^@ Constantly printed in Linux console

hako · 2016-07-22 06:24:22

I just installed Arch Linux on my laptop today, and while most things seem to be working, the two characters '^@' are almost constantly printed when using the Linux console. They seem to print in pairs every second or so when a program is running and printing to the console. However, they don't show when no programs are running and just the prompt is showing.

Just as an example, this is what happens when I run the following bashscript:

> for i in $(seq 1 10); do
>     echo $i
>     sleep 1
> done
1
^@^@2
^@^@3
^@4
^@^@5
^@^@6
^@^@7
^@8
^@^@9
^@^@10

I have experienced this with my own bashscripts (like above), vim, gdisk and cgdisk, and pacman, and it probably occurs on most other programs too. Another interesting thing is that with vim and cgdisk, rows of the screen would flash white when the '^@'s were printed.

My Laptop is a Lenovo Thinkpad P50 dual booting Windows 10 and Arch Linux. I followed the beginner's guide pretty closely and I have succesfully installed Arch Linux and Debian once on a mac before, but this is my first time trying to do it on a windows computer. If there's any more information you need, please ask! Unfortunately, I logged out of Linux and now it won't let me log back in because the '^@'s prevent me from entering the correct password! (Oddly enough, I was able to log in the first time though...)

Anyways, I would love to be able to fix this and be able to use my arch installation properly. Any ideas?

R00KIE · 2016-07-22 14:01:57

That seems to point to something periodically sending key presses. Check if it also happens on windows and if rebooting from windows to Arch makes any difference.

Also make sure you update the bios/firmware because it might contain a fix for that.

hako · 2016-07-27 04:06:13

Sorry for the late response, but I've finally determined that the problem is caused by plugging an external display into my computer's HDMI port. Any ideas why this would cause the characters to be printed? FWIW, I have not been able to get my HDMI to work yet and it is not listed when I run xrandr, but that's probably just because I haven't looked into it that much. Also, my computer has both an integrated Intel HD graphics 530 and a dedicated Nvidia Quadro M1000M.

R00KIE · 2016-07-27 09:37:29

hako wrote:

Sorry for the late response, but I've finally determined that the problem is caused by plugging an external display into my computer's HDMI port. Any ideas why this would cause the characters to be printed?

If that external display is a TV or similar I can only think about CEC commands sent from the TV. If it isn't I have no ideas.

Arch Linux

#1 2016-07-22 06:24:22

^@ Constantly printed in Linux console

#2 2016-07-22 14:01:57

Re: ^@ Constantly printed in Linux console

#3 2016-07-27 04:06:13

Re: ^@ Constantly printed in Linux console

#4 2016-07-27 09:37:29

Re: ^@ Constantly printed in Linux console

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