Table of contents
ISE
TOC
Collapse the table of content
Expand the table of content

Get-Unique

JuanPablo Jofre|Last Updated: 11/17/2016
|
2 Contributors

SYNOPSIS

Returns unique items from a sorted list.

SYNTAX

AsString (Default)

Get-Unique [-InputObject <PSObject>] [-AsString] [<CommonParameters>]

UniqueByType

Get-Unique [-InputObject <PSObject>] [-OnType] [<CommonParameters>]

DESCRIPTION

The Get-Unique cmdlet compares each item in a sorted list to the next item, eliminates duplicates, and returns only one instance of each item. The list must be sorted for the cmdlet to work properly.

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

EXAMPLES

-------------------------- EXAMPLE 1 --------------------------

PS C:\>$a = $(foreach ($line in get-content C:\Test1\File1.txt) {$line.tolower().split(" ")}) | sort | get-unique
PS C:\>$a.count

These commands find the number of unique words in a text file.

The first command gets the content of the File.txt file. It converts each line of text to lowercase letters and then splits each word onto a separate line at the space (" "). Then, it sorts the resulting list alphabetically (the default) and uses the Get-Unique cmdlet to eliminate any duplicate words. The results are stored in the $a variable.

The second command uses the Count property of the collection of strings in $a to determine how many items are in $a.

-------------------------- EXAMPLE 2 --------------------------

PS C:\>1,1,1,1,12,23,4,5,4643,5,3,3,3,3,3,3,3 | sort-object | Get-Unique

This command finds the unique members of the set of integers. The first command takes an array of integers typed at the command line, pipes them to the Sort-Object cmdlet to be sorted, and then pipes them to Get-Unique, which eliminates duplicate entries.

-------------------------- EXAMPLE 3 --------------------------

PS C:\>get-childitem | sort-object {$_.GetType()} |  unique -OnType

This command uses the Get-ChildItem cmdlet to retrieve the contents of the local directory, which includes files and directories. The pipeline operator (|) sends the results to the Sort-Object cmdlet. The "$_.GetType()" statement applies the GetType method to each file or directory. Then, Sort-Object sorts the items by type. Another pipeline operator sends the results to Get-Unique. The OnType parameter directs Get-Unique to return only one object of each type.

-------------------------- EXAMPLE 4 --------------------------

PS C:\>get-process | sort-object | select processname | get-unique -asstring

This command gets the names of processes running on the computer with duplicates eliminated.

The Get-Process command gets all of the processes on the computer. The pipeline operator (|) passes the result to Sort-Object, which, by default, sorts the processes alphabetically by ProcessName. The results are piped to the Select-Object cmdlet, which selects only the values of the ProcessName property of each object. The results are then piped to Get-Unique to eliminate duplicates.

The AsString parameter tells Get-Unique to treat the ProcessName values as strings. Without this parameter, Get-Unique treats the ProcessName values as objects and returns only one instance of the object, that is, the first process name in the list.

PARAMETERS

-AsString

Treats the data as a string. Without this parameter, data is treated as an object, so when you submit a collection of objects of the same type to Get-Unique, such as a collection of files, it returns just one (the first). You can use this parameter to find the unique values of object properties, such as the file names.

Type: SwitchParameter
Parameter Sets: AsString
Aliases: 

Required: False
Position: Named
Default value: False
Accept pipeline input: False
Accept wildcard characters: False

-InputObject

Accepts input for Get-Unique. Enter a variable that contains the objects or type a command or expression that gets the objects.

Get-Unique treats the input submitted by using InputObject as a collection; it does not enumerate individual items in the collection. Because the collection is a single item, input submitted by using InputObject is always returned unchanged.

Type: PSObject
Parameter Sets: (All)
Aliases: 

Required: False
Position: Named
Default value: None
Accept pipeline input: True (ByValue)
Accept wildcard characters: False

-OnType

Returns only one object of each type.

Type: SwitchParameter
Parameter Sets: UniqueByType
Aliases: 

Required: False
Position: Named
Default value: False
Accept pipeline input: False
Accept wildcard characters: False

CommonParameters

This cmdlet supports the common parameters: -Debug, -ErrorAction, -ErrorVariable, -InformationAction, -InformationVariable, -OutVariable, -OutBuffer, -PipelineVariable, -Verbose, -WarningAction, and -WarningVariable. For more information, see about_CommonParameters (http://go.microsoft.com/fwlink/?LinkID=113216).

INPUTS

System.Management.Automation.PSObject

You can pipe any type of object to Get-Unique.

OUTPUTS

System.Management.Automation.PSObject

The type of object that Get-Unique returns is determined by the input.

NOTES

  • You can also refer to Get-Unique by its built-in alias, "gu". For more information, see about_Aliases.

    To sort a list, use Sort-Object. You can also use the Unique parameter of Sort-Object to find the unique items in a list.

*

Select-Object

Sort-Object

© 2016 Microsoft