When I modify a single file and then run git status I get:
# On branch master
# Changes not staged for commit:
# (use "git add <file>..." to update what will be committed)
# (use "git checkout -- <file>..." to discard changes in working directory)
#
# modified: app/models/category.rb
#
no changes added to commit (use "git add" and/or "git commit -a")
Why there is the line (use "git add <file>..." to update what will be committed) ??
There isn’t file to add in my repo.
git-addis also used to add changes from the working copy into the index. The index is used to build a commit before it is actually committed.See e.g. http://schacon.github.com/git/user-manual.html#how-to-make-a-commit