Question

I want to add a shortcut like I type :open_my_document, it become :e /var/book/document.txt.
how to?

Answer 1

If you want to create a custom command, use :command:

:command Open_my_document e /var/book/document.txt

Then you can use:

:Open_my_document

Normally you can just type :Ope and then hit tab and vim will complete the full command name.

Note that your command needs to start with a capital letter because only built-in vim commands can start with lower-case letters.