Delete/clear opened text file which is used by another process

Question

I'm getting following exception:

The process cannot access the file because it is being used by another process

I want to simply clear a log file that is opened via PowerShell. Like following:

$path = ...
Clear-Content $path -Force

How can I do this even if the file is opened? Windows Editor and Notepad++ can do it while the file is opened by my log viewer, but I can't do it in PowerShell. How do the editors do this? Can I somehow achieve this with PowerShell as well?

I also tried Set-Content to clear the content of the file with the same result.

EDIT - Setup

• my program writes to the log file (without problems, always, even if the log viewer is opened)
• I use glogg as log viewer (http://glogg.bonnefon.org/)
• If glogg is opened, the Powershell script fails
• I can reliably reproduce this and can see, that Notepad++ and the Windows Editor can overwrite the files content easily and always (as well as my app is still able to write to the log file of course), and glogg immediately displays the new log file content

EDIT 2: ProcMon data

Case 1 - Glogg is opened and powershell fails

11:11:12,1441593    powershell.exe  10304   QueryOpen   D:\VW_LOG.txt   SUCCESS CreationTime: 16.10.2014 09:59:18, LastAccessTime: 16.10.2014 10:13:51, LastWriteTime: 13.10.2017 10:22:07, ChangeTime: 13.10.2017 10:22:07, AllocationSize: 28.672, EndOfFile: 26.451, FileAttributes: A
11:11:12,1442828    powershell.exe  10304   CreateFile  D:\VW_LOG.txt   SHARING VIOLATION   Desired Access: Generic Write, Read Attributes, Disposition: Open, Options: Synchronous IO Non-Alert, Non-Directory File, Open No Recall, Attributes: n/a, ShareMode: Write, AllocationSize: n/a

Case 2 - Glogg is closed and powershell succeeds

11:12:48,9053637    powershell.exe  10304   QueryOpen   D:\VW_LOG.txt   SUCCESS CreationTime: 16.10.2014 09:59:18, LastAccessTime: 16.10.2014 10:13:51, LastWriteTime: 13.10.2017 10:22:07, ChangeTime: 13.10.2017 10:22:07, AllocationSize: 28.672, EndOfFile: 26.451, FileAttributes: A
11:12:48,9055053    powershell.exe  10304   CreateFile  D:\VW_LOG.txt   SUCCESS Desired Access: Generic Write, Read Attributes, Disposition: Open, Options: Synchronous IO Non-Alert, Non-Directory File, Open No Recall, Attributes: n/a, ShareMode: Write, AllocationSize: n/a, OpenResult: Opened
11:12:48,9055581    powershell.exe  10304   QuerySecurityFile   D:\VW_LOG.txt   SUCCESS Information: Attribute
11:12:48,9055808    powershell.exe  10304   SetAllocationInformationFile    D:\VW_LOG.txt   SUCCESS AllocationSize: 0
11:12:48,9058881    powershell.exe  10304   CloseFile   D:\VW_LOG.txt   SUCCESS 

EDIT 3 - working alternative solution

I call following in my powershell script and it works flawless:

ExecuteSimpleBatch "clear_file.bat" $path

function ExecuteSimpleBatch($file, $par)
{
    $fileName = Split-Path $file -leaf
    $fileFolder = Split-Path $file -parent

    Start-Process "cmd" -ArgumentList '/c', $file, $par -WorkingDirectory $fileFolder -WindowStyle hidden
}

Content of "clear_file.bat":

break > %1

Answer 1

Finally I found a working solution:

Instead of

Clear-Content $path

it's possible to use

"" | Out-File $path -NoNewline -Encoding ASCII

Why

Seems like Clear-Content is creating a new file and replaces the old one with it, while Out-File tries to write into an existing file (so opened read handles do not effect this)