Bug 481294

Summary:	Sequence <ESC>[3J is implemented incorrectly (should erase whole screen AND clear the scrollback buffer)
Product:	[Applications] konsole	Reporter:	Mikko Rantalainen <mikko.rantalainen>
Component:	emulation	Assignee:	Konsole Bugs <konsole-bugs-null>
Status:	RESOLVED NOT A BUG
Severity:	normal	CC:	ninjalj
Priority:	NOR
Version First Reported In:	21.12.3
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Mikko Rantalainen 2024-02-13 15:43:08 UTC

SUMMARY

According to `man console_codes` the CSI sequence

> ESC [ 3 J: erase whole display including scroll-back buffer

but Konsole implements it as simply clearing the scrollback buffer without erasing the display.

STEPS TO REPRODUCE
1. Run something to have text on screen and scrollback buffer.
2. Execute following command

    printf "\033[3J"

OBSERVED RESULT

Terminal scrollback buffer is deleted but the text visible on the terminal is not touched.

EXPECTED RESULT

There should be no visible text and the scrollback buffer should be empty.

Tested with Ubuntu 22.04 LTS and Konsole version 21.12.3.

$ apt-cache policy konsole
konsole:
  Installed: 4:21.12.3-0ubuntu1
  Candidate: 4:21.12.3-0ubuntu1
  Version table:
 *** 4:21.12.3-0ubuntu1 500
        500 http://fi.archive.ubuntu.com/ubuntu jammy/universe amd64 Packages
        100 /var/lib/dpkg/status

Comment 1 ninjalj 2024-02-24 23:02:40 UTC

CSI 3 J comes from xterm, where it only clears the scrollback buffer. VTE (gnome-terminal, xfce-terminal, ...) behaves likewise. Putty also follows that behavior.

See https://invisible-island.net/xterm/ctlseqs/ctlseqs.html#h3-Functions-using-CSI-_-ordered-by-the-final-character_s_ :

CSI Ps J  Erase in Display (ED), VT100.
            Ps = 0  ⇒  Erase Below (default).
            Ps = 1  ⇒  Erase Above.
            Ps = 2  ⇒  Erase All.
            Ps = 3  ⇒  Erase Saved Lines, xterm.

So, CSI 2 J erases all the screen, but not the scrollback buffer, while CSI 3 J erases the scrollback buffer, but not the screen.