Can you redirect Tee-Object to standard out?

by

To complement zett42’s helpful answer:

If you’re running PowerShell (Core) 7+, you can pass the file path that represents the terminal (console) to the (positionally implied) -FilePath parameter (in Windows PowerShell, this causes an error, unfortunately – see bottom section):

# PowerShell 7+ only

# Windows
Get-Content data.txt | Tee-Object \\.\CON | data_processor.exe

# Unix-like platforms (Linux, macOS)
Get-Content data.txt | Tee-Object /dev/tty | data_processor.exe

# Platform-agnostic
Get-Content data.txt | Tee-Object ($IsWindows ? '\\.\CON': '/dev/tty') | data_processor.exe

This passes all data through while also printing it to the terminal (console), richly formatted, as usual, as it becomes available – unlike with the Tee-Object -Variable approach, which requires collecting all output in memory first (which is a concern both in terms of output timing and memory consumption).

Windows PowerShell solution: Custom proxy (wrapper) function Tee-Host wraps Out-Host while also passing its input through; use it instead of Tee-Object:

function Tee-Host {  
  [CmdletBinding()]
  param(
    [Parameter(ValueFromPipeline)] $InputObject
  )

  begin
  {
    $scriptCmd = { Out-Host }
    $steppablePipeline = $scriptCmd.GetSteppablePipeline($myInvocation.CommandOrigin)
    $steppablePipeline.Begin($PSCmdlet)
  }
  
  process
  {
    # Pass to Out-Host, and therefore to the host (terminal)
    $steppablePipeline.Process($InputObject)
    # Pass through (to the success stream)
    $InputObject 
  }
  
  end
  {
    $steppablePipeline.End()
  }
    
}

  • In effect, Tee-Host behaves like Tee-Object \\.\CON / Tee-Object /dev/tty in PowerShell 7+, where Tee-Host works too.

  • Even in PowerShell 7+ Tee-Host may be preferable, because it uses colored output unconditionally, whereas the coloring behavior of Tee-Object \\.\CON / Tee-Object /dev/tty depends on the value of $PSStyle.OutputRendering

It is the use of a proxy function with a steppable pipeline wrapping Out-Host that ensures that the to-host formatted output looks the same as when the input is directly sent to the host.

More Related Contents:

  1. Displaying Unicode in Powershell
  2. Colored text output in PowerShell console using ANSI / VT100 codes
  3. Get-Aduser -Filter will not accept a variable
  4. In what scenario was Invoke-Expression designed to be used?
  5. Powershell executable isn’t outputting to STDOUT
  6. How can I write/create a powershell script verbatim, from another powershell script?
  7. How to escape special characters in PowerShell?
  8. Read file line by line in PowerShell
  9. How do I pass variables with the Invoke-Command cmdlet?
  10. Access PSObject property indirectly with variable
  11. How to remove all quotations mark in the csv file using powershell script?
  12. Is there a way to set a variable up to place output to stdout or null?
  13. VSCode Change Default Terminal
  14. Set-Content appends a newline (line break, CRLF) at the end of my file
  15. Progress during large file copy (Copy-Item & Write-Progress?)
  16. How do I execute a PowerShell script automatically using Windows task scheduler?
  17. How to export data to CSV in PowerShell?
  18. Waiting for user input with a timeout
  19. Echo equivalent in PowerShell for script testing
  20. Why is an empty PowerShell pipeline not the same as null?
  21. PowerShell script to check the status of a URL
  22. Accessing Windows Credential Manager from PowerShell
  23. Out-FINcodedCommand.ps1 is not recognized – executing a script in the current directory
  24. ConvertTo-JSON an array with a single item
  25. Copy file with square brackets [ ] in the filename and use * wildcard
  26. Why is “
  27. Powershell: Set a Scheduled Task to run when user isn’t logged in
  28. Listing processes by CPU usage percentage in powershell
  29. How to effectively use the `-Filter` parameter on Active Directory cmdlets?
  30. Unix newlines to Windows newlines (on Windows)

Leave a Comment