Windows PowerShell Select-Object

Examples of Windows PowerShell Select-Object

PowerShell’s Select-Object is ideal for filtering properties before you output them to file, printer or even read them on-screen.  Perhaps the underlying command produces too much information, with Select-Object you can reduce the number of columns passed to the next element, Format-Table or Out-File.

Topics for PowerShell Select-Object

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Introduction to PowerShell Select-Object

Example: Choose Properties Returned by Get-Process

Let us assume that you want to list the computer’s running processes sorted by CPU usage.  The point of piping the output of the ‘Sort’ phrase into Select-Object is that you get to choose which properties are displayed.  Incidentally, selecting the properties also means that you get to choose the order, in this case, I like the name of the process in the first column.

# PowerShell Select-Object Example
Clear-Host
Get-Process | Sort-Object cpu -descending | `
Select-Object Name, cpu, handles, workingset

Note 1:  You can shorten Select-Object to plain ‘Select’, this is because PowerShell has an alias of that name.

Note 2:  For this particular job I prefer to use Format-Table because I can achieve the same result and in addition employ -auto to tighten up the columns.

# PowerShell comparing Select-Object with Format-Table
Clear-Host
Get-Process | Sort-Object cpu -descending | `
Format-Table Name, cpu, handles, workingset -auto

Conclusion: What can Select-Object do that Format-Table cannot?  Let investigate the parameters with Get-Help.

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Researching Select-Object’s Parameters

To see the full list of parameters call for Get-Help

# PowerShell Select-Object Parameters
Clear-Host
Get-Help Select-Object -full

Result: Help reveals that Select-Object has parameters which are not be available if you used Format-Table, for example, -first, -last -expand, -skip and -unique.

# PowerShell Select-Object Parameters
Clear-Host
Get-Process | Sort-Object cpu -descending | `
Select-Object name, cpu, handles, workingset -first 10

Comparing the Speed of Select-Object with Format-Table

Let us try an experiment; we will measure the time it takes to complete the same task but with one difference, filtering with Select-Object or FT (Format-Table).

Experiment A: Format-Table Speed Test

# PowerShell comparing the speed of Format-Table with Select
Clear-Host
Measure-Command {
Get-Process | Sort-Object WorkingSet -descending | `
Format-Table Name, cpu, handles, workingset -auto
}

Result: 75 TotalMilliseconds (fastest of 3 to compensate for caching)

Experiment B: Select-Object Speed Test

# PowerShell Select-Object Speed Test
Clear-Host
Measure-Command{
Get-Process | Sort-Object WorkingSet -descending | `
Select-Object Name, cpu, handles, workingset
}

Result: 28 TotalMilliseconds (fastest of 3 to compensate for caching)

Conclusion: Select-Object is much faster than Format-Table, consequently I only use Format-Table when I need the -Auto feature.

See more on PowerShell’s Measure-Object cmdlet ยป

 

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Other Uses of Select in PowerShell Cmdlet

There are two other ways that PowerShell uses ‘Select’.

Perhaps the most common way is to employ Select in a WMI Query Language (WQL) statement.  Such Get-WmiObject examples which use ‘-query’ to introduce a classic ‘Select *’ phrase.

The second context for ‘Select’ in PowerShell is Select-String.  This cmdlet not only opens a file, but also checks for a word, a phrase, or in fact any pattern match. 

More PowerShell Object Cmdlets

You can use Get-Command to research more of PowerShell's 'Object' family.  All you need to do is append the -Noun parameter.  Incidentally, you could also try -Verb Select.

Clear-Host
Get-Command -Noun Object

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See more PowerShell examples for syntax

PowerShell Home  • Syntax  • ISE (GUI)  • Pipeline  • Format-Table  • Select-Object

Compare-Object  • Compare-Object (Registry)  • Group-Object  • Sort-Object  • Foreach

Please email me if you have a better example script. Also please report any factual mistakes, grammatical errors or broken links, I will be happy to correct the fault.