Strange characters appeared when entering Tmux

[hexh250786313]

Environment

Windows build number: Microsoft Windows [ver 10.0.19041.508]
Your Distribution version: Ubuntu 20.04
Whether the issue is on WSL 2 and/or WSL 1: WSL 2
Tmux ver: tmux next-3.3

Steps to reproduce

1. On WSL 2
2. Create a new session on tmux. I execute: tmux new -s test, then enter the session.
3. Or attach an old session: tmux attach -t test

Expected behavior

no strange characters

Actual behavior

There are some strange characters appeared before the cursor. They are 0;10;1c. Like this:

But it didn't always happen. This is a chance event.

[hexh250786313]

And it happened in both my desktop and laptop.

[hexh250786313]

And it didn't happened in WSL 1. But my WSL 1 is Ubuntu 18.04. I'm not sure this is related to the Linux version or the WSL version.

[hexh250786313]

Ok, I finally resolved it. It happened when tmux run on Ubuntu 20.04. When your .tmux.conf has the line set -sg escape-time 0, it happens.

On Ubuntu 18.04, I add this line because there is a delay when I press Esc key. But if I add the line set -sg escape-time 0 on 20.04, The strange characters appear. I think it is because of the 0s. Finally I change it to 50ms (500ms default).

So I just need to change the line to set -sg escape-time 50 on 20.04 and issue resolved.

[kcking]

Ok, I finally resolved it. It happened when tmux run on Ubuntu 20.04. When your .tmux.conf has the line set -sg escape-time 0, it happens.

On Ubuntu 18.04, I add this line because there is a delay when I press Esc key. But if I add the line set -sg escape-time 0 on 20.04, The strange characters appear. I think it is because of the 0s. Finally I change it to 50ms (500ms default).

So I just need to change the line to set -sg escape-time 50 on 20.04 and issue resolved.

Thank you for reporting your solution! This fixed my issue as well, I was also seeing 0;10;1c on tmux start (using wezterm and tmux on wsl2 debian).

[kchen0x]

It helps!

[roachsinai]

Seems it works only for the first time start a Session, if you exit current session and run tmux again, prints chars again.

Originally posted by @roachsinai in tmux-plugins/tmux-sensible#61 (comment)

[trallnag]

For me only thing that fixed the characters appearing was placing set -g escape-time 50 right at the beginning of my tmux.conf before using run-shell to source a shell script that contains the bulk of my configuration.

tmux-plugins/tmux-sensible#61 (comment)

[quique0194]

It seems like "tmux-sensible" plugins sets escape-time=0

>> grep escape-time -R .tmux/plugins
.tmux/plugins/tmux-sensible/README.md:set -s escape-time 0
.tmux/plugins/tmux-sensible/sensible.tmux:      if server_option_value_not_changed "escape-time" "500"; then
.tmux/plugins/tmux-sensible/sensible.tmux:              tmux set-option -s escape-time 0

[Blosberg]

Apparently the option in "sensible" is to avoid this issue, and the escape-time parameter will

'Set the time in milliseconds for which tmux waits after an escape is input to determine if it is part of a function or meta key sequences

Considering that, I think it would be advisable to set it as low as possible. I had the same problem as OP (with the exact same characters: 0;10;1c) when there was nothing in my .tmux.conf about escape time (because the value was being set by the "sensible" plugin to zero). When I explicitly set the value in .tmux.conf

set -sg escape-time 50

The weird character problem went away. Then when I set

set -sg escape-time 0

The problem came back. So that's what's causing it, but I don't want to have a lag when leaving insert mode, so I set the following:

set -sg escape-time 1 (which will allow 1 millisecond to escape insert mode --imperceptible to any human user, but enough to avoid these characters)

[smprather]

Note: I never had this problem with KiTTY. I am only seeing it now that I am trying to switch to Alacritty. Due to flakiness of the network I work on, I get a good number of disconnect/reconnects. Each reconnect to tmux generates this string. So I see it constantly. And it is not just "terminal noise". It is registering as real keystrokes to bash. This is what I see after a weekend of not working. (I hit Enter to verify that the chars were recognized by bash)

$ 0;10;1c0;10;1c0;10;1c0;10;1c0;10;1c0;10;1c0;10;1c0;10;1c0;10;1c0;10;1c0;10;1c0;10;1c0;10;1c0;10;1c0;10;1c0;10;1c0;10;1c0;10;1c0;10;1c0;10;1c0;10;1c0;10;1c0;10;1c0;10;1c                                                                                                                                                      bash: 10: command not found
bash: 1c0: command not found
bash: 10: command not found
bash: 1c0: command not found
bash: 10: command not found
bash: 1c0: command not found

[Dan1jel]

Also started to see this issue... dont know why but when i start a tmux new -s Big_letter_at_start it usually showd thouse wierd symols, but when i had all lowered case i didnt see it (set -s escape-time 1).

when i removed the line set -s escape-time 1 with # it all seams to work as intended...

[chrismferguson]

for anyone having it not work, place the set -s escape-time 1 line after the tmux sensible line.

[stewartli]

it happens to me after upgraded Ubuntu (V22). nothing above works for me.

[arecarn]

A related question similar to this was answered here: https://serverfault.com/a/1130091/481120.

Here's the relevant part of the answer:

It's the terminal's response to an ESC [ c "Request terminal attributes" that was issued by the remote program.

(\033[c "Request terminal attributes" is one of several information requests that tmux outputs to the terminal, expecting to receive similar responses as input coming from the terminal (normally they would be invisibly consumed by tmux, just like special-key sequences are).

[baydakovss]

set -s escape-time 1
In my case the issue disappeared when I put "tmux-sensible" and the workaround with "escape-time" just before initializing the plugins by plugin manager

set -g @plugin 'tmux-plugins/tmux-sensible'
# Workaround. Prevent appearing 0;10;1c when tmux start
set -sg escape-time 1
#
# Initialize TMUX plugin manager (keep this line at the very bottom of tmux.conf)
run '~/.tmux/plugins/tpm/tpm'

[ariusxi]

Ok, I finally resolved it. It happened when tmux run on Ubuntu 20.04. When your .tmux.conf has the line set -sg escape-time 0, it happens.

On Ubuntu 18.04, I add this line because there is a delay when I press Esc key. But if I add the line set -sg escape-time 0 on 20.04, The strange characters appear. I think it is because of the 0s. Finally I change it to 50ms (500ms default).

So I just need to change the line to set -sg escape-time 50 on 20.04 and issue resolved.

Thanks man, it works for me!

[khayo]

I know this is absurd and that this solution will give a loading error, but it was the only thing that made the strange characters not appear

set -sg escape-time -1

I'm using manjaro i3 with urxvt terminal

[baleti]

set -sg escape-time 50 did nothing, issue still persists on every terminal except for wt.exe (windows terminal)

UPDATE: sorry, set -sg escape-time 1, works, it was just getting overwritten by another line setting it to 0 again later down my .tmux.conf
I also noticed strange "locking" behaviour in emacs in terminal when this is set to 0, not quite sure what's going on under the hood

[Dan1jel]

set -sg escape-time 50 did nothing, issue still persists on every terminal except for wt.exe (windows terminal)

I have set -s escape-time 0 in my .tmux.conf file. Haven't got this issue for a long time now. Also need to mention that I have this config on my Ubuntu laptop also.