Bash is insane and this should be illegal: bind -m vi-insert "\C-l":clear-screen. On Ubuntu, there’s no official package for oksh, only an outdated PPA.
This guides use doas instead of sudo.
$ doas apt install -y gcc make
$ git clone https://github.com/ibara/oksh
$ cd oksh
$ ./configure
$ doas make && doas make install
$ doas echo '/usr/local/bin/oksh' >> /etc/shells
$ chsh
Password:
Changing the login shell for $USER
Enter the new value, or press ENTER for the default
Login Shell [/usr/bin/bash]: /usr/local/bin/oksh
Start a new shell and be greeted with:
oksh: /etc/profile.d/Z99-cloud-locale-test.sh[100]: local: not found
oksh: /etc/profile.d/Z99-cloud-locale-test.sh[100]: local: not found
oksh: /etc/profile.d/Z99-cloudinit-warnings.sh[29]: local: not found
oksh: /etc/profile.d/Z99-cloudinit-warnings.sh[29]: local: not found
oksh: /etc/profile.d/Z99-cloudinit-warnings.sh[29]: local: not found
Let’s fix that quickly:
$ doas su
# mv /etc/profile /etc/profile.bak
# echo 'export ENV=$HOME/.kshrc' > profile
Set a couple sane defaults on your .kshrc:
set -o vi
PS1='\u@\h:\W\$ '