The commit command accepts multiple -m flags:
$ git commit -m "Commit title" -m "A new paragraph."
Each use adds a new paragraph to the commit message. A similar effect can be achieved using quotes:
$ git commit -m "Commit title > > A new paragraph."
If you belatedly decide that you should have used an editor after all you can pass the -e flag to open your editor with the partially-complete message intact:
$ git commit -m "Commit title" -m "Now I want an editor..." -e
Adding this snippet to your .gitconfig file creates a git alias command which lists all
registered aliases:
[alias]
alias = !git config --list | grep alias | sed s/^alias.//
Write a commit message, hit return, instantly notice the typo...
The fix is to run:
git commit --amend
This opens the last commit message in your editor, allowing you to rewrite it. I do this often
enough that I've added the following alias to my .gitconfig file:
[alias]
amend = commit --amend
This way I can run git amend instead.