How to Set Default Editor to Vi in KSH

You might find out your shell does not respond to your esc + k which can reuse the historical commands in KSH just like ↑ in bash. This is because the default EDITOR in your shell has not been set.

There're several ways to solve this:

1. For session-scope only:
$ set -o vi

2. For single user:
$ vi ~/.profile
...
EDITOR=vi; export EDITOR

3. For all users:
$ vi /etc/profile
...
EDITOR=vi; export EDITOR