fatal: Unable to mark file .ruby-version

[Arup Rakshit <aruprakshit@rocketmail.com>]

Hi,

I am trying to ignore 2 files, but getting error -

[arup@sztukajedzenia (SJ002)]$ git status
# On branch SJ002
# Untracked files:
#   (use "git add <file>..." to include in what will be committed)
#
#       .ruby-gemset
#       .ruby-version
nothing added to commit but untracked files present (use "git add" to track)
[arup@sztukajedzenia (SJ002)]$ git update-index --assume-unchanged .ruby-gemset
fatal: Unable to mark file .ruby-gemset
[arup@sztukajedzenia (SJ002)]$ git update-index --assume-unchanged .ruby-version
fatal: Unable to mark file .ruby-version
[arup@sztukajedzenia (SJ002)]$

Why it is throwing error ? And how to achieve this without taking the help of the file `.gitignore` ?

-- 
================
Regards,
Arup Rakshit
================
Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it.

--Brian Kernighan