This is to avoid accidentally cloning a repo as read-only when GitHub defaults to HTTPS links, and then having to edit the gitconfig later to get an SSH URL you can push to. Add these 2 lines to your global .gitconfig file in your home folder to override all github.com URLs from HTTPS to SSH:
[url "ssh://firstname.lastname@example.org/"] insteadOf = https://github.com/
Note, this is not for all git remotes, only GitHub. I have a similar setting for the GitHub Enterprise instance we use at work. Generally though, for most remote servers I’m fine with whatever it gives me, which is usually HTTPS.
The difference becomes important if I ever want to contribute (i.e. push) to the cloned repo, as is mostly the case when cloning my own repos or work code. Continue reading