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`clear`/`ctrl-l` don't work #1235

dbarella opened this Issue Jan 15, 2018 · 4 comments


2 participants

dbarella commented Jan 15, 2018

Howdy y'all,

I'm having a heck of a time with this issue -- I've been on a documentation bender for the past hour at least, and at this point I think I have to give up and report a bug (or be proven silly, either way works).

The Issue


Pretty plain and simple, I can't get clear/ctrl-l to actually clear the screen -- the cursor will reset back to the top of the screen, but it seems that no redraw happens. I can trigger a redraw (completing the actual clear) by doing something like opening a split -- but on its own, nada.

I've attempted tput reset; clear; commandline -f repaint to no avail -- text remains on the screen.


$ tmux -Ltest kill-server
no server running on /tmp/tmux-1000/test
$ tmux -vv -Ltest -f/dev/null new

# Now in tmux
$ echo $TERM
$ clear

# Cursor resets to top of screen, but only clears the first line -- everything else persists.


I believe that this is some arcane issue, possibly having to do with an interaction between tmux and ncurses. My reasoning:

  • clear/ctrl-l both work fine outside of tmux
  • The problem persists across several shells within tmux -- most notably bash, as well as fish

To this end, I tried to figure out if any ncurses5 shared objects were being invoked where ncurses6 ones should have been, but unfortunately I'm just a lowly backend systems programmer, so I wasn't really sure how to figure that out...

System Info

  • I'm running a Kubuntu (16.04.3 LTS) on a Lenovo Thinkpad X1 Carbon (5th Gen).
  • I'm running bash and fish-shell. This problem occurs across both!
  • All packages are up-to-date by apt -- I ran sudo apt update && sudo apt upgrade about an hour ago and still repro'd

Here's some data:

# Note: I'm using fish-shell to get this info

$ uname -sp; tmux -V; echo $TERM
Linux x86_64
tmux 2.6

$ cat /etc/lsb-release 

$ bash --version
GNU bash, version 4.3.48(1)-release (x86_64-pc-linux-gnu)                                                              
Copyright (C) 2013 Free Software Foundation, Inc.                                                                      
License GPLv3+: GNU GPL version 3 or later <>                                          
This is free software; you are free to change and redistribute it.                                                     
There is NO WARRANTY, to the extent permitted by law.      
$ fish --version
fish, version 2.7.1 

$ tmux
Welcome to fish, the friendly interactive shell
Type help for instructions on how to use fish
$ echo $TERM



Other Useful Reading

I found this issue enlightening, but couldn't find any pieces that I could easily apply to this problem.


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nicm commented Jan 15, 2018


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dbarella commented Jan 15, 2018

Yep! Is this some escape sequence trickery?


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nicm commented Jan 15, 2018

This is a bug in Konsole,, try upgrading Konsole or:

set -as terminal-overrides ',*:indn@'


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dbarella commented Jan 15, 2018

The terminal override works; I'm going to use that until a Konsole upgrade comes through the stable pipeline. Thanks for the tip!

@dbarella dbarella closed this Jan 15, 2018

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