Clear-Host sometimes leaves a line at the top of the screen

[PrzemyslawKlys]

I am aware of closed issue Clear-Host does not clear the previous content (Powershell) #3126 implemented in Implement a pair of shims for cls, Clear-Host in conpty mode #5627 but it didn't resolve this issue totally.

Environment

Windows build number: 

Platform ServicePack Version      VersionString
-------- ----------- -------      -------------
 Win32NT             10.0.18363.0 Microsoft Windows NT 10.0.18363.0

Windows Terminal version (if applicable): 0.11.1251.0

Steps to reproduce

Open Terminal, type Get-Help, Type Clear-Host, Scroll up

Typing Get-Process, Clear-Host shows a similar issue.

Expected behavior

Clear-Host should always clear screen without any scrollback possible.

Actual behavior

Some stuff is left (1 line at the top).

[DHowett-MSFT]

I can't reproduce this with any version of Windows PowerShell or PowerShell Core. Can you share your settings.json?

[PrzemyslawKlys]

For proof sake

// To view the default settings, hold "alt" while clicking on the "Settings" button.
// For documentation on these settings, see: https://aka.ms/terminal-documentation
{
    "$schema": "https://aka.ms/terminal-profiles-schema",
    "defaultProfile": "{61c54bbd-c2c6-5271-96e7-009a87ff44bf}",
    "profiles": [
        {
            // Make changes here to the powershell.exe profile
            "guid": "{61c54bbd-c2c6-5271-96e7-009a87ff44bf}",
            "name": "Windows PowerShell",
            "commandline": "powershell.exe",
            "hidden": false
        },
        {
            // Make changes here to the cmd.exe profile
            "guid": "{0caa0dad-35be-5f56-a8ff-afceeeaa6101}",
            "name": "cmd",
            "commandline": "cmd.exe",
            "hidden": false
        },
        {
            "guid": "{574e775e-4f2a-5b96-ac1e-a2962a402336}",
            "hidden": false,
            "name": "PowerShell 7",
            "source": "Windows.Terminal.PowershellCore"
        },
        {
            "guid": "{b453ae62-4e3d-5e58-b989-0a998ec441b8}",
            "hidden": false,
            "name": "Azure Cloud Shell",
            "source": "Windows.Terminal.Azure"
        },
        {
            "guid": "{a3a2e83a-884a-5379-baa8-16f193a13b21}",
            "hidden": false,
            "name": "PowerShell 7 Preview",
            "source": "Windows.Terminal.PowershellCore"
        }
    ],
    // Add custom color schemes to this array
    "schemes": [],
    // Add any keybinding overrides to this array.
    // To unbind a default keybinding, set the command to "unbound"
    "keybindings": []
}

[PrzemyslawKlys]

Actually this only happens in Windows Powershell. PowerShell 7 is good for me.

[DHowett-MSFT]

Okay this is really strange. Does it reproduce if you make the Windows PowerShell window one line taller, and then one line shorter, before you try it? I wonder if it disagrees about how tall the screen is ...

[PrzemyslawKlys]

It doesn't matter. Tried to make it very small or very large. Always 1 line above prompt is there.

[zadjii-msft]

Hey so we saw something kinda similar over in #5753.

Can you share the output of

gc function:/Prompt

?

Do you have any customizations you've made to your powershell prompt in your profile.ps1?

[PrzemyslawKlys]

code $profile

Clear-Host
Write-Color "Windows PowerShell"
Write-Color "Copyright (C) Microsoft Corporation. All rights reserved." -LinesAfter 1

#Write-Host "Windows PowerShell"
#Write-Host "Copyright (C) Microsoft Corporation. All rights reserved."
#Write-Host
# Chocolatey profile
$ChocolateyProfile = "$env:ChocolateyInstall\helpers\chocolateyProfile.psm1"
if (Test-Path($ChocolateyProfile)) {
  Import-Module "$ChocolateyProfile"
}

[PrzemyslawKlys]

It may be useful -> %SystemRoot%\system32\WindowsPowerShell\v1.0\powershell.exe -nologo is how Windows PowerShell is started (not terminal one). But maybe you use same shortcut to start it? C:\Users\przemyslaw.klys\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Windows PowerShell

[jrd-lewis]

Even on a clean install of both PowerShell 7 and Windows Terminal, I can't clear the history on PowerShell or PowerShell 7. It's still there if you scroll up. (See my unresolved, but strangely closed #4461) Even the command for cmd to clear PS's history isn't respected in Windows Terminal.

[zadjii-msft]

See my unresolved, but strangely closed #4461

That issue was closed because it was a duplicate of another issue, issue #3126, which was fixed in #5627, which was released in v0.11.1251.0. @jrd-lewis are you still seeing this in v0.11.1251.0?

[PrzemyslawKlys]

@cawoodm regarding VSCode you need to update PowerShell and then check settings

It was fixed long time ago :-)

[DHowett-MSFT]

Also, when the changes made to the pseudoconsole for Clear-Host get integrated into a Windows build, VSCode will see the same benefits 😄

[PrzemyslawKlys]

Well you just need to fix my PS 5.1 terminal and you're good to go :-p

[DHowett-MSFT]

1. If we had any idea why that was happening, we would definitely have tried to fix it already ;)

2. Meh, PowerShell 7 is where it's at now!

---

Would you mind sharing a "debugging transcript"? Careful - this will capture all your input.

First, open settings.json, and add the following at the top level.

"debugFeatures": true

Then hold down Left Alt and Right Alt when opening a new Windows PowerShell tab.

It'll look like this when it's working:

Reproduce the issue.

Capture the transcript from the split pane. If there's any sensitive input or output, feel free to reach out to me through the e-mail address on my GitHub profile.

[PrzemyslawKlys]

␛[2J␛[m␛[HWindows␣PowerShell␍␊Copyright␣(C)␣Microsoft␣Corporation.␣All␣rights␣reserved.␛[4;1HTry␣the␣new␣cross-platform␣PowerShell␣https://aka.ms/pscore6␛]0;Windows␣PowerShell␇␛[?25h␛[?25l␛[6;1H␛[?25h␛[?25l␛[H␛[?25h␛[?25l␛[3J␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␛[H␛[?25h␛[97mWindows␣PowerShell␛[?25l␛[m␛[97m␍␊Copyright␣(C)␣Microsoft␣Corporation.␣All␣rights␣reserved.␛[4;1H␛[?25h␛[mPS␣C:\Users\przemyslaw.klys>␣g␛[?25l␛[93mg␛[?25he␛[m␛[?25l␛[93m␈ge␛[?25ht␛[m␛[?25l␛[93m␛[4;30Hget␛[?25h-␛[m␛[?25l␛[93m␛[4;30Hget-␛[?25hh␛[m␛[?25l␛[93m␛[4;30Hget-h␛[?25he␛[m␛[?25l␛[93m␛[4;30Hget-he␛[?25hl␛[m␛[?25l␛[93m␛[4;30Hget-hel␛[?25hp␛[m␛[?25l␛[93m␛[4;30Hget-help␛[?25h␍␛[m␍␊␛[?25l␍␊TOPIC␍␊␣␣␣␣Windows␣PowerShell␣Help␣System␛[9;1HSHORT␣DESCRIPTION␍␊␣␣␣␣Displays␣help␣about␣Windows␣PowerShell␣cmdlets␣and␣concepts.␣␛[12;1HLONG␣DESCRIPTION␍␊␣␣␣␣Windows␣PowerShell␣Help␣describes␣Windows␣PowerShell␣cmdlets,␍␊␣␣␣␣functions,␣scripts,␣and␣modules,␣and␣explains␣concepts,␣including␍␊␣␣␣␣the␣elements␣of␣the␣Windows␣PowerShell␣language.␛[17;1H␣␣␣␣Windows␣PowerShell␣does␣not␣include␣help␣files,␣but␣you␣can␣read␣the␍␊␣␣␣␣help␣topics␣online,␣or␣use␣the␣Update-Help␣cmdlet␣to␣download␣help␣files␍␊␣␣␣␣to␣your␣computer␣and␣then␣use␣the␣Get-Help␣cmdlet␣to␣display␣the␣help␍␊␣␣␣␣topics␣at␣the␣command␣line.␛[22;1H␣␣␣␣You␣can␣also␣use␣the␣Update-Help␣cmdlet␣to␣download␣updated␣help␣files␍␊␣␣␣␣as␣they␣are␣released␣so␣that␣your␣local␣help␣content␣is␣never␣obsolete.␣␛[25;1H␣␣␣␣Without␣help␣files,␣Get-Help␣displays␣auto-generated␣help␣for␣cmdlets,␣␍␊␣␣␣␣functions,␣and␣scripts.␛[29;1H␣␣ONLINE␣HELP␣␣␣␣␍␊␣␣␣␣You␣can␣find␣help␣for␣Windows␣PowerShell␣online␣in␣the␣TechNet␣Library␍␊␣␣␣␣beginning␣at␣http://go.microsoft.com/fwlink/?LinkID=108518.␣␛[33;1H␣␣␣␣To␣open␣online␣help␣for␣any␣cmdlet␣or␣function,␣type:␛[35;1H␣␣␣␣␣␣␣␣Get-Help␣<cmdlet-name>␣-Online␣␣␣␣␛[37;1H␣␣UPDATE-HELP␍␊␣␣␣␣To␣download␣and␣install␣help␣files␣on␣your␣computer:␛[40;1H␣␣␣␣␣␣␣1.␣Start␣Windows␣PowerShell␣with␣the␣"Run␣as␣administrator"␣option.␍␊␣␣␣␣␣␣␣2.␣Type:␛[43;1H␣␣␣␣␣␣␣␣␣␣Update-Help␍␛[?25h␊␊␣␣␣␣After␣the␣help␣files␣are␣installed,␣you␣can␣use␣the␣Get-Help␣cmdlet␣to␍␊␣␣␣␣display␣the␣help␣topics.␣You␣can␣also␣use␣the␣Update-Help␣cmdlet␣to␍␊␣␣␣␣download␣updated␣help␣files␣so␣that␣your␣local␣help␣files␣are␣always␍␊␣␣␣␣up-to-date.␍␊␊␣␣␣␣For␣more␣information␣about␣the␣Update-Help␣cmdlet,␣type:␍␊␊␣␣␣␣␣␣␣Get-Help␣Update-Help␣-Online␍␊␊␣␣␣␣or␣go␣to:␣http://go.microsoft.com/fwlink/?LinkID=210614␍␊␊␊␣␣GET-HELP␍␊␣␣␣␣The␣Get-Help␣cmdlet␣displays␣help␣at␣the␣command␣line␣from␣content␣in␍␊␣␣␣␣help␣files␣on␣your␣computer.␣Without␣help␣files,␣Get-Help␣displays␣basic␍␊␣␣␣␣help␣about␣cmdlets␣and␣functions.␣You␣can␣also␣use␣Get-Help␣to␣display␍␊␣␣␣␣online␣help␣for␣cmdlets␣and␣functions.␍␊␊␣␣␣␣To␣get␣help␣for␣a␣cmdlet,␣type:␍␊␊␣␣␣␣␣␣␣␣Get-Help␣<cmdlet-name>␍␊␊␣␣␣␣To␣get␣online␣help,␣type:␍␊␊␣␣␣␣␣␣␣␣Get-Help␣<cmdlet-name>␣-Online␍␊␊␣␣␣␣The␣titles␣of␣conceptual␣topics␣begin␣with␣"About_".␍␊␣␣␣␣To␣get␣help␣for␣a␣concept␣or␣language␣element,␣type:␍␊␊␣␣␣␣␣␣␣␣Get-Help␣About_<topic-name>␍␊␊␣␣␣␣To␣search␣for␣a␣word␣or␣phrase␣in␣all␣help␣files,␣type:␍␊␊␣␣␣␣␣␣␣␣Get-Help␣<search-term>␍␊␊␣␣␣␣For␣more␣information␣about␣the␣Get-Help␣cmdlet,␣type:␍␊␊␣␣␣␣␣␣␣␣Get-Help␣Get-Help␣-Online␍␊␊␣␣␣␣or␣go␣to:␣http://go.microsoft.com/fwlink/?LinkID=113316␍␊␊␊␣␣EXAMPLES:␍␊␣␣␣␣␣␣Save-Help␣␣␣␣␣␣␣␣␣␣␣␣␣␣:␣Download␣help␣files␣from␣the␣Internet␣and␣saves␍␊␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣them␣on␣a␣file␣share.␍␊␣␣␣␣␣␣Update-Help␣␣␣␣␣␣␣␣␣␣␣␣:␣Downloads␣and␣installs␣help␣files␣from␣the␍␊␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣Internet␣or␣a␣file␣share.␍␊␣␣␣␣␣␣Get-Help␣Get-Process␣␣␣:␣Displays␣help␣about␣the␣Get-Process␣cmdlet.␍␊␣␣␣␣␣␣Get-Help␣Get-Process␣-Online␍␊␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣:␣Opens␣online␣help␣for␣the␣Get-Process␣cmdlet.␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␛[43;119H␍␊␊␣␣␣␣␣␣Help␣Get-Process␣␣␣␣␣␣␣:␣Displays␣help␣about␣Get-Process␣one␣page␣at␣a␣time.␍␊␣␣␣␣␣␣Get-Process␣-?␣␣␣␣␣␣␣␣␣:␣Displays␣help␣about␣the␣Get-Process␣cmdlet.␍␊␣␣␣␣␣␣Get-Help␣About_Modules␣:␣Displays␣help␣about␣Windows␣PowerShell␣modules.␍␊␣␣␣␣␣␣Get-Help␣remoting␣␣␣␣␣␣:␣Searches␣the␣help␣topics␣for␣the␣word␣"remoting."␍␊␊␣␣SEE␣ALSO:␍␊␣␣␣␣␣␣about_Updatable_Help␍␊␣␣␣␣␣␣Get-Help␍␊␣␣␣␣␣␣Save-Help␍␊␣␣␣␣␣␣Update-Help␍␊␊␊␊␊␊␊␊␊␊␊␊␊␊PS␣C:\Users\przemyslaw.klys>␛[1Cc␛[?25l␛[93mc␛[?25hl␛[m␛[?25l␛[93m␈cl␛[?25he␛[m␛[?25l␛[93m␛[43;30Hcle␛[?25ha␛[m␛[?25l␛[93m␛[43;30Hclea␛[?25hr␛[m␛[?25l␛[93m␛[43;30Hclear␛[?25h␍␛[m␛[?25l␛[3J␍␊␛[HPS␣C:\Users\przemyslaw.klys>␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␍␊␛[K␛[1;30H␛[?25h

[harikanth64]

Same issue for me. It doesn't look like a terminal issue. It also causes in windows powershell.
I am using pwsh 7.1 version. Works fine in v5.1 PowerShell

[j4james]

I've just been looking at this issue, and while I can't reproduce the problem if I do Clear-Host by itself, it does happen quite consistently if I do something like echo Hello; Clear-Host. I can also reproduce it consistently in a cmd shell with just cls (recently reported in #13320). I think there is an element of timing involved here, which may explain why some people are seeing it more than others.

But what appears to be happening is there's a linefeed that triggers an InvalidateScroll in the XtermEngine which sets the _scrollDelta. But before the conpty renderer has flushed that, we get a ScrollConsoleScreenBuffer or FillConsoleOutputCharacter call from which we detect the Clear-Host/cls. That triggers the ED3 which clears the scrollback, but we've still got the pending _scrollDelta to deal with. So when the conpty renderer eventually repaints, we end up pushing an unwanted line into the previously cleared scrollback.

One simple way to fix this is to reset the _scrollDelta in the ManuallyClearScrollback method. That feels a bit flaky though, and I think the more correct solution is to call TriggerFlush on the renderer before calling ManuallyClearScrollback. That's likely to generate more throughput, but I think there's less risk that way of something else leaking through after the ED3.

[ghost]

🎉This issue was addressed in #13324, which has now been successfully released as Windows Terminal v1.14.186.:tada:

Handy links:

• Release Notes
• Store Download

[ghost]

🎉This issue was addressed in #13324, which has now been successfully released as Windows Terminal Preview v1.15.186.:tada:

Handy links:

• Release Notes
• Store Download