Get-Unique [-AsString] [-InputObject <PSObject>] [<CommonParameters>]
Get-Unique [-InputObject <PSObject>] [-OnType] [<CommonParameters>]
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.
-AsString [<SwitchParameter>]
Indicates that this cmdlet uses 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.
-InputObject <PSObject>
Specifies input for Get-Unique . Enter a variable that contains the objects or type a command or expression that gets the objects.
This cmdlet 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.
-OnType [<SwitchParameter>]
Indicates that this cmdlet returns only one object of each type.
<CommonParameters>
This cmdlet supports the common parameters: Verbose, Debug,ErrorAction, ErrorVariable, WarningAction, WarningVariable,OutBuffer, PipelineVariable, and OutVariable.
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 $A.
PS C:\> 1,1,1,1,12,23,4,5,4643,5,3,3,3,3,3,3,3 | Sort-Object | Get-Unique
This command finds the unique members of the set of integers. The first command takes an array of integers typed at the command line, pipes them to the Sort-Object cmdlet to be sorted, and then pipes them to Get-Unique , which eliminates duplicate entries.
PS C:\> Get-ChildItem | Sort-Object {$_.GetType()} | Get-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.
PS C:\> Get-Process | Sort-Object | Select-Object 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.
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. *
This work is licensed under a Creative Commons Attribution 4.0 International. It is attributed to Microsoft Corporation and can be found here.
PowerShell Commands