CODE EXAMPLE FOR SHELL

error: src refspec master does not match any

Try git show-ref to see what refs you have. Is there a refs/heads/master?
Due to the recent "Replacing master with main in GitHub" action, 
you may notice that there is a refs/heads/main. 
As a result, the following command may change from git push origin HEAD:master 
to git push origin HEAD:main

So try `git push origin main`