The git status command will show if a file is ready to be committed. In this example, foo.txt is not ready to be committed. This usually occurs when no changes have been made to the file.
git status /path/to/foo.txt . . . nothing to commit (working directory clean)
When a new file is added to git, the following will be displayed.
git status /path/to/foo.txt . . . Changes to be committed: . . . new file: foo.txt
When a change is made to a staged or commited file, the file will be listed as modified in the git status command.
git status /path/to/foo.txt . . . modified: foo.txt