How to do a rebase with git gui?

Question

I know how to do a git rebase from the command line, but how do you do it with the official git-gui?

Answer 1

In git-gui:

1. Go to Tools -> Add and then enter a custom command i.e. git rebase master.
2. Select Add globally to have this option appear for all repositories. (It will write the configuration to your ~/.gitconfig for you, as @Ted-Percival mentioned in his answer).