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This is the built-in help made by Microsoft for the command 'Unblock-File', in PowerShell version 5 - as retrieved from Windows version 'Microsoft Windows Server 2012 R2 Standard' PowerShell help files on 2016-06-23.

For PowerShell version 3 and up, where you have Update-Help, this command was run just before creating the web pages from the help files.


Unblocks files that were downloaded from the Internet.


Unblock-File [-Path] <String[]> [-InformationAction {SilentlyContinue | Stop | Continue | Inquire | Ignore | Suspend}] [-InformationVariable [<System.String>]] [-Confirm]
[-WhatIf] [<CommonParameters>]
Unblock-File [-InformationAction {SilentlyContinue | Stop | Continue | Inquire | Ignore | Suspend}] [-InformationVariable [<System.String>]] -LiteralPath <String[]>
[-Confirm] [-WhatIf] [<CommonParameters>]

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The Unblock-File cmdlet lets you open files that were downloaded from the Internet. It unblocks Windows PowerShell script files that were downloaded from the Internet so you
can run them, even when the Windows PowerShell execution policy is RemoteSigned. By default, these files are blocked to protect the computer from untrusted files.

Before using the Unblock-File cmdlet, review the file and its source and verify that it is safe to open.

Internally, the Unblock-File cmdlet removes the Zone.Identifier alternate data stream, which has a value of "3" to indicate that it was downloaded from the Internet.

For more information about Windows PowerShell execution policies, see about_Execution_Policies (http://go.microsoft.com/fwlink/?LinkID=135170).

This cmdlet is introduced in Windows PowerShell 3.0.



Online Version: http://go.microsoft.com/fwlink/p/?linkid=294021
FileSystem Provider




Example 1: Unblock a file

PS C:\>Unblock-File -Path C:\Users\User01\Documents\Downloads\PowerShellTips.chm

This command unblocks the PowerShellTips.chm file.

Example 2: Unblock multiple files

PS C:\>dir C:\Downloads\*PowerShell* | Unblock-File

This command unblocks all of the files in the C:\Downloads directory whose names include "PowerShell". Do not run a command like this one until you have verified that all
files are safe.

Example 3: Find and unblock scripts

The first command uses the Stream parameter of the Get-Item cmdlet get files with the Zone.Identifier stream.Although you could pipe the output directly to the Unblock-File
cmdlet (Get-Item * -Stream "Zone.Identifier" -ErrorAction SilentlyContinue | ForEach {Unblock-File $_.FileName}), it is prudent to review the file and confirm that it is
safe before unblocking.
PS C:\>Get-Item * -Stream "Zone.Identifier" -ErrorAction SilentlyContinue
FileName: C:\ps-test\Start-ActivityTracker.ps1

Stream Length
------ ------
Zone.Identifier 26

The second command shows what happens when you run a blocked script in a Windows PowerShell session in which the execution policy is RemoteSigned. The RemoteSigned policy
prevents you from running scripts that are downloaded from the Internet unless they are digitally signed.
PS C:\>C:\ps-test\Start-ActivityTracker.ps1
c:\ps-test\Start-ActivityTracker.ps1 : File c:\ps-test\Start-ActivityTracker.ps1 cannot
be loaded. The file c:\ps-test\Start-ActivityTracker.ps1 is not digitally signed. The script
will not execute on the system. For more information, see about_Execution_Policies at
At line:1 char:1
+ c:\ps-test\Start-ActivityTracker.ps1
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : SecurityError: (:) [], PSSecurityException
+ FullyQualifiedErrorId : UnauthorizedAccess

The third command uses the Unblock-File cmdlet to unblock the script so it can run in the session.
PS C:\>Get-Item C:\ps-test\Start-ActivityTracker.ps1 | Unblock-File

This command shows how to find and unblock Windows PowerShell scripts.