginning in Windows PowerShell 3.0, Select-Object includes an optimization feature that prevents commands from creating and processing objects that are not used. When you include a Select-Object command with the First or Index parameter in a command pipeline, Windows PowerShell stops the command that generates the objects as soon as the selected number of objects is generated, even when the command that generates the objects appears before the Select-Object command in the pipeline. To turn off this optimizing behavior, use the Wait parameter.

Examples

Example 1: Select objects by property

PS C:\> Get-Process | Select-Object -Property ProcessName, Id, WS

This command creates objects that have the Name, ID, and working set (WS) properties of process objects.

Example 2: Select objects by property and format the results

PS C:\> Get-Process Explorer | Select-Object -Property ProcessName -ExpandProperty Modules | Format-List



ProcessName       : 00THotkey

Size              : 256

Company           : TOSHIBA Corporation

FileVersion       : 1, 0, 0, 27

ProductVersion    : 6, 2, 0, 0

Description       : THotkey

Product           : TOSHIBA THotkey

ModuleName        : 00THotkey.exe

FileName          : C:\WINDOWS\system32\00THotkey.exe

BaseAddress       : 4194304

This command gets information about the modules used by the processes on the computer. It uses Get-Process cmdlet to get the process on the computer. It uses the Select-Object cmdlet to create new objects with only the selected properties. The command uses the Property parameter of the Select-Object cmdlet to select the process names. Because the Modules property contains a ModuleProcess object that has many properties, the command uses the ExpandProperty parameter to get the properties of the objects in the Modules property of each process. The command uses the Format-List cmdlet to display the name and modules of each process in a list.

Example 3: Select processes using the most memory

PS C:\> Get-Process | Sort-Object -Property WS | Select-Object -Last 5



Handles  NPM(K)    PM(K)      WS(K) VS(M)   CPU(s)     Id ProcessName

-------  ------    -----      ----- -----   ------     -- -----------

2866     320       33432      45764   203   222.41   1292 svchost

577      17        23676      50516   265    50.58   4388 WINWORD

826      11        75448      76712   188    19.77   3780 Ps

1367     14        73152      88736   216    61.69    676 Ps

1612     44        66080      92780   380   900.59   6132 INFOPATH

This command gets the five processes that are using the most memory. The Get-Process cmdlet gets the processes on the computer. The Sort-Object cmdlet sorts the processes according to memory (working set) usage, and the Select-Object cmdlet selects only the last five members of the resulting array of objects.

The Wait parameter is not required in commands that include the Sort-Object cmdlet because Sort-Object processes all objects and then returns a collection. The Select-Object optimization is available only for commands that return objects individually as they are processed.

Example 4: Select the name and start day of processes

PS C:\> Get-Process | Select-Object -Property ProcessName,@{Name="Start Day"; Expression = {$_.StartTime.DayOfWeek}}



ProcessName  StartDay

----         --------

alg          Wednesday

ati2evxx     Wednesday

ati2evxx     Thursday

...

This command gets the name and start day of the processes running on a computer.

The command uses the Get-Process cmdlet to get the processes on the computer. It passes the processes to the Select-Object cmdlet, which creates objects that have only the ProcessName parameter and a calculated property named Start Day. The Start Day property is added by using a hash table with Name and Expression keys. The value of the Expression key is a script blocks that gets the StartTime property of each process and the DayofWeek property of the StartTime.

Example 5: Select unique characters from an array

PS C:\> "a","b","c","a","a","a" | Select-Object -Unique



a

b

c

This command uses the Unique parameter of Select-Object to get unique characters from an array of characters.

Example 6: Select newest and oldest events in the event log

PS C:\> $A = Get-Eventlog -Log "Windows PowerShell"

PS C:\> $A | Select-Object -Index 0, ($A.count - 1)

These commands gets the first (newest) and last (oldest) events in the Windows PowerShell event log.

The command uses the Get-EventLog cmdlet to get all events in the Windows PowerShell log. It saves them in the $A variable.

The second command uses a pipeline operator (|) to send the events in $A to the Select-Object cmdlet. The Select-Object command uses the Index parameter to select events from the array of events in the $A variable. The index of the first event is 0. The index of the last event is the number of items in $A minus 1.

Example 7: Select all but the first object

PS C:\> New-PSSession -ComputerName (Get-Content Servers.txt | Select-Object -Skip 1)

This command creates a new PSSession on each of the computers listed in the Servers.txt files, except for the first one.

This command uses the Select-Object cmdlet to select all but the first computer in a list of computer names. The resulting list of computers is set as the value of the ComputerName parameter of the New-PSSession cmdlet.

Example 8: Rename files and select several to review

PS C:\> Get-ChildItem *.txt -ReadOnly | Rename-Item -NewName {$_.BaseName + "-ro.txt"} -PassThru | Select-Object -First 5 -Wait

This command adds a -ro suffix to the base names of text files that have the read-only attribute and then displays the first five files so the user can see a sample of the effect.

The command uses the ReadOnly dynamic parameter of the Get-ChildItem for FileSystem cmdlet to get read-only files. It uses a pipeline operator (|) to send the files to the Rename-Item cmdlet, which renames the file. It uses the Passthru parameter of Rename-Item to send the renamed files to the Select-Object cmdlet, which selects the first five for display.

The Wait parameter of Select-Object prevents Windows PowerShell from stopping the Get-ChildItem cmdlet after it gets the first five read-only text files. Without this parameter, only the first five read-only files would be renamed.

Optional Parameters

Inputs

System.Management.Automation.PSObject

You can pipe any object to Select-Object .

Outputs

System.Management.Automation.PSObject

Notes

• You can also refer to the Select-Object cmdlet by its built-in alias, select . For more information, see about_Aliases.
• The optimization feature of Select-Object is available only for commands that write objects to the pipeline as they are processed. It has no effect on commands that buffer processed objects and write them as a collection. Writing objects immediately is a cmdlet design best practice. For more information, see Write Single Records to the Pipeline in Strongly Encouraged Development Guidelines in the MSDN library.

Related Links

• Group-Object
• Sort-Object