Inconsistent behavior between executing directly from the command line and from inside a KeyHandler.

[LittleNewton]

Prerequisites

• Write a descriptive title.
• Make sure you are able to repro it on the latest released version
• Search the existing issues, especially the pinned issues.

Exception report

The code in question is as follows:

 powershell
Set-PSReadLineKeyHandler -Chord Ctrl+k `
                         -BriefDescription ClearHost `
                         -LongDescription "Clear the console host screen" `
                         -ScriptBlock {
    Clear-Host
}

I intend for the action to clear all command history upon pressing Ctrl+k. However, it should retain the prompt to avoid an unpleasant visual and lack of command indication. When executing Clear-Host directly from the command line, it operates as intended. Yet, when invoking the same through the aforementioned KeyHandler, it wipes the prompt as well, leaving the screen entirely blank.

Screenshot

After pressing Ctrl+k

Using Clear-Host

Environment data

PS Version: 7.3.7
PS HostName: ConsoleHost (Windows Terminal)
PSReadLine Version: 2.3.4
PSReadLine EditMode: Windows
OS: 10.0.19041.3324 (WinBuild.160101.0800)
BufferWidth: 135
BufferHeight: 45

Steps to reproduce

1. Install oh-my-posh using winget.

winget install JanDeDobbeleer.OhMyPosh -s winget

2. Using paradox theme.

How to set the theme? As following,

• $PS code $PROFILE
• Add a new line: oh-my-posh init pwsh --config $env:POSH_THEMES_PATH\paradox.omp.json | Invoke-Expression

3. Add KeyHandler

Set-PSReadLineKeyHandler -Chord Ctrl+k `
                         -BriefDescription ClearHost `
                         -LongDescription "Clear the console host screen" `
                         -ScriptBlock {
    Clear-Host

4. Try Ctrl+k and Clear-Host

Just compare the different behavior.

Expected behavior

I wish Ctrl k keyHandler has the same behavior as type Clear-Host.

Actual behavior

Ctrl k will clear all characters in the terminal.

[LittleNewton]

After pressing Ctrl+k

Using Clear-Host

[daxian-dbw]

This is by design. If you want to have a custom key binding that runs clear-host, then your key binding handler needs to take care of writing out the prompt message. PSReadLine has a default key binding Ctrl+l for clearing screen, you can use that instead of having your own custom binding for it.

PS:1> Get-PSReadLineKeyHandler -Chord "ctrl+l"

Miscellaneous functions
=======================

Key    Function    Description
---    --------    -----------
Ctrl+l ClearScreen Clear the screen and redraw the current line at the top of the screen

[thegraffix]

FWIW, one behavioral difference (that's important to some, but not all) between Clear-Host and the PSReadLineKeyHandler function ClearScreen is that Clear-Host clears the scrollback buffer. The ClearScreen function executes a carriage return everytime it's executed, resulting in a console that looks like this after doing CTRL+L 3x and scrolling up:

It would be cool if the ClearScreen function took into account the OS/environment (e.g. Windows/conhost has always cleared the scrollback buffer, whereas Linux/bash traditionally has not).



But this works just as well:

$args = @{
    BriefDescription = 'ClearHost'
    Chord = 'Ctrl+k'
    Description = 'Clear the console host screen'
    ScriptBlock = {
        [Microsoft.PowerShell.PSConsoleReadLine]::RevertLine()
        [Microsoft.PowerShell.PSConsoleReadLine]::AcceptLine()
        Clear-Host
    }
}
Set-PSReadLineKeyHandler @args