Unblock-File [-Confirm] -LiteralPath* <String[]> [-WhatIf] [<CommonParameters>]
Unblock-File [-Path*] <String[]> [-Confirm] [-WhatIf] [<CommonParameters>]
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 was introduced in Windows PowerShell 3.0.
-Confirm [<SwitchParameter>]
Prompts you for confirmation before running the cmdlet.
-LiteralPath <String[]>
Specifies the files to unblock. Unlike Path , the value of the LiteralPath parameter is used exactly as it is typed. No characters are interpreted as wildcards. If the path includes escape characters, enclose it in single quotation marks. Single quotation marks tell Windows PowerShell not to interpret any characters as escape sequences.
-Path <String[]>
Specifies the files to unblock. Wildcard characters are supported.
-WhatIf [<SwitchParameter>]
Shows what would happen if the cmdlet runs. The cmdlet is not run.
<CommonParameters>
This cmdlet supports the common parameters: Verbose, Debug,ErrorAction, ErrorVariable, WarningAction, WarningVariable,OutBuffer, PipelineVariable, and OutVariable.
PS C:\> Unblock-File -Path C:\Users\User01\Documents\Downloads\PowerShellTips.chm
This command unblocks the PowerShellTips.chm file.
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.
PS C:\> Get-Item * -Stream "Zone.Identifier" -ErrorAction SilentlyContinue
FileName: C:\ps-test\Start-ActivityTracker.ps1
Stream Length
------ ------
Zone.Identifier 26
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:\> 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
http://go.microsoft.com/fwlink/?LinkID=135170.
At line:1 char:1
+ c:\ps-test\Start-ActivityTracker.ps1
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : SecurityError: (:) [], PSSecurityException
+ FullyQualifiedErrorId : UnauthorizedAccess
The RemoteSigned policy prevents you from running scripts that are downloaded from the Internet unless they are digitally signed.
PS C:\> Get-Item C:\ps-test\Start-ActivityTracker.ps1 | Unblock-File
This command shows how to find and unblock Windows PowerShell scripts.
The Unblock-File * cmdlet works only in file system drives. Unblock-File performs the same operation as the Unblock button on the Properties * dialog box in File Explorer. If you use the Unblock-File * cmdlet on a file that is not blocked, the command has no effect on the unblocked file and the cmdlet does not generate errors.
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