GitHub recently improved security, so you may get the error below like I did when I tried to install oh-my-zsh on a new Mac.
Anton.Perez@amp ~ % sh -c "$(curl -fsSL https://raw.github.com/ohmyzsh/ohmyzsh/master/tools/install.sh)"
Cloning Oh My Zsh...
fatal: remote error:
The unauthenticated git protocol on port 9418 is no longer supported.
Please see https://github.blog/2021-09-01-improving-git-protocol-security-github/ for more information.
/Users/Anton.Perez
Error: git clone of oh-my-zsh repo failed
You can test if it’s because you need to add an SSH key by running:
ssh -vvv git@github.com
You’ll get an error like so if so:
...
debug2: we did not send a packet, disable method
debug1: No more authentication methods to try.
git@github.com: Permission denied (publickey).
If so, just generate a new key and add it to your GitHub account (see this. That’s it!