Rename file but not from scratch

[omnigenous]

Sometime I get files with really long names but I just need to change small part of it (ex: remove underscores) and retyping entire name prone to typos.

Here is my setup:

map r push :rename<space>
cmd rename %[ -e $1 ] && printf "file exists" || mv $f $1

When I press r :rename appears at the bottom, can this be change to :rename FILE_NAME.EXT and/or :rename FILE_NAME (without ext).
I tried:

+ map r push :rename<space> $f

But that just adds literal $f.

[DusanLesan]

I don't know how to help with that, but I'm curious: what makes the built-in rename feature unsuitable for you?

[omnigenous]

Nothing, I don't remember why I implemented my own because I did go through entire wiki page in github but still did not know there built in rename.

https://github.com/gokcehan/lf/wiki/Tips#enhancing-the-rename-command