Vscode: "Terminal: Clear" not working as desired

[vivekmalhotra]

Steps to Reproduce:

1. Run a python file using command palette >Python: Run file in terminal window
2. Terminal shows the output. Now, clear the terminal using command palette >Terminal: Clear
3. Terminal gets clear now. Run the file again in the terminal >Python: Run file in terminal window
4. Here is where issue shows up - the terminal still shows all the previous outputs from before the last clear command. IMO, desired should be that terminal should not show any previously cleared outputs.
5. Attached below is a gif of the screen reproducing & visualizing this issue

Does this issue occur when all extensions are disabled?:
Yes, the issue reoccurs. (Note: All except the "Python" extension were disabled. Python extension is needed to run the python file in terminal.

I had also posted in Super User forum thinking this was some issue with my system. And then I tried it on a clean build of VS code and it got repeated. Hence, I decided to post it as a bug.

Link to Super User forum question

VS Code version: Code - Insiders 1.36.0-insider (c089daa858f34631f5f827ff8a0313bf1e2ded6d, 2019-06-07T05:19:15.188Z)
OS version: Windows_NT x64 10.0.18362

System Info

|Item|Value|
|---|---|
|CPUs|Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz (12 x 3696)|
|GPU Status|2d_canvas: enabled
flash_3d: enabled
flash_stage3d: enabled
flash_stage3d_baseline: enabled
gpu_compositing: enabled
multiple_raster_threads: enabled_on
native_gpu_memory_buffers: disabled_software
oop_rasterization: disabled_off
protected_video_decode: enabled
rasterization: enabled
skia_deferred_display_list: disabled_off
skia_renderer: disabled_off
surface_synchronization: enabled_on
video_decode: enabled
viz_display_compositor: disabled_off
webgl: enabled
webgl2: enabled|
|Load (avg)|undefined|
|Memory (System)|15.68GB (7.71GB free)|
|Process Argv||
|Screen Reader|no|
|VM|0%|

Extensions (1)

Extension|Author (truncated)|Version
---|---|---
python|ms-|2019.5.18875

[vscodebot[bot]]

(Experimental duplicate detection)
Thanks for submitting this issue. Please also check if it is already covered by an existing one, like:

• 'Run Python File in Terminal'not working (#74917)
  

[Tyriar]

@vivekmalhotra this is happening because Terminal: Clear tells the frontend (the thing rendering everything) to clear, but the way that the conpty backend works is it will sometimes reprint what it thinks should be visible. Since it doesn't know about our clear it reprints the unwanted output, this doesn't happen on a regular linux/mac backend that conpty is trying to emulate.

@zadjii-msft is there anything that can be done here to tell conpty to not reprint the screen? I suspect python.exe does not enter alt mode so I'm not sure why a reprint is necessary.

[zadjii-msft]

Hmm. That might not be a scenario that works for us right now. We might need to add an extra input sequence/signal to tell conpty to clear the buffer.

I am a little curious why the whole buffer got repainted, that does seem like a bug. However, since conpty does think that all that text is still there (because its buffer wasn't cleared, only the frontend buffer was), it might get more confused by not repainting the entire thing.

[Tyriar]

@zadjii-msft might be better to fix the bug if there is one, rather than add an explicit manually clear the buffer sequence that only works on conpty.

[vscodebot[bot]]

This issue has been closed automatically because it needs more information and has not had recent activity. See also our issue reporting guidelines.

Happy Coding!

[vivekmalhotra]

@zadjii-msft @Tyriar
I can confirm that the issue is still prevalent in the latest insiders build.
Unsure on how to re-open this issue?

[zadjii-msft]

This is a bug that's external to VsCode. It'll be fixed by work on the ConPTY API that'll be tracked by microsoft/terminal#1193.

[vivekmalhotra]

This is a bug that's external to VsCode. It'll be fixed by work on the ConPTY API that'll be tracked by microsoft/terminal#1193.

Thanks for the reply, Mike

[Tyriar]

@vivekmalhotra the bot closed it because of the needs more info label, reopened.

[ghost]

Terminal clear

I run npm in terminal，then end it with "Ctrl + C" , useing code clear and get result as left（I have click enter several times）,useing "ctrl + shift + p" and "terminal clear" get result as right，it clear all and terminal crashed.

terminal will back to line 1 and enterable but not clear character。

用了clear命令后，terminal返回第一行并且可编辑，但是并没有清理界面字符，使用 控制中心的Terminal clear 指令后可以清理，但是terminal崩溃了

[solacens]

So who should be fixing the issue now? VS Code here or Windows Terminal? 😢

Any workaround at the moment? This issue is quite annoying.

[ghost]

No debounce，Push 1s Enter，it still effective，more than 1s

[zadjii-msft]

@solacens

It'll be fixed by work on the ConPTY API that'll be tracked by microsoft/terminal#1193.

[solacens]

@zadjii-msft Thanks for the information. I will keep track on the related issue.

[inliquid]

I've got to exact same problem with my projects after windows update 1803 ->1903 (clean install). No idea what changed, but I've never seen this before.

[mrkarthi]

Hello @Tyriar,

I have assigned the keyboard shortcut 'ALT+M' for clearing the Terminal.

{ "key": "alt+m", "command": "workbench.action.terminal.clear", "when": "terminalFocus" }

Clear the Terminal with the keyboard shortcut.
Type "node index", the cursor jumps in the Terminal.

Press Enter.

Terminal is not cleared.

Please check and let me know your comments.

Best Regards,
Karthi M R.

[kohenkatz]

I have discovered a workaround. It's a little annoying, but it is definitely better than nothing.

You need to clear the terminal with two commands:

• Command Palette Terminal: Clear (or your chosen keyboard shortcut)
• Type cls at the terminal

Interestingly, sometimes just the cls is enough without the Terminal:Clear, and sometimes it isn't. I have not figured out why that would be.

(Note: it used to be that the cls command did not work in the integrated terminal. I guess that there was a fix for that at some point as well.)

[mrkarthi]

@kohenkatz, Thanks for your suggestions.

Command Palette Terminal: Clear (or your chosen keyboard shortcut)

This is not working anyways. I have to manually clear the Terminal by typing cls or clear.

Will this issue be fixed sooner as this is quite troublesome every time?

Best Regards,
Karthi M R.

[escape0707]

It'll be fixed by work on the ConPTY API that'll be tracked by microsoft/terminal#1193.

@mrkarthi I suggest we don't bump this issue anymore, because it's already marked as an upstream problem.

But anyway, feel free to add your thumbs up to this and the upstream issue to add priority to them.

[mhaaz]

@solacens

So who should be fixing the issue now? VS Code here or Windows Terminal? 😢

Any workaround at the moment? This issue is quite annoying.

As previously suggested, you can try entering the builtin command cls (if using cmd-shell) or clear (if using bash or similar). While less quick and annoying, it works reliably for me.

[Yegorich555]

cls command doesn't fix this issue at all for me!

[kohenkatz]

@Yegorich555 As I noted above, you need to use both cls and Terminal: Clear together at the moment. Either one without the other isn't enough.

[vivekmalhotra]

While this issue persists, I want to share what I have been using as a temporary workaround:

1. As of VS-Code v 1.44.0, executing either "cls" or "clear terminal" command in the integrated terminal seems to clear the terminal output properly
2. Although, "Terminal: Clear" still does NOT work properly
3. I have created a keybinding (in my case CTRL+k) to accomplish this.
   Add the following code in your "keybindings.json" file (refer to the attached GIF for details)

{ "key": "ctrl+k", "command": "workbench.action.terminal.sendSequence", "args": { "text": "cls \u000D" }, "when": "terminalFocus" }

1. The attached GIF shows, in order, the following:
   
   
   
   • "Terminal: Clear" command NOT working properly
   
   
   • "cls" and "clear terminal" commands working in integrated terminal
   
   
   • How to modify the keybindings.json file to make a keyboard shortcut
   
   
   • Verifying that keyboard shortcut works
   
   

Hope that this helps!

EDIT - Changed the code snippet
Using "CTRL+k" as shortcut key and not adding a "when": "terminalFocus" value in keybindings.json property somehow stops all other shortcuts that start with "CTRL+K" from running properly e.g. the default theme selection shortcut key (CTRL+K, CTRL+T)

So, either use a different shortcut key e.g. (CTRL+K, CTRL+K) for clearing the terminal - you can exclude "when": "terminalFocus" from the code snippet above and this shortcut will work even when you are not directly focused in the Terminal

Or else, include the "when": "terminalFocus" in the keybindings.json file (as is in the code snippet above) and the "CTRL+K" shortcut will run only when Terminal is in focus

[Pomax]

On Windows 10.0.18363.778 running cls in the terminal in VS Code 1.44 does not do as described in the above comment. Instead, it does the same thing as originally reported: it seemingly clears the terminal, then running _any command_ will show (part of) the previous console output.

[albertoarcagni]

I confirm. I noticed the same problem working with R and the extension vscode-R.
Initially, I reported the problem to the extension developers.
Here you can find the details with screenshots https://github.com/Ikuyadeu/vscode-R/issues/307#issuecomment-623534315
Once I verified the same problems with Python and the extension developed by Microsoft I can confirm it is a vscode issue.
I used a workaround too (a shortcut that runs an R command) but I prefer if the problem is solved.

[manwithsteelnerves]

At-least clear command is working for me. Command+K stopped from long time but I see something being expected post pressing Command + K. Please check the screenshot.

[Tyriar]

@manwithsteelnerves https://code.visualstudio.com/docs/editor/integrated-terminal#_why-is-cmdkctrlk-not-clearing-the-terminal

[manwithsteelnerves]

@Tyriar Thanks a lot it worked! Any reason it suddenly stopped? Can it be due to external extensions?

[Tyriar]

@manwithsteelnerves that happened when any extension adds a cmd+k chord keybinding. Actually that might have been fixed after the terminal.integrated.allowChords setting was added (true by default) 🤔, anyway that's not related to this particular issue.

[CullenW99]

I would like to join this conversation by saying that the use of '\033c' is also buggy. This is similar to issue #94231, which was deemed a duplicate of this one. When printing '\033c' to clear the terminal 3 (non blank) lines will correctly print in the terminal before it skips enough lines so that any new content can't be seen when scrolled to the top of the terminal. if the 3rd line is the end of input() the cursor will skip the same number of lines but be offset to match the end of the correct line. In addition, if you go back 2 entries the line you should be on is reprinted in the displaced area. The program ending will fix the spacing unless a path prompt is printed as/before the 4th line, where the next thing printed (or the 4th line if you were already on it) will skip lines. if you just click enter the path will back-fill the skipped lines, else it prints after your current line. If you cycle to your previous 2 entries before entering anything into the path prompt is will also duplicate at the bottom despite your cursor not being there, leaving your 1st previous entry on the line you were just on.

[Pratik-Hub]

If you are on linux then in .bashrc at last add a line 'alias clear='/bin/clear/' and save and at last you can retry

[mrwensveen]

I'm sorry to bump the issue again, but I couldn't find the bit that I wanted to add to the conversation. After clearing the terminal, when you switch to another terminal and back, the contents are there again. Running cls isn't an option for me because I'm looking at the output of several running processes.

My guess is that the cause is the same and that fixing the upstream bug will fix this too (or allowing this to be fixed). Could be useful as a test scenario though.

[mrkarthi]

My workaround for this. The history is still available when scrolled above.

{ "key": "alt+n", "command": "workbench.action.terminal.sendSequence", "args": { "text": "clear\u000D" } }