Question

How can I stage and commit all files, including newly added files, using a single command?

Answer 1

Does

git add -A && git commit -m "Your Message"

count as a "single command"?

Edit based on @thefinnomenon’s answer below

To have it as a git alias, use:

git config --global alias.coa "!git add -A && git commit -m"

and commit all files, including new files, with a message with:

git coa "A bunch of horrible changes"

Explanation

From git add documentation:

-A, –all, –no-ignore-removal

Update the index not only where the working tree has a file matching but also where the index already has an
entry. This adds, modifies, and removes index entries to match the
working tree.

If no <pathspec> is given when -A option is used, all files in the
entire working tree are updated (old versions of Git used to limit the
update to the current directory and its subdirectories).