On Thu, 3 Feb 2022 19:02:14 +0900 Koichi Murase wrote: > I'm not sure what this exactly is related to, but I guess pcon is > closely related.
No, this is not related to pseudo console. > Cygwin version: > > I can reproduce it in Cygwin 3.2.0 and the latest 3.3.4 for both > 64-bit and 32-bit versions. I usually set CYGWIN=disable_pcon, but > this reproduces for both cases with and without disable_pcon. > > I think I observed this behavior even earlier but don't exactly > remember in which Cygwin version I first noticed this broken behavior. > At least, this behavior has existed for a very long time. I have been > thinking that there are a few people using the Cygwin console > directly, but I recently noticed that it matters when I connect to > Cygwin from Windows Terminal. This puts very hard limitations on > implementing a line editor where the line editor does not know the > absolute vertical position in the terminal screen so cannot predict > the consequences of using DL/IL. > > Repeat-by: > > 1. First open a Cygwin console (not to be confused with Mintty) by > double-clicking bash.exe in C:\cygwin64\bin or by executing "cygstart > bash". > 2a. run the following command at the last line of the terminal: > > $ printf '\e[5M' > > 2b. run the following command at the last line of the terminal > > $ printf '\e[5L' > > The control sequence \e[<Pn>M (CSI <Pn> M) is the ANSI escape sequence > DL (DELETE LINE), which is supposed to delete the current line and the > following <Pn>-1 lines and scrolls up the subsequence lines. This > control function functions correctly when it is not at the last line > in the Cygwin console. However, if the current cursor position is > located at the last line, DL(<Pn>) of the Cygwin console wrongly > scrolls up the entire screen by <Pn> lines (instead of the subsequent > lines after the delete lines). > > Likely, \e[<Pn>L is the ANSI escape sequence IL (INSERT LINE), which > is supposed to insert <Pn> new lines at the current line and to scroll > down the subsequent lines. However, when the cursor is at the last > line, IL of the Cygwin console again scrolls down the entire screen. > > This behavior is also reproduced in Windows Terminal with a profile of > Cygwin executing bash.exe --login -i. This doesn't happen when we use > Mintty or other terminal emulators relying on the genuine Cygwin PTY. > > Fix: > > Any other terminals do not behave in this unintuitive way. When the > cursor is located at the last line, DL/IL should not scroll any lines > but should just clear only the last line. Thanks for the report. I can reproduce the problem. I will submit a patch for this issue shortly. -- Takashi Yano <takashi.y...@nifty.ne.jp> -- Problem reports: https://cygwin.com/problems.html FAQ: https://cygwin.com/faq/ Documentation: https://cygwin.com/docs.html Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple
