repository - Untrack files from git in worktree -

i have 3 machine, local -> server -> server b
, programming on local, use git push local code server a,
on server set hook push code server b,
both on server , server b have configure this

$ git config core.worktree /home/www $ git config core.bare false $ git config receive.denycurrentbranch ignore 

and have hook git checkout -f

how can change files on server b , not track it?

i try git update-index --assume-unchanged path/to/file
alway notice fatal: unable write new index file

i'm sure user have permission in folder(can write, read , execute)
try git update-index --skip-worktree path/to/file doesn't work

you should have .gitignore file in repository. can include files should not tracked .gitignore, read more here.