Powershell - How to get all the text output from current session as a string?

I have a long script that runs many commands. These commands print text to the screen via standard output and standard error. I want to add some logic at the end of the script that takes all text printed to the screen (standard out or standard error) and saves it to a text file.

However, I do not want to redirect standard output and standard error to a text file because I want the user of the script to be able to see all the text getting printed to the screen in real time as the script runs. Indeed, at some points in the script, some of the commands may ask for user input. Instead, I want to be able to "GetScreenContentsText()" and then write the output of this to the screen.

Is there a way to do this in PowerShell?

As Mathias points out in a comment, the Start-Transcript cmdlet (followed by a matching Stop-Transcript call) is generally the right tool for creating session transcripts.

However, Start-Transcript doesn't capture everything and has general problems and limitations (current as of PowerShell (Core) 7 v7.5.x):

• Interactive prompts (Read-Host, [Console]::ReadLine()) are not transcribed - you'll see neither the prompt string nor what the user typed.

• Even output can situationally be missing from the transcript, as discussed in GitHub issue #10994; notably output from some console applications, such as robocopy.exe.

• Error messages can be transcribed twice and using transcription can change the script's behavior - see GitHub issue #4645.

• VT sequences (ANSI escape codes) are not captured, so any coloring shown in the console is lost - see GitHub issue #11567.

  • They are captured - invariably - in Windows PowerShell (the legacy, ships-with-Windows, Windows-only edition of PowerShell whose latest and last version is 5.1), though coloring achieved via the legacy console WinAPI functions used by commands such as Write-Host -Foregroundcolor ...) is not.

The first of the linked GitHub issues prompted the following response from the PowerShell committee, which reflects the status quo as of PowerShell 7.5.x (emphasis added):

@PowerShell/powershell-committee reviewed this, we believe a complete solution for transcription (like the unix script command) [is called for;] would love to see the community build a new cmdlet (published to PSGallery) that uses ptty or on Windows grabbing the screen buffer, but the ask is out of scope for the current transcription framework.

Speaking of the script utility on Unix-like platforms:

• While it is a superior alternative to Start-Transcript in general there (though not designed to be used from inside scripts), PowerShell's PSReadLine module, which is also used for prompting users via Read-Host, doesn't play nice with it.

As for possible workarounds:

• Try to find a third-party solution that doesn't have the limitations of Start-Transcript

  • The PowerShellLogging module promises a solution, but as of this writing it apparently only works in Windows PowerShell, no longer in PowerShell (Core) 7.
  • While a fix has apparently been made in the source code, an update was never published (see GitHub issue #9), but building the module yourself from the source code may work.

• Otherwise, unfortunately, it sounds like you'll have to manually duplicate prompt strings and user input in your script's output in order for them to be captured in the transcript - if modifying the script is an option.