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Select-Object

Selects objects or object properties.
Select-Object [[-Property] <Object[]>] [-ExcludeProperty <String[]>] [-ExpandProperty <String>] [-First <Int32>][-InputObject <PSObject>] [-Last <Int32>] [-Skip <Int32>] [-Unique] [-Wait] [<CommonParameters>]
Select-Object [[-Property] <Object[]>] [-ExcludeProperty <String[]>] [-ExpandProperty <String>] [-InputObject<PSObject>] [-SkipLast <Int32>] [-Unique] [<CommonParameters>]
Select-Object [-Index <Int32[]>] [-InputObject <PSObject>] [-Unique] [-Wait] [<CommonParameters>]

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.

Parameters

-ExcludeProperty <String[]>

  • Default value is None
  • Accepts pipeline input False

Specifies the properties that this cmdlet excludes from the operation. Wildcards are permitted. This parameter is effective only when the command also includes the Property parameter.

-ExpandProperty <String>

  • Default value is None
  • Accepts pipeline input False

Specifies a property to select, and indicates that an attempt should be made to expand that property. Wildcards are permitted in the property name.

For example, if the specified property is an array, each value of the array is included in the output. If the property contains an object, the properties of that object are displayed in the output.

-First <Int32>

  • Default value is False
  • Accepts pipeline input False

Gets only the specified number of objects. Enter the number of objects to get.

-Index <Int32[]>

  • Default value is None
  • Accepts pipeline input False

Specifies an array of objects based on their index values. Enter the indexes in a comma-separated list.

Indexes in an array begin with 0, where 0 represents the first value and (n-1) represents the last value.

-InputObject <PSObject>

  • Default value is None
  • Accepts pipeline input ByValue

Specifies objects to send to the cmdlet through the pipeline. This parameter enables you to pipe objects to Select-Object .

When you use the InputObject parameter with Select-Object , instead of piping command results to Select-Object , the InputObject value-even if the value is a collection that is the result of a command, such as `-InputObject (Get-Process)`-is treated as a single object. Because InputObject cannot return individual properties from an array or collection of objects, it is recommended that if you use Select-Object to filter a collection of objects for those objects that have specific values in defined properties, you use Select-Object in the pipeline, as shown in the examples in this topic.

-Last <Int32>

  • Default value is None
  • Accepts pipeline input False

Specifies the number of objects to select from the end of an array of input objects.

-Property <Object[]>

  • Default value is None
  • Accepts pipeline input False

Specifies the properties to select. Wildcards are permitted.

The value of the Property parameter can be a new calculated property. To create a calculated, property, use a hash table. Valid keys are:

- Name (or Label) <string>

- Expression <string> or <script block>

-Skip <Int32>

  • Default value is False
  • Accepts pipeline input False

Ignores the specified number of objects and then gets the remaining objects. Enter the number of objects to skip.

-SkipLast <Int32>

  • Default value is None
  • Accepts pipeline input False

@{Text=}

-Unique [<SwitchParameter>]

  • Default value is False
  • Accepts pipeline input False

Specifies that if a subset of the input objects has identical properties and values, only a single member of the subset will be selected.

This parameter is case-sensitive. As a result, strings that differ only in character casing are considered to be unique.

-Wait [<SwitchParameter>]

  • Default value is False
  • Accepts pipeline input False

Indicates that the cmdlet turns off optimization.Windows PowerShell runs commands in the order that they appear in the command pipeline and lets them generate all objects. By default, if you include a Select-Object command with the First or Index parameters in a command pipeline, Windows PowerShell stops the command that generates the objects as soon as the selected number of objects is generated.

This parameter was introduced in Windows PowerShell 3.0.

<CommonParameters>

This cmdlet supports the common parameters: Verbose, Debug,ErrorAction, ErrorVariable, WarningAction, WarningVariable,OutBuffer, PipelineVariable, and OutVariable.

Inputs
System.Management.Automation.PSObject
You can pipe any object to Select-Object .
Outputs
System.Management.Automation.PSObject
Examples
  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.

  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.

  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.

  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.

  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.

  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.

  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.

  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.

Additional 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 at 
 http://go.microsoft.com/fwlink/?LinkId=223385http://go.microsoft.com/fwlink/?LinkId=223385
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