git commit -a -m gives error for file not being tracked

Question

I am learning to work with git and I'm playing around with branching. I created a file "test.rb" and committed a version on a 'testing' branch.

Being on 'master' I use git commit -a -m 'msg' and get this message:

On branch master
Untracked files:
  (use "git add <file>..." to include in what will be committed)
        test.rb

nothing added to commit but untracked files present (use "git add" to track)

I cannot understand why, since the '-a' flag should add everything to staging and commit it.

What am I missing? Thanks !

Answer 1

Since the test.rb file is not yet tracked by git, you need to add it first using git add

git add test.rb
git commit -m "msg"

After that, if you add changes to this file, you can use the -a option to commit your changes

git commit -am "msg"

This is also highlighted by the description for the -a flag in git's help:

$ git commit --help
-a, --all
           Tell the command to automatically stage files that have been
           modified and deleted, but new files you have not told Git about
           are not affected.