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

If you just want a "quick and dirty" way to stash changes on the current branch, you can use the following alias:

git config --global alias.temp '!git add -A && git commit -m "Temp"'  

After running that command, you can just type git temp to have git automatically commit all your changes to the current branch as a commit named "Temp". Then, you can use git reset HEAD~ later to "uncommit" the changes so you can continue working on them, or git commit --amend to add more changes to the commit and/or give it a proper name.