I am using KDE Neon as my daily driver on my laptop. Recently due to KDE Neon update 6.0, there have been many bugs, but one as annoying as the one I faced the other day.

After system update, my bash stopped working completely. Granted I use zsh as my shell, bash is required by many programs on Linux. But everytime, I opened any such program, say pyenv, it just wouldn't work and give following error

/usr/bin/env: ‘bash’: No such file or directory linux

I looked into /usr/bin and couldn't find bash there. I couldn't install bash using dpkg or apt. This was pretty perplexing for me. Here is how I resolved the error with bash.

First of all, I edited the file /var/lib/dpkg/info/bash.prerm and changed first line to #! /bin/sh from #! /bin/bash

#! /bin/sh
set -e  

case "$1" in  
   upgrade)  
       update-alternatives --remove builtins.7.gz \  
           /usr/share/man/man7/bash-builtins.7.gz  
       ;;  

   remove|deconfigure)  
       ;;  

   failed-upgrade)  
       ;;  
   *)  
       echo "prerm called with unknown argument \`$1'" >&2  
       exit 1  
       ;;  
esac

Next I looked into /var/cache/apt/archives/ and found the file bash_5.1-6ubuntu1.1_amd64.deb. If you cannot find this file, you can download from here
Next I ran the command

sudo dpkg --force-remove-reinstreq -i /var/cache/apt/archives/bash_5.1-6ubuntu1.1_amd64.deb

This helped me restore the bash and helped me run programs again.