I want to change entering vi mode key-set to prefix + v or prefix + C-v.
By default tmux uses prefix + [ to enter vi mode. I tried to send-prefix + send-keys with bind but it didn't work.
I don't know if tmux allows such operations, but I think prefix + [ is not very useful.
If you would like VI mode to be permanently enabled, add this line to your ~/.tmux.conf:
set-window-option -g mode-keys vi
Restart tmux or run Ctrl+B+: then source-file ~/.tmux.conf inside of tmux.
Putting this in your .tmux.conf will do it:
bind 'v' copy-mode
You can find what keys are bound to what commands with:
tmux list-keys